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TSUNAMI DATABASES FOR THE NATIONAL TSUNAMI EARLY WARNING CENTRE OF MALAYSIA : TOWARD THE IMPLEMENTATION PLAN OF REGIONAL TSUNAMI WATCH PROVIDERS (RTWP) Chai Mui Fatt, Asmadi bin Abdul Wahab, Norhadizah binti Mohd Khalid, Nasrul Hakim bin Hashim, Muhammad Nazri bin Noordin and Mohd Rosaidi bin Che Abas ABSTRACT The purpose of this study is to develop a tsunami database for the National Tsunami Early Warning Centre of Malaysia, towards the implementation plan of Regional Tsunami Watch Providers (RTWP). Firstly, we determined the tsunami source points along the most active subduction zones at an interval of 0.5 degree (~50 km) with 5 magnitudes (Mw 6.5, 7.0, 7.5, 8.0 and 8.5) and 4 depths (0, 20, 40 and 60 km). The coastal and forecast points are located along the coastal area at 1 and 50 m of bathymetric contour depth with random interval distance, respectively. In numerical simulations, TUNAMI-F1 (Tohoku University‟s Numerical Analysis Model for Investigation of Far-field tsunami, No. 1), TUNAMI-N2 (Tohoku University‟s Numerical Analysis Model for Investigation of Near-field tsunami, No. 2) and NAMI-DANCE version 4.7 are used to calculate the tsunami waveforms at the outpoint points. Green‟s Law calculations are then applied to the tsunami heights at forecast points to estimate the reliable tsunami heights for the coastal points. Tsunami arrival times at the coastal points are then calculated by inverse tsunami arrival time using the TTT (Tsunami Travel Times) software. The empirical equations of the Scaling Law are used to determine the fault parameters of earthquake which is controlled by moment magnitude. Tsunami databases are then constructed by using MySQL database which combined 3 major components at the Malaysian National Tsunami Early Warning System (MNTEWS). This precomputed tsunami database contains more than 30,000 earthquakes scenarios covering the most active subduction zones historically. Combinations of PHP scripting language and SQL command syntax are performed to retrieve the database output by simple, interpolation, extrapolation and maximum risk methods. The threat levels of warning, alert and watch are issued based on wave amplitude and arrival times of tsunamis at the coastal points. _________________________________________________________________________________ The author works for Malaysian Meteorological Department, Malaysia. TABLE OF CONTENTS ABSTRACT TABLE OF CONTENTS 1. INTRODUCTION 1.1 Seismicity and Tectonics of Malaysia 1.2 Felt Earthquakes 1.3 Local Origin Earthquakes 1.4 Recent Tsunamis 1.5 Tsunami Early Warning System in Malaysia 1.5.1 Overview of the Malaysian National Tsunami Early Warning System 1.5.2 Seismic Network 1.5.3 Tide Gauge Network 1.5.4 Deep Ocean Buoy Network 1.5.5 Coastal Camera Network 1.5.6 Tsunami Siren Warning Network 1.5.7 Disaster Alert System (DAS) 1.6 Review and Purpose 1.7 Scope of Study Area 1 2 3 4 5 6 6 7 8 9 10 11 12 12 12 2. DATA 2.1 Bathymetry Data 13 13 3. THEORY 3.1 Causes of Tsunami 3.2 Ocean Bottom and Sea Surface Displacements 3.3 Propagation of Near-field Tsunamis 3.3.1 Governing Equation in Cartesian Coordinate System 3.3.2 Bottom Friction Term 3.4 Propagation of Far-field Tsunamis 3.4.1 Governing Equation in Spherical Coordinates System 3.5 Ocean Bottom Deformation 3.6 Scaling Law 3.7 Green‟s Law 3.8 Numerical Model 3.8.1 Staggered leap-frog Scheme 3.8.2 Numerical Stability 14 14 14 14 15 15 16 17 17 18 18 19 19 21 4. METHODOLOGY 4.1 Tsunamigenic Earthquake Locations 4.2 Magnitude and Depth 4.3 Source Points 21 21 23 24 4.4 Forecast and Coastal Points 4.4.1 Green’s Law 4.5 Initial Condition 4.5.1 Depth of Top Left Corner 4.5.2 Location of Top Left Corner 4.5.3 Ocean Bottom Deformation 4.6 Inverse Tsunami Travel Times 4.7 Tsunami Numerical Simulation Models 4.7.1 Numerical Simulation by TUNAMI-F1 4.7.2 Numerical Simulation by TUNAMI-N2 4.7.3 Numerical Simulation by NAMI-DANCE 4.7.4 Validation Model by TUNAMI-F1 in Spherical Coordinates System 4.7.5 Validation Model by NAMI-DANCE in Spherical Coordinates System 4.7.6 Validation Model by TUNAMI-N2 in Cartesian Coordinate System 4.7.7 Validation Model by NAMI-DANCE in Cartesian Coordinate System 4.8 Tsunami Database 4.8.1 Construction of Tsunami Database 4.8.2 SQL Commands 4.9 Retrieving from Tsunami Database 4.9.1 Simple Method 4.9.2 Interpolation Method 4.9.3 Extrapolation Method 4.9.4 Maximum Risk Method 4.10 Earthquake and Tsunami Bulletins 4.10.1 Warning Category 4.10.2 Design of Earthquake Bulletin No. 1 4.10.3 Design of Tsunami Bulletin No. 2 4.10.4 Design of Tsunami Bulletin No. 3 (Upgrade or Downgrade) 4.10.5 Design of Tsunami Bulletin No. 4 (Cancellation of Warning) 5. RESULTS AND DISCUSSION 5.1 Tsunami Heights 5.1.1 Different Magnitude at Fixed Depth 5.1.2 Different Depths at Fixed Magnitude 5.1.3 Different Source Points 5.2 Tsunami Travel Times 5.2.1 Different Magnitude at Fixed Depth 5.2.2 Different Depths at Fixed Magnitude 5.2.3 Different Source Points 5.2.4 Comparison of Tsunami Arrival Times between TTT and Simulation Result 5.3 Application of Green‟s Law 5.4 Validation Models 5.4.1 TUNAMI-F1 in Spherical Coordinates System 5.4.2 NAMI-DANCE in Spherical Coordinates System 25 26 27 27 28 29 31 34 34 34 35 35 37 38 39 40 41 42 43 43 44 47 48 49 50 51 52 54 55 56 56 56 57 58 59 59 60 61 62 63 64 64 66 5.4.3 TUNAMI-N2 in Cartesian Coordinate System 5.4.4 NAMI-DANCE in Cartesian Coordinate System 5.4.5 Comparison Waveforms at the Outpoints Points 5.5 Tsunami Database 5.5.1 Simple Method 5.5.2 Interpolation Method 5.5.3 Extrapolation Method 5.5.4 Maximum Risk Method 5.6 Comparison of Database Output 5.6.1 Tsunami Heights 5.6.2 Tsunami Arrival Times 5.7 Application of Searching Methods 5.8 Web Application for Tsunami Database 5.9 Scenario Case 5.9.1 Earthquake Bulletin No. 1 5.9.2 Tsunami Bulletin No. 2 5.9.3 Tsunami Bulletin No. 3 5.9.4 Tsunami Bulletin No. 4 67 69 70 71 72 72 72 72 73 74 75 76 77 78 78 79 83 84 6. CONCLUSIONS AND RECOMMENDATIONS 85 FUTURE PLAN 86 ACKNOWLEDGEMENT 86 APPENDICES 87 REFERENCES 108 1. INTRODUCTION The Indo-Australia Plate is moving northward against the Eurasian Plate at the rate of 37 to 57 mm per year. Historically, no large earthquake with a moment magnitude, Mw greater than 8.0 had occurred along the boundary of these two plates for over a century. Seismically, this region was relatively quiescent. However, on 26 December 2004, the Sumatran mega-thrust earthquake occurred in the west coast of Northern Sumatra, Indonesia with a moment magnitude, Mw 9.3 and triggered a massive tsunami which devastated throughout several countries bordering the Indian Ocean and caused significant damages to Malaysia. The great Sumatran earthquake produced 1.1 x 1017 Nm of total energy at the depth of 20-30 km with maximum length of 1200 km along the interface between the Indonesia and Burmese plates and 20 m displacement of the fault plane (Murty, 2007). The devastating tsunami waves struck along the northwest coastal areas in Peninsular Malaysia particularly in the coastal areas of Penang, Kedah, Perlis and to a lesser extent Perak and Selangor. The tsunami claimed 68 lives, 6 missing and 300 victims injured (The Star Newspaper, 2005) and the estimated cost of destroyed properties about RM100 millions (e.g. Tajul, 2005). In response to this event, the Malaysian government has decided to set up the Malaysian National Tsunami Early Warning System in 2005 by deploying deep ocean tsunami buoys in strategic locations, coastal surveillance monitoring cameras, warning sirens, tide gauges and seismic stations. Apart from that, the government has to increase the public awareness and disaster preparedness especially in tsunami hazard at the community level. In November 2007, the Malaysian Meteorological Department (MMD) had conducted the first public awareness disasters campaign on earthquake and tsunami held in Sabah. This campaign also has been extended into high risks areas in Sarawak and Peninsular Malaysia in 2008 and 2009. Page 1 of 110 1.1 Seismicity and Tectonics of Malaysia Malaysia is located close to the most seismically active plate boundaries between the IndoAustralia Plate and Eurasian Plate in the west and between Philippine Sea Plate and Eurasian Plate in the east (Figure 1). Generally, Malaysia is considered as a country with relatively low seismicity except for the state of Sabah. Therefore, Malaysia is facing a certain degree of earthquake risks from both distant and local earthquakes, particularly in Sabah. Major earthquakes with long period surface waves originating from active seismic areas along the subduction zones in west coast of Sumatra, Sulawesi and Philippines have been felt especially in the west coast of Peninsular Malaysia and Sabah. Thus, empirical evidence suggests that Malaysia is not totally free from seismic risks. I n d o A u s t r a l i a E u r a s i a n p l a t e Figure 1. Seismicity and tectonics profile in the area of reporting from 1979 to 2008. The colors and circles areprepresenting the categories of the hypocenter depth and magnitude, respectively. l a t e Page 2 of 110 1.2 Felt Earthquakes A felt earthquake is referring to the tremors felt in Malaysia due to the earthquake activities in the active seismic areas mainly along the Sumatra subduction zone, Sumatra fault line and earthquakes of local origin. In the past 30 years, the Malaysian Meteorological Department recorded 98 felt earthquakes in total since 1979 in the area of reporting (Figure 2). Peninsular Malaysia had experienced tremors originating from the Sumatra earthquake belt with maximum intensity up to VII on the Modified Mercalli Intensity (MMI) scale. While Sabah and Sarawak had experienced earthquakes of local origin, appeared to be related with several active faults, and the maximum MMI scale was VII and VI, respectively (MMD, 2009a). Figure 2. Felt earthquakes recorded by local seismological stations from 1979 to 2008. Page 3 of 110 1.3 Local Origin Earthquakes Malaysia had also experienced earthquakes of local origin (Figure 3). These local earthquakes are associated with active fault that exists in Peninsular Malaysia, Sabah and Sarawak. Several possible active faults have been delineated and local earthquakes in Peninsular Malaysia are appearing to be isolated and infrequent. Earthquakes of local origin which had occurred in Terengganu in 1995 were resulted from the impounding of the Kenyir Dam and not due to tectonism. Between 30 November 2007 and 25 May 2008, a total of 22 weak earthquakes with magnitudes ranging from 1.8 to 3.5 had occurred in Bukit Tinggi, Pahang. The 1976 Lahad Datu earthquake with a magnitude of 5.8 on the Richter scale had caused some houses and buildings to develop cracks in the walls. A four-storey police complex nearing completion was severely damaged. Several roads in the district are reported to have cracked too, causing damages. Similarly, the 1991 Ranau earthquake of a magnitude of 5.2 on the Richter scale caused extensive damages to a four-storey teacher‟s quarters, and was certified unfit for occupation. The earthquake with a magnitude of 4.8 occurred on 2 May 2004 near Miri, Sarawak likewise caused some damages to the non-reinforced concrete buildings and developed cracks on the ground. In 2009, MMD had recorded 16 weak earthquakes. The earthquake distributions were fourteen (14) in Peninsular Malaysia and two (2) in Sabah. Figure 3. Local origin earthquakes recorded from year 1979 to 2008 in Malaysia. Page 4 of 110 1.4 Recent Tsunamis In the last half decade, many recent earthquakes along the subduction zones had generated tsunami events (Table 1 and Figure 4). The Indian Ocean Tsunami on 26 December 2004 was the most significant recent tsunami which devastated throughout several countries bordering the Indian Ocean. The final death toll amounted to 229,867 people, the largest for any tsunami event and one of the greatest for any natural disaster (United Nations, 2006). Table 1. Information of the recent earthquake events from 2004-2009 (USGS) Date Dec 2004 Jul 2006 Jan 2007 Apr 2007 Sep 2007 Nov 2008 Jan 2009 Aug 2009 Sep 2009 Earthquake Sumatra-Andaman West Java Molucca Sea Solomon Islands Bengkulu Sulawesi Irian Jaya Andaman Islands Southern Sumatra Magnitude (Mw) 9.1 7.8 7.5 8.0 8.4 7.3 7.6 7.6 7.6 Longitude 95.8540E 107.3200E 132.7830E 156.9570E 101.3820E 122.1000E 126.3950E 92.9230E 99.8560E Latitude 3.3160N 9.2220S 0.15100S 8.4530S 4.5170S 1.2900N 1.2220N 14.0130N 0.7250S Figure 4. Epicenters (red circles) of the recent earthquakes that generated tsunami event. Page 5 of 110 1.5 Tsunami Early Warning System in Malaysia In 2005, the Malaysian government decided to set up the Malaysian National Tsunami Early Warning System to overcome the lack of capability in carrying out tsunami watch and the issuance of early warning for tsunami in the nation. The set up of the Malaysian National Tsunami Early Warning System is based on the following key features (Low, 2005): 1. Maintaining real-time continuous monitoring of earthquake occurrences and tsunami on a 24-hour basis throughout the year. 2. Issuance of information, advisory, notice, early warning and warning on the occurrence of earthquake and tsunami that threaten the security and safety of Malaysia. 3. The system shall be an integral part of the proposed Indian Ocean Tsunami Warning System to be coordinated by the Intergovernmental Oceanic Commission (IOC), UNESCO. 1.5.1 Overview of the Malaysian National Tsunami Early Warning System The Malaysian National Tsunami Early Warning System consists of 3 major components, namely data and information collection, processing and dissemination (Figure 5). The data and information component comprises data collection networks sub-systems such as seismic network, deep ocean buoy network, tide gauge network, coastal camera network and linkage to Pacific Tsunami Warning Center (PTWC), Japan Meteorological Agency (JMA), Indian Ocean Tsunami Warning System (IOTWS) and other tsunami warning centers. The processing component sub-systems comprises integration and analysis to integrate all the necessary input information, an intelligent decision making as guidance for quick decision making to issue tsunami information or warning, tsunami prediction to expedite the determination of possible occurrence or non-occurrence of tsunami, television and mini-studio for direct broadcasting to the media. The dissemination component is designed to disseminate advisory or warning and other information to the relevant personnel and agencies within 15 minutes after the occurrence of an earthquake. The modes of dissemination are sorted out into dispatching short messages (SMS) to mobile phones, sending telefaxes to relevant disaster management agencies, transmitting relevant information to mass media via broadcasting system, public announcement system such as warning sirens and alarms, transmitting the seismic and tsunami information to the National Disaster Data and Information system (NADDI) located at the Malaysian Remote Sensing Agency (MACRES) and automated updating of the Malaysian Meteorological Department (MMD) earthquake and tsunami web pages. Page 6 of 110 Figure 5. System overview of Malaysian National Tsunami Early Warning System (Low, 2005) 1.5.2 Seismic Network Malaysian Meteorological Department operates a total of 17 seismological stations throughout the country with 10 broadband seismometers (Streckeisen STS-2) and 7 short period seismometers (SS-1 Ranger) as shown in Figure 6. The seismic stations are located at Kulim, Ipoh, Kuala Lumpur, Kluang, Kota Tinggi, Kuala Terengganu, Jerantut, Kuching, Sibu, Bintulu, Bakun, Kota Kinabalu, Kudat, Sandakan, Lahad Datu, Sapulut and Tawau. The current real time digital seismic network is able to detect earthquakes and acquire digital seismic waves from various seismometers and accelerometers. Each remote seismological station is installed with three components weak motion seismometer and strong motion accelerometer (episensor). The real time data is transmitted via VSAT telemetry using 256 kbps digital leased line communication from the service provider‟s satellite gateway to the central processing center in headquarter of MMD for processing, analysis and dissemination. The central processing center runs Boulder Real Time Technologies (BRTT) Antelope system as processing software on SUN Blade for real time and post processing base. BRTT provides software which supports the collection, archiving, integration, and processing of environment sensors, particularly seismic sensors. The Antelope Real Time System (ARTS) is providing automatic and manual event detections, arrival picking, locations and magnitude calculation. MMD is also using SeismComP3 and EarlyBird processing software for comparison with Antelope. Apart from that, MMD also operates a total of 10 strong motion stations had been installed in Klang Valley area. The strong motion stations are located at Gohtong Jaya, Shah Page 7 of 110 Alam, Bukit Kiara, Dusun Tua, Serendah, Ulu Yam, Beranang, Kundang, Janda Baik and Putrajaya. Figure 6. Locations of seismic stations in Malaysia. (Blue triangles: stations with Streckeisen STS-2 seismometers, yellow triangles: new stations with Streckeisen STS-2 seismometers, green triangles: stations with SS-1 Ranger seismometers) (e.g. Zamuna, 2009) 1.5.3 Tide Gauge Network The tide gauge stations should be situated at strategic locations such as the one facing the open sea, where tsunami waves should not be high, with easier national leveling network connection and outcropped bedrock without accumulation of sand or mud and effective for warning purposes (Shiraihi, 2008). For the case of local tsunamis, many tide gauges are needed along the coastlines to get real time confirmation and evaluation of tsunami waves. The location of the sea level gauges plays an important role in tsunami warning particularly in prediction of tsunami occurrences, monitoring in progress of tsunami and estimation of severity of tsunami along the coasts. The total of 6 tide gauge stations (Table 2 and Figure 7) had been installed in strategic locations, and serve as the first line monitoring system to detect the rise and fall of sea water levels. The INMARSAT satellite communication is used for real time data transmission to the central processing center in headquarter of MMD for analysis. In a normal mode, the data transmission cycle is every 1 hour and only one averaged value of the data in the last 15 minutes is transmitted. In case where the sea level change exceeds the set threshold or tsunami generation is expected than usual normal mode, then the system will automatically or remotely changed to tsunami mode. In a tsunami mode, the data transmission is done every 1 minute and only one Page 8 of 110 averaged value of the data in the last 15 seconds is transmitted. Currently, MMD also collects sea-level data from 79 overseas tidal stations in near-real time via WMO and GTS circuit. An additional of 15 new tide gauge stations will join the current National Tide Gauge Network in near future. Table 2. List of tide gauge stations operated by MMD (MMD, 2009b) Location Name Longitude Latitude 0 Porto Malai, Langkawi 99.76 E 6.240N Pulau Perak, Kedah 98.920E 5.710N 0 Pantai Kerachut, Penang 100.20 E 5.450N Pulau Perhentian, Terengganu 102.700E 5.930N Kudat, Sabah 116.850E 6.900N 0 Lahad Datu, Sabah 119.09 E 5.050N Figure 7. The location of existing and future tide gauge stations. 1.5.4 Deep Ocean Buoy Network The Malaysian deep ocean buoy network consists of three (3) operational data buoys (Figure 8 and Table 3) with seabed mounted tsunami detection modules and has been deployed at the strategic locations. The first tsunami buoy of Malaysia was installed near the Rondo Island, Sumatra, Indonesia on 30 December 2005 and the second tsunami buoy was installed on 7 March 2006 near the Layang-Layang Island (Shallow Reef), Sabah in the South China Sea region. The last tsunami buoy will be installed in the Sulu Sea region to provide early warning on tsunami generation near the Philippines and Sulu Sea (MMD, 2009b). The detailed information of the deep ocean buoys are described in Table 3. Page 9 of 110 Buoy 3 Buoy 2 Buoy 1 Figure 8. The locations of Malaysian Deep Ocean buoy (MMD, 2009b). Table 3. List of name and location of Malaysian Deep Ocean buoys (MMD, 2009b). Buoy name Location Name Longitude, Latitude Buoy 1 Rondo Island, Indonesia 95.100E, 6.100N Buoy 2 Layang-Layang Island, Malaysia 113.790E, 7.370N Buoy 3 Sulu Sea To be installed The position of the buoys is based on the study that would maximize the lead time for the states to issue a warning to the communities in coastal areas. The Malaysian deep ocean buoys are equipped with bottom pressure sensor positioned in the deep ocean that is able to detect the early passing of tsunami before it reaches shallow waters and causes destruction along the coastlines. The buoys data are then transmitted via satellite communication system (INMARSAT) to the server provided at the Malaysian National Tsunami Early Warning Center, MMD. In a normal mode, the data transmission cycle is every 1 hour and only one averaged value of the data in the last 15 minutes is transmitted. When the sea level change exceeds a set threshold or tsunami generation is expected than usual normal mode, then the system will automatically or remotely change to tsunami mode. In a tsunami mode, the data transmission is done every 15 seconds and only one averaged value of the data in the last 15 seconds is transmitted. Apart from that, MMD also collects sea-level data from 18 overseas NOAA Dart buoys in near-real time via WMO and GTS circuit. 1.5.5 Coastal Camera Network Currently, a total of 4 coastal cameras had been installed in the strategic locations along the coastlines of northern parts of Peninsular Malaysia at Batu Feringgi, Pasir Panjang and Kuala Muda in Penang and Pantai Chenang in Langkawi Island, Kedah to provide vital information on sea conditions at the coastal areas (Figure 9). In the near future, MMD will enhance the capability of the coastal camera network by adding a total of 14 coastal cameras into the existing network. Page 10 of 110 Figure 9. The location of existing and future coastal cameras. 1.5.6 Tsunami Siren Warning Network Currently, a total of 13 warning sirens had been installed in the populated coastal areas and beaches along the coastlines of Malaysia (Figure 10). The siren network is intended to provide notification of an emergency to warn and ensure public safety within the affected areas. In the near future, MMD will add a total of 10 warning sirens into the existing network. Figure 10. The location of existing and future warning sirens. Page 11 of 110 1.5.7 Disaster Alert System (DAS) Disaster alert system is a fixed lines alert system (FLAS) to deliver voice messages via fixed telephone line to the public in the affected areas. FLAS enables the Malaysian National Tsunami Early Warning centre to perform mass broadcast of alert voice messages by making outbound calls to TM‟s fixed line subscribers. FLAS is able to broadcast alert messages to a large volume of recipients. FLAS supports outbound call to states, districts, towns and area based on the user selection according to the identified tsunami risk areas. 1.6 Review and Purpose The study on Tsunami Early Warning System in Malaysia to issue tsunami warning using precomputed scenarios database was carried out by Norhadizah (2007). This study is emphasis on how to make the database for tsunami using the tsunami simulation results as pre-computed scenarios. This study also introduces entering data into the database, retrieving data from the database, and then applying to the Tsunami Early Warning System for issuance of the warning. The study of appropriate modeling of tsunamis in Malaysia for risk evaluation had been carried out by Zaty (2007) using numerical method of tsunami simulation with the staggered leap-frog scheme (TUNAMI) developed by Disaster Control Research Center, Tohoku University, Japan. A prototype database for Tsunami Early Warning System with Data Assimilation in Malaysia was undertaken by Chai (2008). This study was a refinement to the procedures especially in retrieving data from database and cancellation of tsunami warning. This study has developed a practical forecast system that combines real seismic and tsunami data with a forecast database of pre-computed scenarios as guidance tools during the actual tsunami event. The purpose of this study is to develop a tsunami database for the National Tsunami Early Warning Centre of Malaysia (MNTEWC) in parallel to the implementation plan of Regional Tsunami Watch Providers (RTWP). In order to reach the status of RTWP by 2011, the MNTEWC should develop 3 Service Levels capabilities to provide tsunami advisories over the Indian Ocean countries through bilateral arrangements. Service Level 1 is the service level provided by the Interim Advisory Service for event analysis and provision of a series of advisories from the initial assessment. Service Level 2 is a more robust service level that includes all the elements of Service Level 1 but adds modeling and forecast. Service Level 3 links the Service Level 2 services and products with local risk, hazard assessment and inundation models through National Tsunami Warning Centers (NTWCs) to provide coastal inundation forecast for communities at risk. 1.7 Scope of Study Area The scope of study area covers the region from 500S to 400N and 100E to 1500E in latitude and longitude, respectively, which covers wider areas in Indian Ocean, Pacific Ocean, Andaman Sea, Philippines Sea, South China Sea, Sulu Sea, Celebes Sea and Banda Sea. Page 12 of 110 2. DATA 2.1 Bathymetry Data The General Bathymetric Chart of the Oceans (GEBCO One Minute Grid, approximately to 1850 m) is downloaded from the Internet at http://www.gebco.net, and drawn in three dimensions chart (Figure 11) by Generic Mapping Tool software (Wessel and Smith, 2007). In tsunami numerical simulations, the accurate bathymetric data is essential and plays important roles because the phase velocity of the tsunami wave depends on the water depth (Fujii and Satake, 2006). This original bathymetric data is then modified to 2 and 5 arc-minute of spatial grid sizes, approximately to 3700 and 9250 m, respectively. On the other hand, this bathymetry data is also used to calculate tsunami travel times by using TTT software and waveforms at the outpoint points. Figure 11. Bathymetry chart of the study area in three dimensions. Page 13 of 110 3. THEORY 3.1 Causes of Tsunami Tsunamis are water waves generated by the disturbance caused by submarine earthquakes, landslides, explosive volcanism and large meteorite impact with the ocean. The major cause of tsunami generation in the Pacific Ocean over the last 200 years is due to earthquakes generated in a subduction zone, an area where plate tectonic forces are forcing an oceanic plate down into mantle. When the energy accumulates in the overriding plate exceeds the frictional forces between the two struck plates caused the overriding plate spans back into an unrestrained position. This sudden motion is the cause of the tsunami because it gives an enormous shove to the overlying water. Tsunami generation depends on several factors such as magnitude, depth, faulting and rupture of ocean bottom. Most of the earthquakes with magnitude more than 7.9 will cause destructive local tsunami near the epicenter and significant sea level changes causing severe damages at great distances (Chadha, 2007). Shallow submarine earthquake events (<100 km) could cause the vertical displacement of ocean bottom to generate tsunami rather than deeper events (>100 km). Thus, earthquakes with thrust or normal fault mechanism are most likely to generate a tsunami rather than a strike slip fault. 3.2 Ocean Bottom and Sea Surface Displacements During the generation of phase, an ocean bottom disturbance due to an earthquake reshapes the sea surface into a tsunami. The initial conditions at ocean bottom and surface water differ by factor of 1 / cosh kd , where k and d is wave number and water depth, respectively. When the wavelength ( ) is much larger than 2d ( 2d ) the factor of 1 / cosh kd is approaching 1. Hence, sea surface displacement is the same as the ocean bottom displacement by assuming that the wavelength of the ocean bottom deformation is much larger than the water depth (Kajiura, 1963). 3.3 Propagation of Near-field Tsunamis Propagation of near-field tsunamis, the waves of which propagate less than 1,000 km distances, could be considered on a Cartesian coordinate system in numerical simulations. The computational area for tsunami simulation in near-field tsunamis is small compared with computational area for far-field tsunamis. Thus, for better results in numerical simulation, Cartesian coordinate system is applicable. Page 14 of 110 3.3.1 Governing Equation in Cartesian Coordinate System The shallow water approximation assumed that the vertical acceleration of water particle is negligible compared to the gravitational acceleration except for an oceanic propagation of tsunami (Kajiura, 1963). Thus, the vertical motion of the particles has no effect on the pressure distribution assuming that pressure is hydrostatic. For the case of tsunami propagation in shallow water, the horizontal eddy turbulence is negligible compared to the bottom friction except for run-up on the land. The fundamental equations of continuity and momentum in two dimensional for Cartesian coordinate system can be expressed by following equations (Imamura, 1995): M N 0 t x y M M 2 MN x 0 gD t x D y D x N MN N 2 y gD 0 t x D y D y (1) where x and y are horizontal axes, t is time, η is the vertical displacement of water surface above the still water surface, g is the gravitational acceleration, D is the total water (D = h+ η), τx and τy are the bottom frictions in the x and y directions, respectively and ρ is density. M and N are the components of discharge fluxes in the x and y directions which are given by, M udz u(h ) uD h N vdz v(h ) vD (2) h where u and v are water particle velocities in the x and y directions, respectively, while η and h are the vertical displacement of water surface above the still water surface and still water depth, respectively. 3.3.2 Bottom Friction Term The analogy of the uniform flow, the bottom friction is generally expressed by following equations (Imamura, 1995): x gn 2 M M2 N2 D 73 (3) y gn N M2 N2 D 73 2 where n is Mannings‟s roughness. Page 15 of 110 ( 2 ) ( 3 ) The relation between friction coefficient f and n are described by the following equation (Imamura, 1995): n fD1 / 3 2g (4) The n should be selected depending on the condition of the bottom surface (Table 4). Table 4. The coefficient values of the Bottom Friction n (Linsley and Franzini, 1979) Channel Material n Neat cement, smooth metal 0.010 Rubble masonry 0.017 Smooth earth 0.018 Natural channels in good condition 0.025 Natural channels with stones and weeds 0.035 Very poor natural channels 0.060 3.4 Propagation of Far-field Tsunamis Propagation of far-field tsunamis are described as waves which propagate more than 1,000 km over the ocean and in numerical simulations should be considered polar coordinate system (Shuto, 1997). The physical dispersion wave of tsunami cannot be neglected when tsunami energy travels in a long distance over the ocean. Propagation of tsunamis in long distance should consider the effects of earth‟s sphere and rotation due to Coriolis force. In this study, for far-field tsunamis that propagate across a large ocean, the linear long wave theory is used in spherical coordinates system (R, , ) where R is radius of the earth, is co-latitude measured from North Pole (Ω) to south and is longitude measured to the east from Greenwich Meridian (Figure 12). Ω R Figure 12. The spherical coordinates system for rotating earth (e.g. Zaty, 2007). Page 16 of 110 ( 4 ) 3.4.1 Governing Equation in Spherical Coordinates System The integrated equations for linear long wave theory on the rotating earth in the spherical coordinates system must consider the Coriolis force effect, which is used in the computation of trans-oceanic tsunami propagation by following equations (Nagano, 1991): 1 M ( N cos ) 0 t R cos M gh fN 0 t R cos (5) N gh fM 0 t R In which is the water surface elevation, M and N are discharge fluxes along the latitude and longitude , h is the water depth, f is the Coriolis parameter ( f 2 sin ), g is the gravitational acceleration and R is radius of the earth. 3.5 Ocean Bottom Deformation The dislocation of the ocean bottom can be calculated from those fault plane parameters (Figure 13) using the elastic theory given by Okada (1985). If an earthquake occurs in the level deeper than 100 km under the ocean bottom, no lift will take place on the ocean bottom and tsunami will not be generated. Usually, only the vertical component of the ocean bottom is considered for tsunami generation. When the tsunami source is on a steep ocean slope and the horizontal displacement is large, the vertical displacement of the water due to the horizontal displacement of the slope must be considered (Tanioka and Satake 1996a). To compute the surface deformation, the fault parameters such as fault location, geometry (strike, dip and rake), size (length L and width W) and average slip u need to be defined first. The seismic moment Mo is given as M 0 uS uLW (6) where S is the fault area and is rigidity. Thus, the moment magnitude is defined as MW log M 0 9.1 1.5 (7) Page 17 of 110 ( 5 ) Figure 13. Fault plane parameters (Satake, 2008). 3.6 Scaling Law Scaling law theory is used to determine the fault size parameters such as length, width and slip amount (Tatehata, 1997). This theory is useful to calculate the parameter of earthquake events, which is controlled by moment magnitude. The equations of scaling law theory are expressed as follows: log L 0.5M W 1.9 L W 2 logU 0.5M W 1.4 (8) ( 6 ) Here, L is length (km), W is width (km), U is slip amount (cm) and Mw is moment magnitude. 3.7 Green’s Law The Green‟s Law is applied to estimate the reliable tsunami heights for coastal point from the forecast point at the sea using conservation theory of potential energy along the rays by assuming that there is no reflection, no energy loss and small wave heights (e.g. Satake, 2008). The tsunami height at coastal points can be defined as b h0 1 b0 1 2 d1 d0 1 4 h1 (9) where, b0 and b1 are distances between the rays at the coastal and forecast points, h0 and h1 are tsunami heights at the coastal and forecast points and d0 and d1 are water depths at the coastal Page 18 of 110 ( 7 ) and forecast points, respectively. This law is only applicable to direct waves and is not taken into account for the reflected waves or edge waves. If the tsunami wave front at the forecast point (h1, d1) is parallel with the coastal point (h0, d0), the ratio of b1 / b0 is assumed as 1. Then, the equation (9) is simplified to d h0 1 d0 1 4 h1 (10) 3.8 Numerical Model The finite difference method is used to discrete expression of approximation of the differential equation and is extensively used for numerical analysis to solve differential equations. In the finite difference method, mainly three forms of differences such as forward, backward and central are considered. The expression of the finite difference is similar but the order of errors is different. The forward difference and backward difference have an error of the first order and central difference has an error of second order. 3.8.1 Staggered leap-frog Scheme In the numerical modeling of tsunami, the governing equations (1) can be discretized by using a staggered leap-frog scheme (Shuto, 1990). Staggered scheme is a grid system to set variables in spatial domain staggeringly. The scalar variable like η is set on the center of a grid, and vector variable like M and N is on the side as shown in Figure 14. Basically, the leap-frog scheme is using central difference to discretize the equation (1) to be solved numerically with truncation errors of the second order. The advantages of the staggered leap-frog scheme are that it is simple, easy to set boundary conditions, provides stable result as long as the Courant condition is satisfied and there is no dissipative error. However, the disadvantages of this scheme are existence of dispersive and second order error. Figure 14. Staggered leap-frog scheme in x-y domain (left) and x-t domain (right). (Imamura, 2006). Page 19 of 110 ( 8 ) The discretization of equation (1) is rather complicated by considering the bottom friction and non-linear terms. The numerical schemes of TUNAMI code for shallow water equations in two dimensions Cartesian coordinate system for linear term without considering the non-linear and bottom friction terms can be summarized as follows (Koshimura, 2008): ik, j 1 ik, j t t k 1 / 2 M ik11/ /22, j M ik11/ /22, j N i , j 1 / 2 N ik, j 11/ /22 x y M ik11/ /22, j M ik11/ /22, j g N k 1 / 2 i , j 1 / 2 N k 1 / 2 i , j 1 / 2 D Dik, j t k i 1, j 2 D g k i , j 1 x Dik, j t 2 y k i 1, j k i , j 1 ik, j (11) ik, j Here, t and x are corresponding to temporal and spatial grid sizes respectively, subscript i and k represent the spatial grid number x i x and time t k t , respectively. Numerical schemes of TUNAMI code of equations (5) for linear long wave theory in spherical coordinates system through Figure 15 can be summarized as follows (Shuto, 1997): M n11 M n 1 j ,m 2 j ,m 2 t n 1 n 1 j ,m2 j ,m2 t gh 1 j ,m 2 t 1 n 1 M n 1 M n 1 N n 1 cos 1 N n 1 cos 1 j , m j , m j ,m m j ,m m 1 2 2 2 2 2 2 0 R cos m N n 11 N n j ,m 2 n j 12,m j ,m2 f n n n n N 1 N 1 N 1 N 1 0 j 1, m j ,m j ,m R cos m 4 j 1,m 2 2 2 2 1 j ,m 2 gh 1 j ,m 2 R sin m 1 2 j , m 1 n 1 2 j ,m n f 4 (12) n n n n M j 1 ,m 1 M j 1 ,m M j 1 ,m1 M j 1 ,m 0 2 2 2 2 2 Here, a point of computation is numbered as ( j , m, n ) in the ( , , t ) directions, and are computation grid lengths in the latitude and longitude directions, respectively. R is the radius of the earth, g is the gravitational acceleration, h is the water depth, and f represents the Coriolis force coefficient due to the rotation of the earth. Page 20 of 110 ( 1 0 ) Figure 15. Computation point for water level and discharge (Shuto, 1997). 3.8.2 Numerical Stability To perform the calculation in a stable and reasonable way by considering the CFL (Courant Friedrics Lewy) condition given by the following formula (Imamura, 2006): t x 2ghmax (13) Here, x is spatial grid size, Δt is temporal grid size, g is gravity acceleration (9.8 m/s2) and hmax is the greatest sea depth in the calculated area. If the temporal grid size was set at more than the CFL condition, the numerical simulations would result with instability. 4. METHODOLOGY 4.1 Tsunamigenic Earthquake Locations The locations of the tsunamigenic earthquake are searched through Global Centroid Moment Tensor Project catalog search from the year 1976 until 2008 which is downloaded from the Internet at http://www.globalcmt.org/CMTsearch.html. The depths are from 0 to 100 km and magnitudes from 6.5 to 10 considering that the most possible tsunami can occur due to an earthquake. Epicenters are chosen within 100E to 1500E and 500S to 400N in longitude and latitude, respectively (Figure 16). Comparison at the same criteria for depths and magnitudes are made with other searches of tsunami databases taken from Integrated Tsunami Database for the World Ocean (WinITDB, 2007) and National Geophysical Data Center (NGDC) Tsunami Event Database at http://www.ngdc.noaa.gov which covered the wider data. However, these databases showed insufficient information available on the fault parameters. Thus, comparisons of the fault Page 21 of 110 ( 1 1 ) parameters from Global CMT Project catalog with these databases are made in terms of location, magnitude and depth to determine the locations of tsunamigenic earthquake. Figure 16. Location of tsunamigenic earthquake events from Global CMT Project catalog search (focal mechanisms), WinITDB (red stars) and NGDC (blue triangles) drawn by using GMT commands in two dimensions bathymetry data of study area. The results had almost similarity in that the locations of the tsunamigenic earthquake are located along the subduction zones and fault lines. However, an earthquake that occurred along the fault lines is unlikely to generate tsunami due to strike-slip fault mechanism. The main concern is the shallower earthquakes occurring along the subduction zones have high possibility to generate tsunami due to the reverse fault mechanism. Page 22 of 110 4.2 Magnitude and Depth The magnitude and depth are set based on the historical earthquake events which are taken from Global Centroid Moment Tensor Project catalog search, Integrated Tsunami Database for the World Ocean (WinITDB, 2007) and National Geophysical Data Center (NGDC). Comparison is made in terms of magnitudes and depths (Figure 17). The minimum magnitude of 6.5 is set based on the MMD tsunami warning criteria when distant tsunami hazard more than 200 km from Malaysian coastline exists (e.g. Saw, 2007). Since the distributions of magnitude and depth are denser between Mw6.5 to Mw8.5 and shallower than 60 km therefore, the interval of magnitude and depth are chosen as described in Table 5. Figure 17. Distribution of magnitudes (horizontal axis) and depths (vertical axis) Table 5. The list of magnitudes and depths are based on historical earthquake events. Magnitude (Mw) Depth (km) 6.5 0 7.0 20 7.5 40 8.0 60 8.5 Page 23 of 110 4.3 Source Points By definition, the source point is defined as the center of tsunami source and equivalent to center of the fault in width and length of the earthquake. The location of the source points is chosen among the earthquake source areas searched through historical earthquake events from Global CMT Project catalog search and WinITBD (Figure 16). The source points are located along the most active subduction zones (Figure 18). Each source point is located on the grid point with distance interval of 30 arc-minutes (~50 km) along the earthquake sources. The total numbers of source points for each model of TUNAMI-F1 and NAMI-DANCE is 1547, and 181 for TUNAMI-N2 with 5 magnitudes (Mw 6.5, 7.0, 7.5, 8.0 and 8.5) and 4 depths (0, 20, 40 and 60 km). This means that one source point consists of 20 scenarios. Therefore, the total of scenarios for each model of TUNAMI-F1 and NAMI-DANCE is 30940 and 3620 for TUNAMI-N2. Figure 18. Epicenters of theoretical earthquakes with differential by strike angle. Page 24 of 110 4.4 Forecast and Coastal Points The forecast points are located along the bathymetric contour depth of 50 m with random interval distance between each point as shown in Figure 19. The forecast points (red triangles in Figure 19) are located along the coastal area which is defined as output point in tsunami numerical simulations. According to JMA, the forecast point of 50 m is chosen considering the effects of the non-linear term in shallow water theory. The coastal points are located at 1 m bathymetric contour depth along the coastlines because we clipped the water depth in bathymetry data at minimum to 1 m. The coastal points (blue circles in Figure 19) are placed along the coastlines with random interval distance. The location of coastal points is determined and searched using Google Earth (2009) considering the most vulnerable areas for tsunami impacts, denser population areas and tourism attractions. In order to represent the spreading of ray equivalent to 1, the forecast and coastal points are situated in parallel position to each other along the rays. Thus, the tsunami heights at the coastal points are then estimated by Green‟s Law theory based on the tsunami heights at forecast points with bathymetric contour depths of 50 m. Neither forecast nor coastal point which is not located in the grid point of the bathymetry contour depth as mentioned above due to the complexity of the coastal bathymetry. The nearest grid point of the bathymetry contour depth is selected to locate the forecast point or coastal point. Figure 19. Location of the coastal points (blue circles) and forecast points (red triangles). Page 25 of 110 4.4.1 Green’s Law In numerical simulations, using the finer grid is essential to estimate the accurate tsunami heights especially in shallow waters as the phase velocity of tsunami wave depends on the water depth (Fujii and Satake, 2006). In numerical simulations, if we use bathymetry data of 1, 2 and 5 arcminute, it is less reliable to estimate the tsunami heights at the coastal points. In order to avoid longer computation of tsunami propagation in shallow waters and underestimation of tsunami heights at coastal points, the Green‟s Law calculation is applied. Green‟s Law calculation using equation (10) is applied to obtain the reliable tsunami height at the coastal points based on the maximum tsunami height at the forecast points with bathymetric contour depth of 50 m. In this case, the forecast point and coastal point are situated in parallel position to each other, so that the ratio of b1 / b0 in equation (9) is assumed as 1 (Figure 20). Figure 20. Forecast point (green circle) and coastal point (red circle) are situated in parallel position to each other. Page 26 of 110 4.5 Initial Condition Tsunami source is a center of fault in width and length and defined as center of fault (COF). In tsunami numerical simulations the input of tsunami source is at top left corner (TLC) as shown in Figure 21. The strike angle ( ) assumed to be parallel to the trench axis. Dip angle (δ) and rake angle (λ) are assumed as 450 and 900, respectively for the most credible worst case of tsunami event. Figure 21. Fault plane parameters. Red dashed line indicated as depth of center fault (DCF). 4.5.1 Depth of Top Left Corner The depth of TLC (Figure 22) can be calculated from depth of center fault by following equation: W (14) sin 2 is depth of TLC, DCF is depth of center fault, W is width and δ is dip angle. d TLC DCF Here, d TLC Figure 22. Vertical cross section of fault plane. Red star indicated the center of fault and X is the distance from TLC and perpendicular with DCF. Page 27 of 110 ( 1 2 ) 4.5.2 Location of Top Left Corner The location of the TLC can be calculated based on the location and depth of the COF. Figure 23 shows the top view of the fault plane in Figure 22. Figure 23. Top view of the fault plane in Figure 19. Red star indicated the center of fault (COF) The change of longitude ∆x and latitude ∆y to obtain the location of TLC is defined as R x cos 110.226 180 (15) R y sin 110.578 180 2 ( 1 3 ) 2 X L X which is strike direction, X = Wcosδ, tan and R = 2 2 L The coefficients value of 110.226 and 110.578 are corresponding to length (km) per 1 degree for longitude and latitude, respectively. These coefficients value are based on 80N in latitude. The location of COF moves to east and south. Thus, TLC location can be calculated based on the following equations: 180 1 LongitudeTLC = LongitudeCOF + ∆x LatitudeTLC = LatitudeCOF - ∆y (16) Page 28 of 110 ( 1 4 ) 4.5.3 Ocean Bottom Deformation An initial profile of tsunami source is assumed to be the same as a deformation of ocean bottom due to earthquake when the wavelength of the ocean bottom is much larger than the water depth (Kajiura, 1963). Elastic theory (Okada, 1985) is used to calculate the static deformation of the ocean bottom due to fault motion (Figure 24). Figure 24. The deformation area of the source point at COF 96.50E and 10N in longitude and latitude (green star), respectively with Mw8.5 and 0 km. Green circle is TLC. Blue and red contours represented as subsidence and uplift of the sea bottom deformation, respectively with 0.1 m of contour interval. Page 29 of 110 In this study, single segment is applied to all the source points. Fault parameters model (Table 5) is used for each source point at different magnitudes and depths. For the case in which depth of TLC has negative value, the depth is forced to be 10.000 km considering that tsunami source must be located at or beneath the ocean bottom but not in the upper part of the ocean bottom. Other parameters such as slip amount, length and width are determined by Scaling Law theory. These fault parameters are used as the initial condition for model source to calculate tsunami propagation over the ocean. Table 5. Fault parameters for selected source point at different magnitudes and depths. Depth of DCF TLC Length Width Strike Dip Rake (km) (km) Slip (cm) (km) (km) (deg) (deg) (deg) Mw 6.5 6.5 6.5 6.5 7.0 7.0 7.0 7.0 7.5 7.5 7.5 7.5 8.0 8.0 8.0 8.0 8.5 8.5 8.5 8.5 0 20 40 60 0 20 40 60 0 20 40 60 0 20 40 60 0 20 40 60 10.000* 15.238 35.238 55.238 10.000* 11.531 31.531 51.531 10.000* 10.000* 24.94 44.94 10.000* 10.000* 13.219 33.219 10.000* 10.000* 10.000* 12.377 70.8 70.8 70.8 70.8 125.9 125.9 125.9 125.9 223.9 223.9 223.9 223.9 398.1 398.1 398.1 398.1 707.9 707.9 707.9 707.9 22.4 22.4 22.4 22.4 39.8 39.8 39.8 39.8 70.8 70.8 70.8 70.8 125.9 125.9 125.9 125.9 223.9 223.9 223.9 223.9 11.2 11.2 11.2 11.2 19.9 19.9 19.9 19.9 35.4 35.4 35.4 35.4 62.9 62.9 62.9 62.9 111.9 111.9 111.9 111.9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 Remark: * Depth of TLC has negative value and forced to be 10.000 km. Strike angle ( ) is the angle measured counter-clock-wise from the local north to the strike direction. Dip angle (δ) is the angle between the mean earth surface and the fault plane, measured from the mean earth surface down to the fault plane. Rake (λ) describes to which direction the hanging block moves relative to the foot block on the fault plane. Page 30 of 110 4.6 Inverse Tsunami Travel Times Tsunami Travel Times (TTT) software was developed by Dr. Paul Wessel and is distributed as a commercial product in Geoware online. This software works on several platforms including Windows, Linux, UNIX and Mac OS. In this study, TTT software package version 1.12 is used which was provided free of charge by NOAA‟s National Geophysical Data Center as the World Data Center (WDC) for Solid Earth Geophysics-Tsunamis collaborated with the IOC‟s International Tsunami Information Centre (ITIC) which runs on Cygwin in Windows platform. Basically, TTT is able to calculate tsunami travel times on all of the grid points from the supplied bathymetric data using Huygen‟s principle on a geographic latitude and longitude grid (e.g. Fujii, 2008). Since the original GEBCO data (1 arc minute) has positive values on land grid and the grid format is NetCDF, a conversion into “i2” format is needed for TTT calculations. Output grid file suffix in „.b‟ and written in unit of minute. So, the contour interval is in minute. In TUNAMI-F1 and TUNAMI-N2, the tsunami travel times are inversely calculated from the coastal point to tsunami source (Figure 25) using GMT options. The purpose is to calculate the minimum predicted value of tsunami travel time from coastal point to the grid points of tsunami source area (equivalent to sea bottom deformation area). The grid points of those within the tsunami source, and have absolute value as shown in Table 6 are considered as initial points. The minimum value of tsunami travel time from coastal point to the grid point of tsunami source area is selected as tsunami arrival time. Since the same method is not applicable to calculate the tsunami travel times from coastal points to the tsunami source area due to the different output file format, thus, in NAMI-DANCE, the tsunami travel time is calculated from the coastal point to the center of fault of the tsunami source point (Figure 26). In this case, for the same source point the tsunami travel time is the same because this method doesn‟t consider the effects of magnitude and sea bottom deformation area. The tsunami arrival time which is obtained by the inversion of tsunami travel times are then stored into database as tsunami arrival time at coastal points. Table 6: The absolute value of the tsunami source area against magnitude Magnitude (Mw) Tsunami source 6.5 > 0.01 m 7.0 > 0.02 m 7.5 > 0.03 m 8.0 > 0.05 m 8.5 > 0.1 m Page 31 of 110 Figure 25. Inverse tsunami travel time diagram from coastal point (green triangle) to nearest tsunami source area point which has absolute value greater than 0.1 m (red dots) with contour interval of 10 min. Green star is the COF. The value of 229 is the tsunami arrival time in minutes. Page 32 of 110 Figure 26. Inverse tsunami travel time diagram from the coastal point (green triangle) to the center of fault (green star) of the tsunami source point with contour interval of 10 min. The value of 244 is the tsunami arrival time in minutes. Page 33 of 110 4.7 Tsunami Numerical Simulation Models We used a benchmarked and validated open ocean propagation model and bathymetry according to the Intergovernmental Coordination Group for the Indian Ocean Tsunami Warning and Mitigation System (ICG/IOTWS) Working Group 4 (WG4) recommendations (IOC, 2008). This study used three different types of numerical simulation models namely TUNAMI-F1, TUNAMI-N2 and NAMI-DANCE version 4.7 to calculate the tsunami propagation over the ocean. For the propagation of the tsunamis over the large ocean, TUNAMI-F1 and NAMIDANCE version 4.7 are used to calculate the tsunami propagation in spherical coordinates system over the Indian Ocean, Pacific Ocean, Andaman Sea, Philippines Sea, South China Sea, Banda Sea, Sulu Sea and Celebes Sea. However, for near field tsunamis, TUNAMI-N2 and NAMI-DANCE version 4.7 are used to calculate the tsunami propagation in the Cartesian coordinate system over the Sulu Sea and Celebes Sea. 4.7.1 Numerical Simulation by TUNAMI-F1 TUNAMI-F1 (Tohoku University‟s Numerical Analysis Model for Investigation of Far-field tsunamis, No.1) is applied to linear theory for tsunami propagation over the ocean in the spherical coordinates system. In this study, the crustal deformation of the ocean bottom is followed the elastic theory of Okada, 1985 and tsunami propagation over the oceans using tunami code which was modified by Associate Prof. Shunichi Koshimura from Disaster Control Research Center, Graduate School of Engineering, Tohoku University of Japan. Tsunami propagation initiated at each fault is calculated based on governing equation (5) were numerically solved by the leap-frog finite-difference scheme (Koshimura, 2008). The dimension of calculation area for tsunami propagation over the Indian Ocean and Andaman Sea are 1681 and 961 grid points for longitude and latitude, respectively. The area of the numerical calculations covers the region from 100E to 1500E in longitude and from 500S to 300N in latitude. The temporal interval (Δt) is 6 s for computation which was less than Courant Friedrics Lewy (CFL) stability condition determined by equation (13). The value of temporal interval (Δt) is 20.3 s when spatial grid size (x) is 9250 m, gravity acceleration (g) is 9.8 m/s2 and the greatest sea depth in the calculated area ( hmax ) is 10559 m. For the other regions such as Pacific Ocean, Philippines Sea, South China Sea, Banda Sea, Sulu Sea and Celebes Sea that cover the region from 900E to 1500E in longitude and 200S to 400N in latitude, the dimension of calculation area is 1801 grid points for longitude and latitude. The temporal interval is 6 s for computation. The value of temporal interval (Δt) is 8.1 s when spatial grid size (x) is 3700 m, gravity acceleration (g) is 9.8 m/s2 and the greatest sea depth in the calculated area ( hmax ) is 10563 m. The calculation time of numerical simulation is set to 24 hours considering that the arrival of tsunami and time of maximum tsunami height can reach at coastal points within this period. 4.7.2 Numerical Simulation by TUNAMI-N2 TUNAMI-N2 (Tohoku University‟s Numerical Analysis Model for Investigation of Near-field tsunamis, No.2) is applied to shallow water theory for propagation over the ocean in the Cartesian coordinates system. In this study, the crustal deformation of the ocean bottom is following the elastic theory of Okada, 1985 and using tunami code, which was modified by Page 34 of 110 Shunichi Koshimura from Disaster Control Research Center School of Engineering, Tohoku University of Japan, to calculate the tsunami propagation over the Cartesian coordinate system. Tsunami propagation initiated at each fault is calculated based on governing equation (1) that were numerically solved by the leap-frog finite-difference scheme (Koshimura, 2008). The dimension of calculation area for tsunami propagation over the Sulu Sea is 841x841 grid points for longitude and latitude that covers the region from 1140E to 1280E in longitude and from 20N to 160N in latitude. The temporal interval is 3 s, and spatial grid size is 1 arc-min approximately to 1850 m. For Celebes Sea, the dimension of calculation area is 901x901 grids points for longitude and latitude that covers the region from 1140E to 1290E in longitude and from 30S to 120N in latitude. The temporal interval is 3 s and spatial grid size is 1 arc-min (approximately to 1850 m). The calculation time of numerical simulation is 12 hours considering that the arrival of tsunami and the time of maximum tsunami height can reach at the coastal points is within this period. 4.7.3 Numerical Simulation by NAMI-DANCE This code named NAMI-DANCE version 4.7 is initially prepared for the use of Astronautic Technology Sdn. Bhd. (ATSB) Malaysia according to the contract with Middle East Technical University or METU in April 2006. The computational tool of NAMI-DANCE was developed using C++ programming language by Profs Andrey Zatysev, Ahmet Yalciner, Anton Chernov, Efim Pelinovsky and Andrey Kurkin (METU, 2008). This model simulates and animates tsunami generation and propagation in a given arbitrary shaped bathymetry with linear for nonlinear form of shallow water equation with Cartesian or spherical coordinates. The module of co-seismic tsunami generation uses Okada, 1985. The module for tsunami propagation was solved using nonlinear shallow water equation which was given in Shuto, Goto, C., Imamura, F., 1990 and Goto, C., and Ogawa, Y., 1991 used in TUNAMI-N2 which had been authored by Profs. Shuto and Imamura and distributed under the support of UNESCO TIME Project in 1990. In addition to necessary tsunami parameters, this model also computes the distribution of current velocities and direction at the selected time intervals, relative damage levels according to drag and impact forces and prepares 3D plots of sea state at selected time intervals from different camera and light positions and animates the tsunami propagation from source to target. In NAMI-DANCE, propagation of tsunami over the spherical and Cartesian coordinates systems are follows TUNAMI-F1 and TUNAMI-N2, respectively. 4.7.4 Validation Model by TUNAMI-F1 in Spherical Coordinates System The validation model of TUNAMI-F1 for propagation tsunami in the spherical coordinate systems is validated against Bengkulu Tsunami on 12 Sep 2007 (3.78°S, 100.99°E, Magnitude 8.5, depth 24.4 km at 11:11:15 GMT according to CMT). We assumed that the tsunami source is based on the mainshock by Harvard Centroid Moment Tensor (CMT) Project which is strike = 3280, dip angle = 90 and slip angle = 1140. Using the scaling law (Tatehara, 1997) the fault size is 223.9 km x 111.9 km and the average slip on the fault is 7.079 m. The top left corner is 4.903°S, 101.103°E at depth 1.335 km. As the initial condition for tsunami, static deformation of the sea bottom is calculated for a rectangular fault model (Okada, 1985) using the source model (Figure 27). The used bathymetry data is GEBCO resample to 2 arc-minutes and temporal interval is 3 s. Page 35 of 110 Tsunami propagation over the ocean was calculated by using the linear theory equations were numerically solved by using a finite difference scheme (Koshimura, 2008). We selected Padang tide gauge station (1°S, 100.3666°E) as outpoint point in numerical simulation (GLOSS, 2009). We compared the predicted arrival times and tsunami heights at Padang tide gauge station with observation record obtained from the PTWC as describes in Table 7. Figure 27. Deformation area of the Bengkulu Tsunami based on Harvard CMT. Beach ball is the focal mechanism. Blue star is center of fault (COF) and green circle is top left corner (TLC). Blue and red contours represented as subsidence and uplift of the sea bottom deformation, respectively with 0.1 m of contour interval. Table 7: Padang tide gauge observation record from PTWC earthquake bulletin. Arrival time Tsunami Height 1221Z 0.35m 1306Z 0.56m 1348Z 0.98m Page 36 of 110 4.7.5 Validation Model by NAMI-DANCE in Spherical Coordinates System Using the linear theory for propagation tsunami in the spherical coordinates system, NAMIDANCE version 4.7 also validates against Bengkulu Tsunami as mentioned in section 4.7.4. The earthquake parameters are selected similar with TUNAMI-F1 numerical model. The initial condition of the sea bottom deformation is calculated for a rectangular fault model (Okada, 1985) using the source model (Figure 28). Bathymetry data 2 arc-minutes was resampled from the original 1 arc-minute GEBCO. Tsunami propagation in the spherical coordinates system was calculated without considering the Coriolis force and then using a finite difference scheme numerically solved the nonlinear theory equations. We compared the predicted arrival times and tsunami heights of tsunami at Padang tide gauge station with earthquake information bulletin from the PTWC as mention in Table 7. Padang Sumatra Indian Ocean Figure 28. Tsunami source of the Bengkulu Earthquake (NAMI-DANCE Ver. 4.7). Page 37 of 110 4.7.6 Validation Model by TUNAMI-N2 in Cartesian Coordinates System The validation model of TUNAMI-N2 for propagation tsunami in the Cartesian coordinate system is validating against Bengkulu Tsunami on 12 September 2007 (3.78°S, 100.99°E, Magnitude 8.5, depth 24.4 km at 11:11:15 GMT according to CMT). We assumed that the tsunami source is based on the mainshock by Harvard Centroid Moment Tensor (CMT) Project and scaling law, which is strike = 3280, dip angle = 90 and slip angle = 1140. The fault size is 223.9 km x 111.9 km. The top left corner is 4.903°S, 101.103°E at depth 1.335 km. Average slip on the fault is 7.079 m. As the initial condition for tsunami, static deformation of the sea bottom is calculated for a rectangular fault model (Okada, 1985) using the source model (Figure 29). The bathymetry data used is GEBCO 1 arc-minutes (~ 1850 m) and temporal interval is 3 s for computation. Tsunami propagation over the ocean was calculated by using non-linear theory equations were numerically solved by using a finite difference scheme (Koshimura, 2008). Padang tide gauge station (1°S, 100.3666°E, GLOSS) was selected as the outpoint point. The predicted arrival times and tsunami heights at Padang tide gauge station is compared with the observation record obtained from the PTWC as in Table 7. Figure 29. Deformation area of the Bengkulu Tsunami with 0.1 m of contour interval. Light blue star is center of fault (COF) and green circle is top left corner (TLC). Page 38 of 110 4.7.7 Validation Model by NAMI-DANCE in Cartesian Coordinates System Using the non-linear theory for propagation tsunami in the Cartesian coordinates system, NAMIDANCE version 4.7 also validates against 12 September 2007 Bengkulu Tsunami with similar parameters used as mentioned in section 4.7.6. The initial condition of the sea bottom deformation is calculated for a rectangular fault model (Okada, 1985) using the source model (Figure 30). Original GEBCO data with spatial grid size 1 arc-minutes (~1850 m) is used. Tsunami propagation in the Cartesian coordinates system was calculated considering the bottom friction term. We used natural channels in good condition for bottom friction term as 0.025, and then using a finite difference scheme numerically solved the non-linear shallow water equations. The arrival times and tsunami heights of tsunami at Padang tide gauge station are then compared with observation record obtained from the PTWC. Padang Sumatra Indian Ocean Figure 30. Ocean bottom deformation of the Bengkulu Tsunami (NAMI-DANCE Ver. 4.7). . Page 39 of 110 4.8 Tsunami Database Tsunami databases at the Malaysian National Tsunami Early Warning Centre are constructed by MySQL database. MySQL database is the world‟s most popular open source database because of its fast performance, high reliability, ease of use, and dramatic coast savings. MySQL database is an open source relational database management system (RDBMS) based on Structured Query Language (SQL), and works on many different system platforms including Linux, UNIX, Windows and other platforms. The establishment of the reliable and robust tsunami database needs a selection database and systems. This study has adopted a system for developing web application to construct a tsunami database and applied for retrieving. The definition of web application is an application that runs entirely from web browser (such as windows internet explorer and firefox) over a network such as Internet or an intranet. The architecture of tsunami database consists of three main parts namely web server, middleware programming language and relational database (Figure 31). In this study, we used Apache 2.2.11 as web server (http://www.apache.org) and MySQL 5.1.34 for relational database (http://www.mysql.com) works on Linux platform. For middleware scripting language was done by PHP 5.2.9 (http://www.php.net) to connect the web server with relational tsunami database. This software is freely downloaded from the Internet because was distributed as GNU General Public License. Figure 31. Architecture of web applications (Greenspan, 2001) Page 40 of 110 4.8.1 Construction of Tsunami Database The primary step to construct a database is to identify the architecture. Each table consist a set of primary key as a unique identifier. This unique value cannot be NULL and the value remains the same with other table for relationship. A relationship between the two tables mainly applied to this study is one-to-many. In this study, the tsunami database consist more than 30,000 tables, out of which one table for “FP” and “HYP” each, and remaining tables for simulation results. The architecture and relationship between tables are shown in Figure 32. FP table contains the number of forecast points as a primary key, longitude, latitude, depth, name of coastal points, block name (Appendix-1) and country of coastal area. HYP table contains parameter information on case name as a primary key, longitude, latitude, magnitude, depth, strike, dip, rake, length, width and slip. Each table in simulation result contains the number of forecast points as a primary key, case name, arrival time of tsunami and maximum height of tsunami at coastal points. Several temporary tables also had been constructed for retrieving purpose. FP table NO (Identifier case) LON (Longitude of coastal point) LAT (Latitude of coastal point) DEPTH (Bathymetry depth of coastal point) NAME (Name of coastal point) BLOCK (Block of coastal name) COUNTRY (Country of coastal name) HYP table CASENAME (Identifier case) LON (Longitude of the earthquake) LAT (Latitude of the earthquake) MAG (Magnitude of the earthquake) DEPTH (Depth of the earthquake) STRIKE (Strike of the earthquake fault) DIP (Dip of the earthquake fault) RAKE (Rake of the earthquake fault) LENGTH (Length of the earthquake fault) WIDTH (Width of the earthquake fault) SLIP (Slip amount of the earthquake fault) Simulation table -----------------Simulation table---------------------------------- NO (Identifier case) --------------------------CASENAME (Identifier case) ---------ARRIVAL (Arrival time of tsunami NOat coastal point) (Identifier NO MAX (Maximum tsunami height at case) coastal point) (Identifier case) CASE_NAME (Identifier case) CASE_NAME (Identifier ARRIVAL case) (Arrival time of tsunami ARRIVAL (Arrival time at coastal of tsunami point) Figure 32. Architecture of tsunami database. Blue star () is primary key for each table. at MAX_HEIGHT coastal point) (Maximum tsunami MAX_HEIGHT height at (Maximum coastal point) Page 41 of 110 tsunami MAX_TIME height(Time at coastal point) maximum MAX_TIME tsunami 4.8.2 SQL Commands The SQL commands were used in this study based on the MySQL 5.1 reference manual which available on Internet at http://dev.mysql.com/doc/refman/5.1/en. The basic commands of SQL to create a tsunami database with MySQL such as “create database”, “create table for FP, HYP and simulation” and “load data local infile” are described as per below. The describe tables of skema, FP and HYP are shown in Appendix-2. Create a database in MySQL called tunami-f1 CREATE DATABASE tunami-f1; Create a forecast point table called FP CREATE TABLE FP ( No smallint(6) NOT NULL default 0 PRIMARY KEY, Lon float NOT NULL default 0, Lat float NOT NULL default 0, Depth float NOT NULL default 0, Name varchar(50), Block varchar(50), Country varchar(100) ); Create a hypocenter table called HYP CREATE TABLE HYP ( Casename varchar(60), Lon float NOT NULL default 0, Lat float NOT NULL default 0, Mag float NOT NULL default 0, Depth float NOT NULL default 0, Strike float NOT NULL default 0, Dip float NOT NULL default 0, Rake float NOT NULL default 0, Length float NOT NULL default 0, Width float NOT NULL default 0, Slip float NOT NULL default 0 ); Create a simulation table called skema CREATE TABLE skema ( No smallint(6) NOT NULL default 0 PRIMARY KEY, Casename varchar(60) NOT NULL, Arrival float NOT NULL default 0, Max float NOT NULL default 0 ); Insert simulated data from local drive into table called S1_A_M65_D0 which located on server LOAD DATA LOCAL INFILE S1_A_M65_D0.txt' into table S1_A_M65_D0 lines terminated by '\r\n’; Page 42 of 110 4.9 Retrieving from Tsunami Database The important step to perform database retrieving is how quickly and precisely to get the tsunami heights and arrival times from the database. There are several methods to obtain tsunami estimation results from the database such as simple method, interpolation method, extrapolation method and maximum risk method. These methods are performed by combining PHP scripting language and SQL command syntax to retrieve for issuing tsunami information and warning bulletins. 4.9.1 Simple Method Simple method is performing a search to the nearest data point from the determined hypocenter. This method is the easiest way to estimate the heights and arrival times of tsunami from the database. The tsunami height and arrival time of tsunami are selected at the nearest element of data point from the corresponding determined hypocenter as illustration in Figure 33. Table 8 is describes the nearest data point of magnitude and depth for database selection. S 6 S 1 0 S 7 Data point Determined hypocenter x x 1 2 Figure 33. The simple method seeking the nearest data point from the determined hypocenter. Table 8. The nearest selected data point for magnitude and depth of the determined hypocenter Magnitude Data point selection Depth Data point selection Mw6.5-6.7 Mw6.5 0-10 km 0 km Mw6.8-7.2 Mw7.0 11-30 km 20 km Mw7.3-7.7 Mw7.5 31-50 km 40 km Mw7.8-8.2 Mw8.0 51-70 km 60 km Mw8.3-8.5 Mw8.5 >70 km and <100 km 60 km Page 43 of 110 4.9.2 Interpolation Method Interpolation method is the computation of points or values between ones that are known or tabulated using the surrounding points or values (http://mathworld.wolfram.com). Input data is recently determined hypocenter parameters such as longitude, latitude, depth and magnitude. Each four corners of the data point consist of values of longitude, latitude, depth and two magnitudes. Our definition of data point is consists of tsunami heights and arrival times. The data point at each nearest corner with determined hypocenter is retrieved from database. If the data point consists variant of magnitude and depth, the recently determined hypocenter is computed by using horizontal and vertical interpolation methods based on the nearest eight (8) corners in the surrounding (Figure 34). Magnitude or Depth x 2 Latitude Longitude Data point Interpolated data point Determined Hypocenter Figure 34. The interpolation data point of the determined hypocenter in 3 dimensions view. The horizontal interpolation method of epicenter location is calculated by linear method and considered the nearest 4 corners data point in surrounding the determined hypocenter (Figure 35). Page 44 of 110 Latitude y S4 S3 2 y2 3 2 S 6y S 7 S 1 1 1 y1 S1 1 x1 S2 x2 S 1 0 Longitude Figure 35. Horizontal interpolation method of epicenter location (e.g. Sugeng, 2007 and Chai, 2008) The epicenter location interpolation can be determined by the following equations; x2 x1 S2 Point (1) = S1 x1 x 2 x1 x 2 Point (2) = S 4 x2 x1 S3 x1 x 2 x1 x 2 Point (3) = Point (1) (17) y2 y1 + Point (2) y1 y 2 y1 y 2 Here, points S1, S2, S3 and S4 are the nearest data point surrounding the determined hypocenter, Point (1) is interpolated grid point between S1 and S2, Point (2) is interpolated grid point between S3 and S4, Point (3) is epicenter input of determined hypocenter, y1 and y2 are the distance of lower and upper latitude from epicenter to interpolated point and x1 and x2 are the distance of lower and upper longitude from interpolated point to closest data point. The vertical interpolation method of magnitude and depth are considered the nearest 4 elements, which has nearest distance to the determined hypocenter. Each data point consists of two magnitudes and one depth or equivalent to 8 cases. The coefficients of magnitude (MC) and depth (DC) interpolation are calculated by a logarithm method based on the following equations (Figure 36): Page 45 of 110 (11) 2 1 5 ) DC 1 10 1 10 d1 d d1 d 2 d1 d 2 d1 d 2 , MC 1 10 1 10 m2 m m2 m1 m2 m1 m2 m1 Point (1) = A1 M C A2 (1 M C ) (18) Point (2) = B1 M C B2 (1 M C ) Point (3) = Point (1) DC + Point (2) (1 DC ) Here, point A1, A2, B1 and B2 are the data point consisting of depth and magnitude which has the nearest distance to the determined hypocenter, Point (1) is interpolated grid point between A1 and A2, Point (2) is interpolated grid point between B1 and B2, Point (3) is interpolated grid point of magnitude and depth, d1 and d2 are lower and upper of depth and m1 and m2 are lower and upper of magnitude. d1 m m2 A1 1 A2 d d2 Magnitude m1 2 2 S 6y S 7 1 3 B1 y B2 S 1 0 Depth Figure 36. Vertical interpolation method of magnitude and depth Page 46 of 110 ( 1 6 ) ( 1 7 ) 4.9.3 Extrapolation Method The extrapolation method is performed to determine the non-existing data point at lower and upper magnitude of the determined hypocenter or when there is no surrounding data point (Figure 37). MA M1 M2 MB Magnitude Figure 37. The extrapolation method of magnitude (e.g. Chai, 2008). The coefficients of upper and lower magnitude are described by the following equations: Co U 10 CoL 10 M B M 2 2 log10 0.3 (19) M A M1 2 log10 0.3 Here, Co(U) and Co(L) are corresponding to coefficient values of upper and lower magnitude, MA and MB are the lower and upper magnitude of determined magnitude and M1 and M2 are the lower and upper magnitude of data point which is the closest with determined magnitude. In tsunami database, only the coefficient value of upper magnitude is being taken into account for searching method. However, the coefficient value of lower magnitude is very rarely used in this study by the assumption that an earthquake with a magnitude lower than 6.5 doesn‟t generate a tsunami. In order to get the database output for tsunami heights, we multiply the data point of the nearest element of depth with coefficient value of the upper magnitude (Mw8.5). The tsunami arrival times are selected at the fastest time. Page 47 of 110 ( 1 8 ) 4.9.4 Maximum Risk Method Maximum risk method is used to search the maximum data at each coastal point. The source points of those located within the half length of the earthquake‟s fault distance (Figure 38) and given the maximum data of tsunami at the coastal area will be chosen as database output (e.g. Norhadizah, 2007 and Chai, 2008). The length (L) of the earthquake that is controlled by moment magnitude (Mw) is determined by using the Scaling Law as described in equation (8). This method is easier than that of interpolation one. However, when the magnitude is bigger it will cause the target area for searching to increase exponentially and longer time is needed to get the output of the database. Figure 38. Source points those located within the half length (L/2=111.9 km for Mw8.5) of the earthquake‟s fault distance and given the maximum data at the coastal area are selected as database output. Page 48 of 110 4.10 Earthquake and Tsunami Bulletins Issuance of different types of bulletin for a particular region of the coastal areas can be divided into 4 types (Table 9) and the flow chart for issuing bulletins is described in Figure A-3-1 in Appendix-3. Earthquake Bulletin No. 1 contains earthquake information that is determined from the seismic network and will be issued within less than 15 minutes for magnitude more than Mw5.9. If there is a possibility of tsunami generation, Tsunami Bulletin No. 2 will be issued as soon as the earthquake tsunami potential has been analyzed based on the pre-computed scenarios that is available in the database. The Tsunami Bulletin No. 3 will be issued upon confirmation of water level data from buoys and tide gauges. This bulletin will be updated hourly until there are no significant changes of the water level observed. If there are no significant changes of the water level observed, Tsunami Bulletin No.4 will be issued for termination purpose. Bulletin Type Earthquake Bulletin No. 1 Tsunami Bulletin No. 2 Tsunami Bulletin No. 3 Tsunami Bulletin No. 4 Table 9. Type of bulletins Description of Bulletin Earthquake Information Estimation from pre-computed scenario database Observation water-level data from BPRs and tide gauges Termination of warning Earthquake Bulletin No. 1 issuance generally depends on pre-determined criteria or thresholds (Figure A-3-2 in Appendix-3). This bulletin contains earthquake parameters that can be determined quickly from seismic waveform data such as origin time, coordinates, depth, magnitude, occur on land or sea, region and tsunami evaluation. This bulletin will be issued based on the earthquake strength as shown in Table 10. The moment magnitude or Mwp is more accurate for large earthquakes than the common Richter magnitude (e.g. mb). It is recommended that the moment magnitude to be used for initial Mwp, based on the first arriving seismic P waves. Based on the Tsunami Warning Center Reference Guide, the definitions of tsunami potential are described as per below; Local tsunami: A local tsunami is one with destructive or life threatening effects usually limited to within 100 kilometers (km) of the epicenter. Regional Tsunami: A regional tsunami is one with destructive or life threatening effects usually limited to within 1000 km of the epicenter. Ocean-wide Tsunami: An ocean-wide tsunami is one with destructive or life threatening effects that can extend across an entire ocean basin. Page 49 of 110 Table 10. Product thresholds based on earthquake strength Earthquake Earthquake Earthquake Description of Bulletin Type Depth Location Magnitude tsunami potential Mw or Mwp < 100 km Under or ≥ 7.9 Potential for a Earthquake Bulletin No.1, very near destructive ocean- Tsunami Bulletin No. 2, the sea wide tsunami Tsunami Bulletin No. 3 and Tsunami Bulletin No. 4 7.6 to 7.8 Potential for a Earthquake Bulletin No.1, destructive Tsunami Bulletin No. 2, regional tsunami Tsunami Bulletin No. 3 and Tsunami Bulletin No. 4 7.0 to 7.5 Potential for a Earthquake Bulletin No.1, destructive local Tsunami Bulletin No. 2, tsunami Tsunami Bulletin No. 3 and Tsunami Bulletin No. 4 6.5 to 7.0 Very small Earthquake Bulletin No.1, potential for a Tsunami Bulletin No. 2, destructive local Tsunami Bulletin No. 3 and tsunami Tsunami Bulletin No. 4 6.0 to 6.4 No tsunami Earthquake Bulletin No.1 potential Any depth Inland ≥ 6.5 No tsunami Earthquake Bulletin No.1 potential ≥ 100 km Inland or ≥ 6.5 No tsunami Earthquake Bulletin No.1 sea potential 4.10.1 Warning Category The warning category is based on the premise that residents on the coastal areas which falls within 60 minutes travel time from a tsunamigenic earthquake source need to be warned based on the expected tsunami heights that are retrieved from pre-computed scenarios tsunami database. Those coastal areas which fall outside the 60 minutes travel time from tsunami source should be put under an alert or watch status and will be upgraded to a warning upon confirmation of water level data from buoys and tide gauges. Table 11 is described the warning category to be issue based on travel times and expected tsunami heights at the coastal areas. According to the ICG/IOTWS Working Group 4 recommendations, the common threshold for threat or no threat is 0.5 m at 1 m water depth (IOC, 2009). This threshold is used as guidance for issuing tsunami threat or not threat at the coastal blocks. Page 50 of 110 Table 11. Tsunami warning category (e.g. Srinivasa, K.T, 2009) Scenario Database (Travel Times and Tsunami Heights) Travel Times < 60 minutes Travel Times > 60 minutes Expected Tsunami Bulletin Message Expected Tsunami Bulletin Message Height Height > 2m Warning > 2m Alert 0.5 to 2 m Alert 0.5 to 2 m Watch < 0.5 m Watch < 0.5 m Watch 4.10.2 Design of Earthquake Bulletin No. 1 ############################################################################ MALAYSIAN NATIONAL TSUNAMI EARLY WARNING CENTRE (MNTEWC) Malaysian Meteorological Department Jalan Sultan, 46667, Petaling Jaya, Selangor, Malaysia Tel:(+6-03)79550470, Fax:(+6-03)79584824/79550482 E-mail:[email protected],Website:http://www.met.gov.my ############################################################################ Earthquake Bulletin Number : 1 Issued at : DDD, DD MMM YYYY, HH:MM:SS UTC The MNTEWC has detected an earthquake with the following preliminary parameters : Origin Time : DD MMM YYYY, HH:MM:SS UTC Coordinates : xx.x (N or S) xxx.x (E or W) Depth (km) : xx Magnitude : x.x Land/Sea : xxxx Location : xxxxxxxxx Remark : xxx km xxxxxxxxx of xxxxxx, xxxxxxx Tsunami Evaluation : There is xxxxxxxxxxxx. This will be the only bulletin for this event unless additional information becomes available. Time of received by Tsunami Warning Focal Point (Feedback for evaluation) : Any inquiry addressed to [email protected] Page 51 of 110 4.10.3 Design of Tsunami Bulletin No. 2 ############################################################################ MALAYSIAN NATIONAL TSUNAMI EARLY WARNING CENTRE (MNTEWC) Malaysian Meteorological Department Jalan Sultan, 46667, Petaling Jaya, Selangor, Malaysia Tel:(+6-03)79550470, Fax:(+6-03)79584824/79550482 E-mail:[email protected],Website:http://www.met.gov.my ############################################################################ Tsunami Bulletin Number : 2 Issued at : DDD, DD MMM YYYY, HH:MM:SS UTC This bulletin applied to areas within the Indian Ocean Region TSUNAMI INFORMATION The MNTEWC has detected an earthquake with the following revised parameters: Origin Time : DD MMM YYYY, HH:MM:SS UTC Coordinates : xx.x (N or S) xxx.x (E or W) Depth (km) : xx Magnitude : x.x Land/Sea : xxxx Location : xxxxxxxxx Remark : xxx km xxxxxxxxx of xxxxxx, xxxxxxx Estimated Tsunami Arrival Time and Tsunami Wave Amplitude TSUNAMI WARNING Coastal Location xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx Country xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx Min MM MM MM MM MM MM Arrive Time (UTC) Amplitude Time Date (m) HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x Page 52 of 110 TSUNAMI ALERT Coastal Location xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx Country xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx Min MM MM MM MM MM MM MM MM MM MM MM MM MM MM Arrive Time (UTC) Amplitude Time Date (m) HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x Min MM MM MM MM MM MM MM MM MM MM MM MM MM MM MM Arrive Time (UTC) Amplitude Time Date (m) HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x HH:MM:SS DD-MMM-YYYY x.x TSUNAMI WATCH Coastal Location xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx Country xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx xxxxxx This will be the final bulletin issued unless there are potential of tsunami generation changes by re-evaluation of the earthquake parameters. Page 53 of 110 4.10.4 Design of Tsunami Bulletin No. 3 (Upgrade or Downgrade) ############################################################################ MALAYSIAN NATIONAL TSUNAMI EARLY WARNING CENTRE (MNTEWC) Malaysian Meteorological Department Jalan Sultan, 46667, Petaling Jaya, Selangor, Malaysia Tel:(+6-03)79550470, Fax:(+6-03)79584824/79550482 E-mail:[email protected],Website:http://www.met.gov.my ############################################################################ Tsunami Bulletin Number : 3 Issued at : DDD, DD MMM YYYY, HH:MM:SS UTC TSUNAMI INFORMATION The MNTEWC has detected an earthquake with the following revised parameters: Origin Time : DD MMM YYYY, HH:MM:SS UTC Coordinates : xx.x (N or S) xxx.x (E or W) Depth (km) : xx Magnitude : x.x Land/Sea : xxxx Location : xxxxxxxxx Remark : xxx km xxxxxxxxx of xxxxxx, xxxxxxx TSUNAMI OBSERVATION REPORT Measurement or Report of Tsunami Observations from Buoy and Tide Gauge Stations. Tide Gauge/Buoy Lon Lat xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxx xxx xxx xxx xxx xxx xxx xxx Arrival Time (UTC) Amplitude Min Time Date (m) MM HH:MM:SS DD-MMM-YYYY x.x MM HH:MM:SS DD-MMM-YYYY x.x MM HH:MM:SS DD-MMM-YYYY x.x MM HH:MM:SS DD-MMM-YYYY x.x Bulletin will be issued hourly or sooner if conditions warrant. The tsunami warning will remain in effect until further notice. Page 54 of 110 4.10.5 Design of Tsunami Bulletin No. 4 (Cancellation of Warning) ############################################################################ MALAYSIAN NATIONAL TSUNAMI EARLY WARNING CENTRE (MNTEWC) Malaysian Meteorological Department Jalan Sultan, 46667, Petaling Jaya, Selangor, Malaysia Tel:(+6-03)79550470, Fax:(+6-03)79584824/79550482 E-mail:[email protected],Website:http://www.met.gov.my ############################################################################ Tsunami Bulletin Number : 4 Issued at : DDD, DD MMM YYYY, HH:MM:SS UTC TSUNAMI INFORMATION The MNTEWC has detected an earthquake with the following revised parameters: Origin Time : DD MMM YYYY, HH:MM:SS UTC Coordinates : xx.x (N or S) xxx.x (E or W) Depth (km) : xx Magnitude : x.x Land/Sea : xxxx Location : xxxxxxxxx Remark : xxx km xxxxxxxxx of xxxxxx, xxxxxxx TSUNAMI OBSERVATION REPORT Measurement or Report of Tsunami Observations from Buoy and Tide Gauge Stations. Tide Gauge/Buoy Lon Lat xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxx xxx xxx xxx Arrival Time (UTC) Amplitude Min Time Date (m) MM HH:MM:SS DD-MMM-YYYY x.x MM HH:MM:SS DD-MMM-YYYY x.x TSUNAMI WARNING CANCELLATION The tsunami warning issued by MNTEWC is NOW CANCELLED for xxxxxxxxxxxxx xxxxxxxxxxxxx This will be the final bulletin issued for this event unless additional information becomes available. Page 55 of 110 5. RESULTS AND DISCUSSION 5.1 Tsunami Heights The tsunami heights at the coastal points which are obtained by the numerical model are checked at different magnitudes, depths and sources. To check the numerical simulation results, we compared the tsunami heights at the selected coastal points with different magnitudes (M w6.5, 7.0, 7.5, 8.0 and 8.5) and fixed depth (0 km). Therefore, comparison tsunami heights also made with different depths (0, 20, 40 and 60 km) and fixed magnitude (Mw8.0). As well as magnitude and depth, the tsunami heights at the coastal points are also checked with different source points. 5.1.1 Different Magnitudes at Fixed Depth. As magnitude is getting larger, the tsunami heights at the selected coastal points also gets higher as shown in Figure 39 and Table A-4-1 in Appendix-4. Basically, tsunami heights are depending on the uplift of the ocean bottom due to slip dislocation. Based on the Scaling Law (Tatehata, 1997), these implied that the Mw8.5 (7.079 m) produces slip amount 10 times larger than M w6.5 (0.708 m) does. For example, tsunami height at North Andaman coastal point is much larger at Mw8.5 (9.61 m) than Mw6.5 (0.12 m) does. Figure 39. Tsunami heights at the selected coastal points by different magnitudes. Page 56 of 110 5.1.2 Different Depths at Fixed Magnitude. We analyzed the source point named as S15_D by selecting the magnitude of Mw8.0 with various depths (0, 20, 40 and 60 km). As well as magnitude, the tsunami heights at the output points are shown slightly higher at the shallow source (e.g. 0 km) than at the deeper source (e.g. 60 km) (Figure 40 and Table A-4-2 in Appendix-4). Theoretically, the shallow source is able to generate the uplift of ocean bottom higher than deeper source, and these results are totally agreeable with the theory. This figure has shown that the trend line patterns are almost similar at all the coastal points. Basically, the depth of top left corner for Mw8.0 at depth of 20 km is negative, so we forced to 10 km considering that tsunami source must be located at or beneath ocean bottom but not in upper part of ocean bottom. The reason to force the depth of top left corner to 10 km is to avoid instability occurs in numerical simulation model. Since the fault parameters for Mw8.0 at depths 0 and 20 km are the same, the tsunami heights at the coastal points are also similar. Figure 40. Tsunami heights at selected coastal points by different depths. Page 57 of 110 5.1.3 Different Source Points. We analyzed the source points of S15_A, S15_D, S18_A and S18_D by selecting only the magnitude Mw8.0 and depth 0 km, and the results are shown in Figure 41 and Table A-4-3 in Appendix-4. This figure has shown that the tsunami heights at the coastal points are not well defined. There is no relationship between tsunami height at the coastal points and distance of the sources. For example coastal point of North Andaman is located at 202.3 and 120.5 km, and the tsunami height is 0.85 and 0.78 m for S18_A and S18_D, respectively (Table 12). However, each source has shown different behaviour of tsunami heights at the coastal points and this means that the source points also play important roles in estimating the tsunami heights at the coastal points. Figure 41. Tsunami heights at selected coastal points by different sources. Table 12. Distance of coastal points from source points (Chris, 2009) Coastal Point S15_A S15_D S18_A S18_D North Andaman 168.5 km 46.33 km 202.3 km 120.5 km Page 58 of 110 5.2 Tsunami Travel Times The tsunami travel times at the coastal points are obtained by the TTT software is checked by different magnitudes, depths and sources. To check the numerical simulation results, we compared the tsunami travel times at the selected coastal points with different magnitudes (Mw6.5, 7.0, 7.5, 8.0 and 8.5) at the fixed depth (0 km). Therefore, comparison travel times also made with different depths (0, 20, 40 and 60 km) at the fixed magnitude (Mw8.0). As well as magnitude and depth, the tsunami travel times are also being checked by different sources. 5.2.1 Different Magnitudes at Fixed Depth. The tsunami travel times for source point namely as S15_D is analyzed at the different magnitudes (Mw6.5, 7.0, 7.5, 8.0 and 8.5). There are not many differences in tsunami travel times at the coastal points with difference magnitudes are observed (Figure 42 and Table A-4-4 in Appendix-4). However, the tsunami travel times at Mw8.5 are slightly faster than Mw6.5 does at most of the coastal points. The inverse tsunami travel times which are obtained by TTT software depend on the distance between the coastal point and grid points of the deformation area as described in Table 6. For Mw8.5, the deformation area is wider than at Mw6.5. Therefore, the distance between grid points of deformation area and coastal points is closer for Mw8.5 than Mw6.5, and the tsunami travel times for Mw8.5 is faster than for Mw6.5. Figure 42. Tsunami travel times at selected coastal points by different magnitudes. Page 59 of 110 5.2.2 Different Depths at Fixed Magnitude. We analyzed the tsunami travel times at different depths (0, 20, 40 and 60 km) within the same magnitude (Mw8.0) as shown in Figure 43 and Table A-4-5 in Appendix-4. The trend line patterns of tsunami travel times are almost similar at all the coastal points. As well as magnitude, the tsunami travel times at different depths are not much difference in arrival times which are observed at all the coastal points. This implied that an earthquake depth with the same magnitude gives a small variation in travel times. Figure 43. Tsunami travel times at selected coastal points by different depths. Page 60 of 110 5.2.3 Different Source Points. We analyzed the source points of S15_A, S15_D, S18_A and S18_D by selecting only the magnitude of Mw8.0 and depth 0 km, and the results are shown in Figure 44 and Table A-4-6 in Appendix-4. The trend line patterns of tsunami travel times are almost agreeable to each other at all the coastal points. However, the tsunami travel times depend on the distance between sources and outpoint points. The nearest distance has shown faster travel times and later in far distance (Table 13). For example coastal point of North Andaman is located 46.33 and 202.3 km away, and tsunami travel time is 00.0 and 73.8 min from the source points of S15_D and S18_A, respectively. Figure 44. Tsunami travel times at selected coastal points by different sources. Table 13. Distances of North Andaman from sources and tsunami travel times Source Point Distance (km) TTT (min) S15_D 46.33 00.0 S18_D 120.5 53.9 S15_A 168.5 64.6 S18_A 202.3 73.8 Page 61 of 110 5.2.4 Comparison of Tsunami Arrival Times between TTT and Simulation Result. The comparison of tsunami arrival times between TTT and numerical simulation results for S15_D (Mw8.0 and 0 km) is shown in Figure 45 and Table A-4-7 in Appendix-4. This figure shows that the tsunami arrival times that was estimated by numerical simulation (red line) has similar agreement with TTT (cyan line) in all the coastal points. The tsunami arrival time which is obtained directly from the numerical simulation is slightly faster than TTT. Thus, tsunami arrival times in the numerical simulation are calculated from the beginning of most edges of deformation area to the coastal points. However, in TTT, the tsunami arrival times are inversely calculated from coastal points to the grid points of deformation area, which has absolute value more than 0.05 m. Therefore, the tsunami propagation over the distance between TTT and numerical simulation lends a time difference of tsunami arrival at the coastal points. The time difference refers to the propagation of tsunami between the grid points of deformation area, which has an absolute value of more than 0.05 m and most edges of the deformation area. Since the tsunami arrival times calculated by TTT are in good agreement with those obtained from numerical simulation, TTT method can be applied to estimate the tsunami arrival times at the coastal area (e.g. Netai, 2007). Simulation Figure 45. Tsunami arrival times at selected coastal points were obtained directly from numerical simulation and TTT software. Page 62 of 110 5.3 Application of Green’s Law The comparison of tsunami heights for source point (S15_D) at the coastal points are obtained directly from numerical simulation and application of Green‟s Law at forecast point of 50 m bathymetric contour depth as shown in Figure 46 and Table A-4-8 in Appendix-4. This figure shows that the tsunami heights at the coastal points with application of Green‟s Law (cyan line) has higher value compared to the results which are obtained directly from numerical simulation (red line) at most of the coastal points, especially for the coastal points that located close to the source point. Green‟s Law application has been validated in subsection of 5.4.1, and gave the reliable tsunami heights at the coastal points. Therefore, the tsunami heights results which are obtained directly by the numerical simulation are not appropriate for tsunami warning. If the tsunami heights which are obtained directly from numerical simulation are being taken into consideration for tsunami warning, the arrival of tsunami at the coastal points will be underestimated. It‟s most applicable to use tsunami heights with application of Green‟s Law. The 5 arc-minute of bathymetry data is not reliable for estimating the tsunami heights at the coastal points. The finer bathymetry data may be needed to calculate the tsunami heights near the coastal areas. Figure 46. Tsunami heights at selected coastal points were obtained directly from numerical simulation and application of Green‟s Law. Page 63 of 110 5.4 Validation Models 5.4.1 TUNAMI-F1 in Spherical Coordinates System Numerical model of TUNAMI-F1 is validated against Bengkulu Tsunami on 12 September 2007 in terms of tsunami heights and tsunami arrival times. The maximum heights of simulated tsunami indicate that the tsunami energy is concentrated to directions perpendicular to the strike of fault (Figure 47). The maximum heights areas are concentrated in vicinity to epicenter (blue star) and southwest coastlines of Southern Sumatra, Indonesia. The tsunami propagation snapshots over the region are shown in Figure A-5-1 in Appendix-5. Figure 47. Maximum tsunami heights of the Bengkulu Tsunami (Left). Tsunami waveforms at Padang tide gauge station at 1 and 50 m water depth (Right). According to the PTWC, the arrival time of tsunami at Padang tide gauge station is 43 min (11:54 UTC 12 September 2007). The tsunami travel time which was calculated by the numerical simulation and TTT method are 39 min (11:50 UTC 12 September 2007) and 42 min (11:53 UTC 12 September 2007), respectively. The inverse tsunami travel times are calculated from coastal point (Padang) to the grid points of deformation area which has absolutely more than 0.05 m (Figure 48). These reading were approximated with the observed one. Due to low resolution of 2 arc-minute bathymetry data, the tsunami heights at the coastal point are unreliable compared with observed one. Tsunami heights at the coastal point which were directly obtained from the numerical simulation are underestimated. Thus, to get the Page 64 of 110 reliable tsunami heights at the coastal point, Green‟s Law calculation is then applied. Application of Green‟s Law has shown that the tsunami height at Padang tide gauge station is in the acceptable value compared with the observed one (Table 14). Figure 48. Inverse refraction diagram by TTT method from coastal point (Padang) to the deformation area of tsunami source. The contour interval of tsunami travel times and deformation area are 10 min and 0.1 m, respectively. Table 14. Comparison of tsunami heights and arrival times at Padang tide gauge station. PTWC (1 m) Padang (50 m) Padang (1 m) Arrival Wave Arrival Wave Wave Arrival Wave Time Height Time Height Height Time Height (min) (m) (min) (50m) GL (1m) (min) (1m) 70 0.35 70 0.14 m 0.37 m 80 0.38 m 115 0.56 112 0.25 m 0.67 m 119 0.34 m 157 0.98 161 0.31 m 0.83 m 160 0.43 m Page 65 of 110 5.4.2 NAMI-DANCE in Spherical Coordinates System The numerical model of NAMI-DANCE version 4.7 has shown that the maximum tsunami heights areas are concentrated in vicinity to epicenter and southwest coastlines of Southern Sumatra, Indonesia (Figure 49). Tsunami propagation snapshots are shown in Figure A-5-2 in Appendix-5. Padang Sumatra Figure 49. Maximum tsunami heights of the Bengkulu Tsunami (Left). Tsunami waveforms at Padang tide gauge station at 1 and 50 m water depth (Right). The time arrival of tsunami at Padang tide gauge station is 40 min (11:51 UTC 12 September 2007) that is faster by 3 min compared with the observed one. However, in TTT method the tsunami arrival time at Padang tide gauge station is 72 min (12:23 UTC 12 September 2007) that is 29 min later. The difference is due to the TTT method which calculated inverse travel time from coastal point to the center of fault or epicentre (Figure 50). Application of Green‟s Law has shown that the tsunami heights at coastal point are overestimated compared with the observed one (Table 15). However, tsunami height which obtained directly from simulation at 1 m looks more reliable than application of Green‟s Law. Table 15. Comparison of tsunami heights and arrival times at Padang tide gauge station. PTWC (1 m) Padang (50 m) Padang (1 m) Arrival Wave Arrival Wave Wave Arrival Wave Time Height Time Height Height Time Height (min) (m) (min) (50m) GL (1m) (min) (1m) 70 0.35 83 0.06 m 0.17 m 79 0.38 m 115 0.56 115 0.51 m 1.42 m 109 0.68 m 157 0.98 171 0.65 m 1.81 m 164 0.41 m Page 66 of 110 Current version of NAMI-DANCE is still under probation period, and we expected the latest version 4.8 or more will be able to validate against the Bengkulu Tsunami. Figure 50. Inverse refraction diagram by TTT method from coastal point (Padang) to the center of fault (green star) of tsunami source. The contour interval of tsunami travel times is 10 min. 5.4.3 TUNAMI-N2 in Cartesian Coordinate System Numerical model of TUNAMI-N2 in Cartesian coordinate system also is also validated against Bengkulu Tsunami on 12 September 2007. The maximum heights of simulated tsunami indicate that the tsunami energy is concentrated to directions perpendicular to the strike of fault (Figure 51). Tsunami propagation snapshots over the region are shown in Figure A-5-3 in Appendix-5. The maximum heights areas are concentrated in vicinity to epicenter (green star) and southwest coastlines of Southern Sumatra, Indonesia. According to the PTWC, the arrival time of tsunami at Padang tide gauge station is 43 min (11:54 UTC 12 September 2007). In numerical simulation and TTT calculations the time arrival of tsunami are 40 min (11:51 UTC 12 Page 67 of 110 September 2007) and 43 min (11:54 UTC 12 September 2007), respectively. These reading were approximately with the observed one. The use of 1 arc-minute bathymetry data to estimate the tsunami heights at coastal point is unreliable compared with observation. Tsunami heights which were directly obtained from numerical simulation at the coastal point are underestimated. Thus, the application of Green‟s Law is then applied to the tsunami height at forecast point (50 m) to estimate the reliable tsunami heights (1 m). Application of Green‟s Law has shown that tsunami heights at the Padang tide gauge station are in the range of acceptable value compared with the observed one (Table 16). Figure 51. Maximum tsunami heights of the Bengkulu Tsunami (Left). Tsunami waveforms at Padang tide gauge station at 1 and 50 m water depth (Right). Table 16. Comparison of tsunami heights and arrival times at Padang tide gauge station. PTWC (1 m) Padang (50 m) Padang (1 m) Arrival Wave Arrival Wave Wave Arrival Wave Time Height Time Height Height Time Height (min) (m) (min) (50m) GL (1m) (min) (1m) 70 0.35 75 0.11 m 0.30 m 88 0.29 m 115 0.56 112 0.21 m 0.56 m 128 0.42 m 157 0.98 161 0.23 m 0.61 m 171 0.48 m Page 68 of 110 5.4.4 NAMI-DANCE in Cartesian Coordinate System The numerical model of NAMI-DANCE version 4.7 in Cartesian coordinate system has shown that the maximum tsunami heights areas are concentrated in vicinity to epicenter and southwest coastlines of Southern Sumatra, Indonesia (Figure 52). The tsunami propagation snapshots over the region are shown in Figure A-5-4 in Appendix-5. The time arrival of tsunami at Padang tide gauge station is 40 min (11:51 UTC 12 September 2007) that is faster by 3 min compared with the observation. However, in TTT the tsunami arrival time at Padang tide gauge station is 72 min (12:23 UTC 12 September 2007). The difference is due to the TTT method which was calculating inverse travel time from coastal point to the center of fault or epicentre. Application of Green‟s Law has shown that tsunami heights at coastal point are overestimated compared with the observed one (Table 17). However, tsunami heights which are obtained directly from the numerical simulation at 1 m looks more reliable than application of Green‟s Law. Figure 52. Maximum tsunami heights of the Bengkulu Tsunami (Left). Tsunami waveforms at Padang tide gauge station at 1 and 50 m water depth (Right). Table 17. Comparison of tsunami heights and arrival times at Padang tide gauge station. PTWC (1 m) Padang (50 m) Padang (1 m) Arrival Wave Arrival Wave Wave Arrival Wave Time Height Time Height Height Time Height (min) (m) (min) (50m) GL (1m) (min) (1m) 70 0.35 83 0.07 m 0.07 m 78 0.37 m 115 0.56 115 0.53 m 1.46 m 109 0.69 m 157 0.98 170 0.66 m 1.82 m 164 0.44 m Page 69 of 110 5.4.5 Comparison Waveforms at the Outpoint Points Firstly, we compared the tsunami heights at 50 m water depth (left hand side of Figure 53) which estimated by NAMI-DANCE 4.7 is slightly higher compared with other models at most of the time. Waveform that is calculated by TUNAMI-N2 (green line) was slightly lower than TUNAMI-F1 (blue line) because in the shallow water equations, the bottom friction effect and non-linear term are taken into consideration. These terms might cause the waveform to become slightly lower and delayed in arrival when compared with linear term. For 1 m water depth (right hand side of Figure 53), the waveform that is calculated by NAMI-DANCE 4.7 is slightly higher than other waveforms, and the first arrival of tsunami at Padang tide gauge station was uplifted. However, the other models had shown that the first arrival of tsunami at the Padang tide gauge station is subsidence, and this result also agreed with the one observed at the tide gauges. Since the NAMI-DANCE version 4.7 cannot validate against the real tsunami event, perhaps the final version of NAMI-DANCE version 5.0 (Multiple Nested Grid System) which will be available in May 2010, and had been tested with real tsunami events, can validate the event. The waveforms of those calculated by NAMI-DANCE 4.7 in spherical and Cartesian coordinate systems using non-linear term equations are similar most of the time. The propagation of tsunamis in small region will neglect the effect of earth spherical. This implied that for near field tsunamis which are calculated by NAMI-DANCE 4.7, the waveform patterns are similar both in spherical and Cartesian coordinate systems. Figure 53. Comparison tsunami waveforms at 1 and 50 m water depth using TUNAMIF1 (blue line), TUNAMI-N2 (green line), NAMI-DANCE Version 4.7 in spherical coordinates system (red line) and NAMI-DANCE Version 4.7 in Cartesian coordinate system (amber line). Page 70 of 110 5.5 Tsunami Database The database outpoint can be retrieved from the data points by simple, interpolation, extrapolation and maximum risk methods. In this study, we assumed that the real case scenario of the determined hypocenter has earthquake parameters as described in Table 18. Figure 54 has shown the epicenter location of the determined hypocenter (red star) in Northern Sumatra, Indonesia, which is surrounded by the available data points. Table 18. Assumption of the earthquake parameters Parameters Value Origin Time 2300Z (12 Jul 2009) Longitude, Latitude 93.30E, 4.30N Magnitude (Mw) 8.3 Depth (km) 50 Figure 54. Epicenter location (red star) of the determined hypocenter. Page 71 of 110 5.5.1 Simple Method The tsunami heights and tsunami arrival times at the coastal area can be retrieved from tsunami database by performing simple method. This method seeks data point of those located in the nearest horizontal distance from the determined hypocenter. Therefore, the nearest elements of magnitude and depth of the determined hypocenter are then selected from the closest data point as database output. According to Figure 54, the nearest data point with the determined hypocenter is S34_E. This data point is located 31.44 km away from the determined hypocenter. For database output, the nearest elements of magnitude and depth of data point with the determined hypocenter are Mw8.5 and 40 km, respectively. 5.5.2 Interpolation Method For interpolation method, the nearest 4 corners data point surrounding the determined hypocenter in horizontal distance is calculated. The nearest 4 corners data points are S34_D, S34_E, S35_D and S35_E. Thus, the vertical elements of the depth are 40 and 60 km and combining with Mw8.0 and 8.5. Each of the 8 corners data point consists of 2 scenarios (e.g. M w8.0 and 8.5 at depth 40 km) and 16 scenarios in total. The coefficients value of magnitude and depth are 0.168 and 0.240, respectively. Each data point is calculated by vertical interpolation of magnitudes and depths and lastly with horizontal interpolation for epicenter location. 5.5.3 Extrapolation Method The results for magnitude of Mw8.3 can be determined by simple and interpolation methods. However, in this study, we would like to compare the results obtained with other methods. At first, we search the nearest data points surrounding the determined hypocenter and apply simple method. Tsunami arrival times are then selected at the nearest elements of magnitude and depth. The nearest element with similar depth is as described in Table 16. Therefore, tsunami heights at Mw8.3 are estimated by multiplication of coefficient value (Co(U) =2.0) with tsunami heights at Mw8.0. This means that database output is twice than that of the Mw8.0. On the other hand, if the magnitude is added 0.3, tsunami heights will be twice. 5.5.4 Maximum Risk Method To search the maximum risks data at each coastal point among the source points, the half length of the fault is 88.9 km and was determined by Scaling Law. Thus, the source points of those located within 88.9 km from the determined hypocenter are S33_D, S33_E, S34_D, S34_E, S34_F, S35_D, S35_E, and S35_F (Figure 55). To avoid denser calculations in tsunami database, each data point is determined by simple method. The combinations of maximum risk of tsunami at the coastal area are selected as database output. Thus, tsunami heights and arrival times are chosen at the maximum height and faster arrival, respectively. Page 72 of 110 Figure 55. Source points of those located within the half length (88.9 km) of the earthquake‟s fault distance. 5.6 Comparison of Database Output We compared the database outputs of TUNAMI-F1 numerical model by using different searching methods as mentioned in subsections 5.5.1 to 5.5.4 items of tsunami heights and tsunami arrival times. We assumed that the determined hypocenter has earthquake parameters as described in Table 16. Page 73 of 110 5.6.1 Tsunami Heights We analyze and compare the tsunami heights using different searching methods as shown in Figure 56 and Figure A-6-1 in Appendix-6. This figure has shown that the trend lines pattern almost well recognised at all the coastal points. The extrapolation method showed that the database outputs are slightly lower than other searching methods but still in the range of acceptable values. Thus, extrapolation method can be used to estimate the outputs for magnitude of more than Mw8.5. Basically, interpolation results should be slightly lower than simple method because in database the outputs are chosen at Mw8.5 and Mw8.3 in simple and interpolation methods, respectively. Maximum Risk method results have shown the highest among the others because this method searches the maximum possible impact of tsunami at the coastal area within the half length of the earthquake fault in distance. Figure 56. Database outputs of tsunami heights using different searching methods Page 74 of 110 5.6.2 Tsunami Arrival Times We analyze and compare the tsunami arrival times using different searching methods as shown in Figure 57 and Figure A-6-2 in Appendix-6. This figure has shown that the trend lines pattern almost well fit at all the coastal points. However, there is a slight difference in time arrival of tsunami at the coastal points. Tsunami arrival times of those obtained by simple and extrapolation are the same because they are chosen at the same element of data point. On the other hand, the time arrival of tsunami which is obtained by interpolation method is slightly later than other searching methods. In maximum risk method, it has been shown that the arrival time of tsunami was slightly faster because this method searches the possible minimum time travel within the half length of the earthquake fault in distance. Figure 57. Database outputs of tsunami arrival times using different searching methods Page 75 of 110 5.7 Application of Searching Methods To minimize time consumption due to searching available data points in tsunami database for database outputs, we applied the retrieve method based on distance from the available data points (Figure 58). If the distance of the determined hypocenter is less than 15.7 km in radius from the nearest data point, then simple method is applied. Otherwise, interpolation method is then applied if the distance is more than 15.7 km from the nearest data point. The extrapolation method will be applied if the determined hypocenter with magnitude more than 8.5 or no data point in surrounding is available. However, simple method must be applied first to search the nearest element of depth parameter before applying extrapolation method to get the database output. Latitude S4 S3 S1 S2 S 6 S 7 15.7 km S 1 0 Longitude Simple method Interpolation method Figure 58. Areas selection for searching methods in tsunami database. Page 76 of 110 5.8 Web Application for Tsunami Database Tsunami databases are retrieved by combination of PHP scripting language and SQL command syntax. PHP scripting language chooses the most appropriate data point from database which matches the real earthquake parameters. The appropriate data point from database is retrieved by simple, interpolation or extrapolation methods as mentioned in Figure A-7-1 in Appendix-7. These combinations also generate earthquake and tsunami bulletins. For security purposes, only authorized users are allowed to log in into the Integrated Database Management System (Figure A-7-2 in Appendix-7). Successful users then need to enter the fault parameters which are determined by the processing system such as origin time, latitude, longitude, magnitude and depth. These parameters are required as input data (Figure 59). The “Search” button will then automatically select the nearest elements of the real earthquake as database output. Figure 59. Web base interface of tsunami database. Page 77 of 110 5.9 Scenario Case We assumed that the determined hypocenter has earthquake parameters as described in Table 18. For earthquake with magnitude more than 6.4, Earthquake Bulletin No. 1 will be issued within 15 minutes from the earthquake origin time. These parameters are determined by Antelope, SeisComp3 or Early Bird processing systems, and required as input data into Integrated Database Management System. In the web application tsunami database is then automatically searching the best method to generate Tsunami Bulletin No. 2. 5.9.1 Earthquake Bulletin No. 1 This is the example of the Earthquake Bulletin No. 1 will be issued within 15 minutes from the earthquake origin time by the MNTEWC. ############################################################################ MALAYSIAN NATIONAL TSUNAMI EARLY WARNING CENTRE (MNTEWC) Malaysian Meteorological Department Jalan Sultan, 46667, Petaling Jaya, Selangor, Malaysia Tel:(+6-03)79550470, Fax:(+6-03)79584824/79550482 E-mail:[email protected],Website:http://www.met.gov.my ############################################################################ Earthquake Bulletin Number : 1 Issued at : Sun, 12 Jul 2009, 23:10:00 UTC The MNTEWC has detected an earthquake with the following preliminary parameters : Origin Time : 12 July 2009, 23:00:00 UTC Coordinates : 4.3N 93.3E Depth (km) : 50 Magnitude : 8.3 Land/Sea : Sea Location : Northern Sumatra Remark : 259 km southwest of Banda Acheh, Indonesia Tsunami Evaluation : There is potential for ocean wide tsunami This will be the only bulletin for this event unless additional information becomes available. Time of received by Tsunami Warning Focal Point (Feedback for evaluation) : Any inquiry addressed to [email protected] Page 78 of 110 5.9.2 Tsunami Bulletin No. 2 This is the example of the Tsunami Bulletin No. 2 will be issued within 30 minutes from the earthquake origin time by the MNTEWC. ############################################################################ MALAYSIAN NATIONAL TSUNAMI EARLY WARNING CENTRE (MNTEWC) Malaysian Meteorological Department Jalan Sultan, 46667, Petaling Jaya, Selangor, Malaysia Tel:(+6-03)79550470, Fax:(+6-03)79584824/79550482 E-mail:[email protected],Website:http://www.met.gov.my ############################################################################ Tsunami Bulletin Number : 2 Issued at : Sun, 12 Jul 2009, 23:20:00 UTC This bulletin applied to areas within the Indian Ocean Region TSUNAMI INFORMATION The MNTEWC has detected an earthquake with the following revised parameters: Origin Time : 12 July 2009, 23:00:00UTC Coordinates : 4.2N 93.3E Depth (km) : 30 Magnitude : 8.3 Land/Sea : Sea Location : Northern Sumatra Remark : 270 km southwest of Banda Acheh, Indonesia Estimated Tsunami Arrival Time and Tsunami Wave Amplitude TSUNAMI WARNING Coastal Location Banda Acheh Great Nicobar Country Indonesia India Min 36 46 Arrive Time (UTC) Amplitude Time Date (m) 23:55:59 12-07-2009 3.9 00:06:00 13-07-2009 2.7 TSUNAMI ALERT Coastal Location Country Dondra Head Sri Lanka Arrive Time (UTC) Amplitude Min Time Date (m) 125 01:25:01 13-07-2009 2.4 Page 79 of 110 TSUNAMI WATCH Coastal Location Country Little Andaman Port Blair Trincomalee Phuket Padang Colombo North Andaman Bengkulu Chennai Pyinkayaing Gaaf Dhaal Chedura Island Kakinada Ko Phra Thong Datai Bay Langkasuka Trivandrum Cilacap Male Ko Tarutao Bandar Lampung Sittwe Pantai Cenang Bali Pantai Acheh Pasir Panjang Batu Ferringhi Pantai Merdeka Kuah Teluk Kumbar Yan Kota Kuala Muda Belawan Kuala Perlis Tanjung Piandang Mangalore Teluk Senangi Kuala Muda Pantai Remis Mergui India India Sri Lanka Thailand Indonesia Sri Lanka India Indonesia India Myanmar Maldives Myanmar India Thailand Malaysia Malaysia India Indonesia Maldives Thailand Indonesia Myanmar Malaysia Indonesia Malaysia Malaysia Malaysia Malaysia Malaysia Malaysia Malaysia Malaysia Indonesia Malaysia Malaysia India Malaysia Malaysia Malaysia Myanmar Min 75 89 118 121 136 156 158 161 169 174 185 185 186 188 189 197 200 204 207 209 217 219 228 233 236 238 246 246 247 255 263 265 266 272 274 293 299 300 309 313 Arrive Time (UTC) Amplitude Time Date (m) 00:34:59 13-07-2009 1.4 00:49:01 13-07-2009 1.5 01:18:00 13-07-2009 1.3 01:21:00 13-07-2009 1.4 01:36:00 13-07-2009 0.7 01:55:59 13-07-2009 1.1 01:58:01 13-07-2009 1.0 02:01:10 13-07-2009 0.9 02:09:00 13-07-2009 1.8 02:13:59 13-07-2009 0.7 02:25:01 13-07-2009 1.7 02:25:01 13-07-2009 0.8 02:25:59 13-07-2009 1.7 02:28:01 13-07-2009 2.0 02:28:59 13-07-2009 1.1 02:37:01 13-07-2009 0.9 02:40:01 13-07-2009 0.7 02:43:59 13-07-2009 0.4 02:46:59 13-07-2009 1.4 02:49:01 13-07-2009 0.9 02:57:00 13-07-2009 0.4 02:58:59 13-07-2009 0.8 03:07:59 13-07-2009 1.1 03:13:01 13-07-2009 0.3 03:16:01 13-07-2009 0.7 03:18:00 13-07-2009 0.5 03:25:59 13-07-2009 0.6 03:25:59 13-07-2009 0.7 03:27:00 13-07-2009 0.9 03:34:59 13-07-2009 0.7 03:43:01 13-07-2009 0.8 03:45:00 13-07-2009 0.7 03:46:01 13-07-2009 0.7 03:52:01 13-07-2009 1.1 03:54:00 13-07-2009 0.7 04:13:01 13-07-2009 0.5 04:19:01 13-07-2009 1.0 04:19:59 13-07-2009 0.9 04:28:59 13-07-2009 0.7 04:33:00 13-07-2009 0.7 Page 80 of 110 North West Cape Nibong Tebal Cape Inspiratio Pangkor Baleshwar Grand Gaube Perth Augusta Geraldtown Salalah Duqm Cape Leveque Jaffna Kuala Selangor Victoria Muscat Cape Guaro Hobyo Gulf of Kutch Yangon Gwadar Karachi Chittagong Gavater Pulau_Ketam Esperance Antsiranana Al Mukalia Manakara Magadishu Toamasina Bombay Mamoudzou Kismayo Lamu Aden Quiterajo Mahajanga Mombasa Matapatapa Dares Salaam Angoche Toliara Cap Ste Marie Australia Malaysia Australia Malaysia India Mauritius Australia Australia Australia Oman Oman Australia Sri Lanka Malaysia Seychelles Oman Somalia Somalia India Myanmar Pakistan Pakistan Bangladesh Iran Malaysia Australia Madagascar Yemen Madagascar Somalia Madagascar India Moyatte Somalia Kenya Yemen Mozambique Madagascar Kenya Tanzania Tanzania Mozambique Madagascar Madagascar 315 315 335 340 372 385 394 407 411 416 417 421 425 429 431 432 432 433 439 440 443 448 451 452 455 463 464 467 469 470 472 473 490 501 507 513 530 533 534 538 546 548 550 550 04:34:59 04:34:59 04:55:01 05:00:00 05:31:59 05:45:00 05:54:00 06:07:01 06:10:59 06:16:01 06:16:59 06:21:00 06:25:01 06:28:59 06:31:01 06:31:59 06:31:59 06:33:00 06:39:00 06:40:01 06:43:01 06:48:00 06:51:00 06:52:01 06:55:01 07:03:00 07:04:01 07:07:01 07:09:00 07:10:01 07:12:00 07:13:01 07:30:00 07:40:59 07:46:59 07:52:59 08:10:01 08:13:01 08:13:59 08:18:00 08:25:59 08:28:01 08:30:00 08:30:00 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 0.5 0.7 0.6 0.8 0.8 0.6 0.4 0.5 0.6 0.8 0.5 0.4 0.9 0.4 1.1 0.3 0.7 1.1 0.4 0.7 0.5 0.4 0.7 0.6 0.3 0.1 1.2 0.4 0.8 1.3 0.5 0.4 0.5 1.4 0.7 0.2 0.6 0.4 0.8 0.9 0.9 0.7 0.3 0.5 Page 81 of 110 Djibouti Eucla Motel Kingston South Prince Edward Hobart DurbanSouth Quelimane Darwin Port Elizaberth Maputo Beira Cape Town Djibouti Australia Australia South Africa Australia Africa Mozambique Australia South Africa Mozambique Mozambique South Africa 553 621 625 640 645 648 660 680 694 746 748 796 08:33:00 09:40:59 09:45:00 10:00:00 10:04:59 10:07:59 10:19:59 10:40:01 10:54:00 11:46:01 11:48:00 12:36:00 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 13-07-2009 0.2 0.1 0.1 0.5 0.1 0.5 0.3 0.1 0.4 0.5 0.2 0.2 This will be the final bulletin issued unless there are potential of tsunami generation changes by re-evaluation of the earthquake parameters. Page 82 of 110 5.9.3 Tsunami Bulletin No. 3 This is the only example of the Tsunami Bulletin No. 3 which issued with availabilities of data. ############################################################################ MALAYSIAN NATIONAL TSUNAMI EARLY WARNING CENTRE (MNTEWC) Malaysian Meteorological Department Jalan Sultan, 46667, Petaling Jaya, Selangor, Malaysia Tel:(+6-03)79550470, Fax:(+6-03)79584824/79550482 E-mail:[email protected],Website:http://www.met.gov.my ############################################################################ Tsunami Bulletin Number : 3 Issued at : Mon, 13 Jul 2009, 00:00:00UTC TSUNAMI INFORMATION The MNTEWC has detected an earthquake with the following revised parameters: Origin Time : 12 July 2009, 23:00:00UTC Coordinates : 4.2N 93.3E Depth (km) : 30 Magnitude : 8.3 Land/Sea : Sea Location : Northern Sumatra Remark : 270 km southwest of Banda Acheh, Indonesia TSUNAMI OBSERVATION REPORT Measurement or Report of Tsunami Observations from Buoy and Tide Gauge Stations. Tide Gauge/Buoy Dart Indonesia Dart Nicobar Lon Lat Arrival Time (UTC) Min Time Date 91.89E 0.06N 20 23:20:00 12-07-2009 88.54E 8.90N 25 23:25:00 12-07-2009 Amplitude (m) 2.3 2.0 Bulletin will be issued hourly or sooner if conditions warrant. The tsunami warning will remain in effect until further notice. Page 83 of 110 5.9.4 Tsunami Bulletin No. 4 This is the only example of the Tsunami Bulletin No. 4 for cancellation of warning. ############################################################################ MALAYSIAN NATIONAL TSUNAMI EARLY WARNING CENTRE (MNTEWC) Malaysian Meteorological Department Jalan Sultan, 46667, Petaling Jaya, Selangor, Malaysia Tel:(+6-03)79550470, Fax:(+6-03)79584824/79550482 E-mail:[email protected],Website:http://www.met.gov.my ############################################################################ Tsunami Bulletin Number : 4 Issued at : Mon, 13 Jul 2009, 04:00:00UTC TSUNAMI INFORMATION The MNTEWC has detected an earthquake with the following revised parameters: Origin Time : 12 July 2009, 23:00:00UTC Coordinates : 4.2N 93.3E Depth (km) : 30 Magnitude : 8.3 Land/Sea : Sea Location : Northern Sumatra Remark : 270 km southwest of Banda Acheh, Indonesia TSUNAMI OBSERVATION REPORT Measurement or Report of Tsunami Observations from Buoy and Tide Gauge Stations. Tide Gauge/Buoy Dart Indonesia Dart Nicobar Lon Lat Arrival Time (UTC) Min Time Date 91.89E 0.06N 240 03:00:00 13-07-2009 88.54E 8.90N 240 03:00:00 13-07-2009 Amplitude (m) 0.03 0.02 TSUNAMI WARNING CANCELLATION The tsunami warning issued by MNTEWC is NOW CANCELLED for INDONESIA INDIA This will be the final bulletin issued for this event unless additional information becomes available. Page 84 of 110 6. CONCLUSIONS AND RECOMMENDATIONS Numerical simulation results are verified in terms of tsunami heights and tsunami arrival times at the coastal points. Tsunami heights at the coastal points truly depends on the magnitude, depth and distance from sources. As magnitude getting larger, depth shallower and distance with the source closer tsunami heights becomes higher. As well as tsunami heights, tsunami arrival times are faster with higher magnitude and closest in distance with source. However, earthquake depth gives a small variation in travel times. Comparison of tsunami travel times between the TTT and numerical simulation results had shown a similar agreement. Thus, TTT method can be applied to estimate the tsunami arrival times at the coastal area. Green‟s Law application had been validated against Bengkulu Tsunami and gave reliable tsunami heights at the coastal points. Tsunami heights of those obtained directly from numerical simulations are unreliable, and not appropriate for tsunami warning. If tsunami heights obtained directly from numerical simulation are being taken into consideration for tsunami warning, the arrival of tsunami at the coastal points will be underestimated. The 1, 2 and 5 arc-minute of bathymetry data is not reliable for estimating the tsunami heights at the coastal points. Thus, finer bathymetry data is needed to calculate the tsunami heights near the coastal area. Numerical models of TUNAMI-F1 and TUNAMI-N2 have been verified against Bengkulu Tsunami in terms of tsunami heights at the coastal points with Green‟s Law application and tsunami arrival times by TTT method. However, numerical model of NAMIDANCE version 4.7 is unable to validate against the Bengkulu Tsunami. Perhaps the latest version of NAMI-DANCE will give a better approximation. The tsunami databases are constructed using MySQL. This pre-computed tsunami database includes more than 30,000 earthquake scenarios. Tsunami heights and arrival times are retrieved from database by simple, interpolation, extrapolation and maximum risk methods. These methods are performed by combination of PHP scripting language and SQL command syntax to retrieving for issuing tsunami bulletins. If an earthquake occurs with a magnitude of more than 5.9, the Earthquake Bulletin No. 1 will be issued within 15 minutes from the earthquake origin time. For magnitude of more than 6.4, Tsunami Bulletin No. 2 will then be issued as soon as the earthquake tsunami potential has been analyzed based on the pre-computed scenarios tsunami database. Tsunami Bulletin No. 3 will then be issued upon confirmation of water level data from buoys and tide gauges from local or international channels. This bulletin will be updated hourly until there are no significant changes of water level observation data. If there are no significant changes of water level observed, Tsunami Bulletin No.4 will then be issued for termination purpose. The warning category is based on the premise of the coastal areas which falls within 60 minutes travel time from the tsunamigenic earthquake source and the expected wave height is more than 2 m retrieved from pre-computed scenarios tsunami database, need to be put under warning. For expected tsunami height between 0.6 to 1.9 m and less than 0.5 m, the areas could be put under an alert and watch status, respectively. Those coastal areas which fall outside the 60 minutes travel time from tsunami source could be put under an alert or watch status and upgraded to a warning upon confirmation of water level data from buoys and tide gauges. Page 85 of 110 FUTURE PLAN As a part of our study in developing tsunami database at the Malaysian National Tsunami Early Warning Centre, we hope these databases will be able to provide a reliable tsunami warning to the nation and the neighbouring countries. We would like to extend our study in developing tsunami inundation distance and maps for coastal communities along the coastlines to be included in the tsunami database. Apart from that, we would like to put future consideration for other tsunami sources generation such as volcano and submarine landslide. To fully utilize the Malaysian deep ocean buoys and tide gauges, we would like to expand our study in real time tsunami forecasting using data assimilation. ACKNOWLEDGEMENT We would like to express our gratitude to Dr. Yap Kong Seng (Director General of Malaysian Meteorological Department) for helpful discussions, valuable comments, guidance and supports during our study in MMD. Special thanks to Dr. Fujii Yushiro (Researcher of International Institute of Seismology and Earthquake Engineering, Building Research Institute, Tsukuba, Japan), Mr. Zaidi bin Zainal Abidin (Principal Assistant Director of Geophysics and Tsunami Division), Ms. Zaty Aktar binti Mokhtar, Mr. Afiq Zhofri bin Abdul Razak, Ms. Zamuna binti Zainal and Ms. Amzura binti Amran (Assistants Director of Geophysics and Tsunami Division). Lastly, thanks to all MMD staff for kindly sharing experiences and knowledge. Page 86 of 110 APPENDICES Appendix-1 Figure A-1-1. Coastal blocks for Peninsular Malaysia Figure A-1-2. Coastal blocks for Sabah and Sarawak. Page 87 of 110 Appendix-2 Figure A-2-1. Description tables of skema, FP and HYP from database. Page 88 of 110 Appendix-3 Earthquake Seismic Network (Origin Time, Hypocenter, Magnitude) Bulletin No 1 Tsunami Information No -Earthquake information -No tsunami potential Tsunami Information Land/Ocean Yes -Earthquake information Mag > 6.5 Land Ocean Depth < 100 km Yes -Tsunamigenic potential Ocean Scenario Database (Travel Times, Tsunami Height) Travel Times < 60 min Travel Times > 60 min Expected Tsunami Height Bulletin Message Expected Tsunami Height Bulletin Message >2m Warning >2m Alert 0.5 to 2 m Alert 0.5 to 2m Watch < 0.5 m Watch <0.5m Watch Bulletin No 2 Page 89 of 110 Real Time water Observation Tide Gauges Buoys No significant >0.5m >30 mm Yes Yes Confirm tsunami triggering Tsunami Height Bulletin Message Upgrade Status >2m Warning Warning 0.5 to 2m Alert Warning <0.5m Watch Alert Bulletin No 3 No significant changes All Clear No more dangerous waves are expected Bulletin No 4 Figure A-3-1. System operation procedure for issuing earthquake and tsunami bulletins. Page 90 of 110 Figure A-3-2. Procedures for issuing Earthquake Bulletin No. 1 with or without tsunami potential. Page 91 of 110 Appendix-4 Table A-4-1. Tsunami heights of the coastal points at different magnitudes. Source Point Coastal Point Datai Bay Banda Acheh Cape Leveque Chittagong Yangon Phuket Karachi Mahajanga Antsiranana Little Andaman North Andaman Baleshwar Trincomalee Salalah Djibouti Grand Gaube Male Mamoudzou Kismayo Dares Salaam S15_D_M6.5_D0 S15_D_M7.0_D0 S15_D_M7.5_D0 S15_D_M8.0_D0 S15_D_M8.5_D0 0.01 0.01 0.00 0.01 0.02 0.01 0.00 0.00 0.00 0.02 0.12 0.01 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.03 0.00 0.05 0.06 0.03 0.00 0.00 0.01 0.07 0.26 0.07 0.06 0.01 0.00 0.01 0.01 0.00 0.01 0.00 0.07 0.11 0.01 0.20 0.23 0.11 0.01 0.01 0.03 0.26 1.61 0.24 0.17 0.03 0.01 0.03 0.05 0.02 0.04 0.02 0.20 0.35 0.03 0.63 0.77 0.45 0.02 0.03 0.10 0.88 4.69 0.69 0.42 0.08 0.02 0.07 0.11 0.04 0.11 0.08 0.64 0.85 0.12 1.99 3.36 1.02 0.07 0.07 0.19 2.41 9.61 2.88 1.19 0.15 0.08 0.15 0.31 0.12 0.25 0.24 Remarks: For S15_D_M6.5_D0, it corresponds to source point named S15_D with magnitude 6.5 and depth 0 km. Tsunami height in metre (m). Page 92 of 110 Table A-4-2. Tsunami heights of the coastal points at different depths. Coastal Point Datai Bay Banda Acheh Cape Leveque Chittagong Yangon Phuket Karachi Mahajanga Antsiranana Little Andaman North Andaman Baleshwar Trincomalee Salalah Djibouti Grand Gaube Male Mamoudzou Kismayo Dares Salaam Source Point S15_A_M8.0_D0 S15_D_M8.0_D20 S18_A_M8.0_D40 S18_D_M8.0_D60 0.20 0.35 0.03 0.63 0.77 0.45 0.02 0.03 0.10 0.88 4.69 0.69 0.42 0.08 0.02 0.07 0.11 0.04 0.11 0.08 0.20 0.35 0.03 0.63 0.77 0.45 0.02 0.03 0.10 0.88 4.69 0.69 0.42 0.08 0.02 0.07 0.11 0.04 0.11 0.08 0.19 0.33 0.03 0.62 0.77 0.43 0.02 0.03 0.09 0.85 4.50 0.69 0.36 0.07 0.02 0.06 0.10 0.04 0.10 0.08 0.15 0.24 0.02 0.50 0.69 0.31 0.02 0.02 0.06 0.56 3.14 0.66 0.21 0.04 0.02 0.04 0.07 0.02 0.07 0.07 Remarks: For S15_D_M8.0_D0, it corresponds to source point named S15_D with magnitude 8.0 and depth 0 km. Tsunami height in metre (m). Page 93 of 110 Table A-4-3. Tsunami heights of the coastal points at different sources. Coastal Point Datai Bay Banda Acheh Cape Leveque Chittagong Yangon Phuket Karachi Mahajanga Antsiranana Little Andaman North Andaman Baleshwar Trincomalee Salalah Djibouti Grand Gaube Male Mamoudzou Kismayo Dares Salaam S15_A_M8.0_D0 0.16 0.29 0.04 0.84 0.53 0.32 0.04 0.04 0.09 0.85 2.67 1.00 0.83 0.11 0.03 0.13 0.16 0.07 0.17 0.07 Source Point S15_D_M8.0_D0 S18_A_M8.0_D0 0.20 0.14 0.35 0.26 0.03 0.06 0.63 0.52 0.77 0.34 0.45 0.29 0.02 0.04 0.03 0.07 0.10 0.10 0.88 1.86 4.69 0.85 0.69 0.81 0.42 0.80 0.08 0.12 0.02 0.03 0.07 0.16 0.11 0.12 0.04 0.08 0.11 0.13 0.08 0.12 S18_D_M8.0_D0 0.35 0.41 0.02 0.18 0.77 0.74 0.03 0.03 0.08 0.52 0.78 0.30 0.17 0.06 0.02 0.06 0.07 0.04 0.06 0.07 Remarks: For S15_A_M8.0_D0, it corresponds to source point named S15_A with magnitude 8.0 and depth 0 km. Tsunami height in metre (m). Page 94 of 110 Table A-4-4. Tsunami travel times of the coastal points at different magnitudes. Coastal Point Datai Bay Banda Acheh Cape Leveque Chittagong Yangon Phuket Karachi Mahajanga Antsiranana Little Andaman North Andaman Baleshwar Trincomalee Salalah Djibouti Grand Gaube Male Mamoudzou Kismayo Dares Salaam Source Point S15_D_M6.5_D0 S15_D_M7.0_D0 S15_D_M7.5_D0 S15_D_M8.0_D0 S15_D_M8.5_D0 270.8 266.1 246.0 239.6 235.0 135.9 131.3 111.2 104.8 100.3 547.4 540.0 525.8 524.9 521.5 363.8 362.9 358.9 354.0 347.2 393.3 391.3 371.8 363.9 353.9 188.9 184.2 164.1 157.7 153.1 495.0 491.5 486.4 478.7 469.7 605.2 601.6 583.7 581.2 579.4 535.7 532.1 506.8 504.2 509.8 65.1 61.5 56.2 47.9 39.3 59.3 54.3 0.0 0.0 0.0 301.6 300.0 296.3 293.4 289.5 141.8 138.2 133.5 126.2 117.5 463.1 459.5 454.4 446.8 437.8 600.1 596.6 591.5 583.8 574.9 479.5 419.0 387.9 385.1 453.4 256.5 252.9 247.8 240.2 231.2 562.3 558.8 541.6 539.1 536.5 560.9 557.3 552.2 544.5 535.5 606.5 603.0 597.9 590.1 581.1 Remarks: Tsunami travel times in minutes (min). Page 95 of 110 Table A-4-5. Tsunami travel times of the coastal points at different depths. Coastal Point Datai Bay Banda Acheh Cape Leveque Chittagong Yangon Phuket Karachi Mahajanga Antsiranana Little Andaman North Andaman Baleshwar Trincomalee Salalah Djibouti Grand Gaube Male Mamoudzou Kismayo Dares Salaam Source Point S15_A_M8.0_D0 S15_D_M8.0_D20 S18_A_M8.0_D40 S18_D_M8.0_D60 239.6 104.8 524.9 354.0 363.9 157.7 478.7 581.2 504.2 47.9 0.0 293.4 126.2 446.8 583.8 385.1 240.2 539.1 544.5 590.1 239.6 104.8 524.9 354.0 363.9 157.7 478.7 581.2 504.2 47.9 0.0 293.4 126.2 446.8 583.8 385.1 240.2 539.1 544.5 590.1 239.4 104.7 531.0 353.8 363.2 157.5 479.2 589.1 519.6 48.7 0.0 292.8 126.6 447.2 584.3 463.2 240.7 546.3 545.0 590.6 241.6 106.5 531.2 354.2 368.6 159.8 481.0 590.4 520.9 48.9 0.0 291.4 128.0 449.0 586.1 464.1 242.4 547.5 546.7 592.3 Remarks: Tsunami travel times in minutes (min). Page 96 of 110 Table A-4-6. Tsunami Travel Times of the coastal points at different sources. Coastal Point Datai Bay Banda Acheh Cape Leveque Chittagong Yangon Phuket Karachi Mahajanga Antsiranana Little Andaman North Andaman Baleshwar Trincomalee Salalah Djibouti Grand Gaube Male Mamoudzou Kismayo Dares Salaam S15_A_M8.0_D0 260.2 121.1 526.9 350.8 397.5 182.4 467.1 577.0 500.0 44.8 64.6 281.6 112.2 435.1 572.1 381.0 228.5 534.6 532.9 578.5 Source Point S15_D_M8.0_D0 S18_A_M8.0_D0 239.6 244.1 104.8 105.0 524.9 510.9 354.0 368.4 363.9 409.3 157.7 166.3 478.7 456.4 581.2 565.8 504.2 496.2 47.9 28.8 0.0 73.8 293.4 294.0 126.2 105.3 446.8 424.4 583.8 561.5 385.1 440.1 240.2 217.8 539.1 522.9 544.5 522.1 590.1 567.7 S18_D_M8.0_D0 222.6 86.0 517.2 380.5 364.2 140.7 471.1 578.9 509.4 33.2 53.9 308.4 121.2 439.2 576.3 451.9 232.6 536.0 536.6 582.2 Remarks: Tsunami travel times in minutes (min). Page 97 of 110 Table A-4-7. Comparison of Tsunami arrival times between TTT and directly obtained by numerical simulation at 1 m water depth. Coastal Point Datai Bay Banda Acheh Cape Leveque Chittagong Yangon Phuket Karachi Mahajanga Antsiranana Little Andaman North Andaman Baleshwar Trincomalee Salalah Djibouti Grand Gaube Male Mamoudzou Kismayo Dares Salaam TTT (min) Simulation (min) 239.6 226.55 104.8 88.37 524.9 580.40 354.0 316.39 363.9 342.71 157.7 136.92 478.7 492.46 581.2 597.79 504.2 505.16 47.9 19.68 0.0 3.88 293.4 250.38 126.2 110.66 446.8 450.72 583.8 616.05 385.1 450.33 240.2 202.23 539.1 555.92 544.5 522.37 590.1 579.20 Page 98 of 110 Table A-4-8. Comparison of Tsunami heights between Application of Green Law and directly obtained by numerical simulation at 1 m water depth. Coastal Point Datai Bay Banda Acheh Cape Leveque Chittagong Yangon Phuket Karachi Mahajanga Antsiranana Little Andaman North Andaman Baleshwar Trincomalee Salalah Djibouti Grand Gaube Male Mamoudzou Kismayo Dares Salaam Green Law (m) 0.20 0.35 0.03 0.63 0.77 0.45 0.02 0.03 0.10 0.88 4.69 0.69 0.42 0.08 0.02 0.07 0.11 0.04 0.11 0.08 Simulation (m) 0.10 0.19 0.02 0.31 0.05 0.16 0.02 0.02 0.09 0.42 1.52 0.09 0.26 0.04 0.01 0.07 0.05 0.02 0.08 0.11 Page 99 of 110 Appendix-5 Figure A-5-1. Tsunami propagation snapshots of Bengkulu Tsunami using TUNAMI-F1 in spherical coordinates system. Page 100 of 110 Time: 10 min Time: 30 min Time: 20 min Time: 40 min Figure A-5-2. Tsunami propagation snapshots of Bengkulu Tsunami using NAMIDANCE Version 4.7 in spherical coordinates system. Page 101 of 110 Figure A-5-3. Tsunami propagation snapshots of Bengkulu Tsunami using TUNAMI-N2 in Cartesian coordinates system. Page 102 of 110 Time: 10 min Time: 30 min Time: 20 min Time: 40 min Figure A-5-4. Tsunami propagation snapshots of Bengkulu Tsunami using NAMIDANCE Version 4.7 in Cartesian coordinates system. Page 103 of 110 Appendix-6 Table A-6-1. Tsunami heights at coastal points obtained by simple, interpolation, extrapolation and maximum risk methods. Coastal Point Datai Bay Banda Acheh Cape Leveque Chittagong Yangon Phuket Karachi Mahajanga Antsiranana Little Andaman North Andaman Baleshwar Trincomalee Salalah Djibouti Grand Gaube Male Mamoudzou Kismayo Dares Salaam Simple 1.69 6.28 0.26 0.90 1.01 2.18 0.41 0.41 1.06 1.94 1.03 1.14 1.78 0.92 0.20 0.68 1.99 0.74 1.66 1.05 Interpolation 1.11 3.89 0.36 0.67 0.73 1.43 0.39 0.43 1.17 1.44 0.99 0.76 1.26 0.82 0.15 0.58 1.38 0.54 1.44 0.87 Extrapolation 0.97 3.34 0.23 0.45 0.64 1.50 0.28 0.28 0.86 1.48 0.87 0.71 0.89 0.55 0.10 0.42 1.21 0.42 1.11 0.64 Maximum risk 1.69 6.28 0.50 1.03 1.01 2.18 0.49 0.54 1.52 2.02 1.26 1.14 2.65 1.26 0.21 0.88 2.03 0.74 1.89 1.30 Remark: Unit in metre (m) Page 104 of 110 Table A-6-2. Tsunami arrival times at coastal points obtained by simple, interpolation, extrapolation and maximum risk methods. Coastal Point Datai Bay Banda Acheh Cape Leveque Chittagong Yangon Phuket Karachi Mahajanga Antsiranana Little Andaman North Andaman Baleshwar Trincomalee Salalah Djibouti Grand Gaube Male Mamoudzou Kismayo Dares Salaam Simple 183.20 29.90 422.90 447.40 434.20 115.30 447.20 535.60 466.10 70.60 153.50 367.50 116.00 415.20 552.30 387.20 206.70 492.80 502.20 547.40 Interpolation 189.80 36.22 421.50 451.79 440.19 121.82 448.39 533.50 464.03 74.94 157.84 371.89 118.80 416.38 553.51 385.11 207.50 490.67 500.70 545.83 Extrapolation 183.20 29.90 422.90 447.40 434.20 115.30 447.20 535.60 466.10 70.60 153.50 367.50 116.00 415.20 552.30 387.20 206.70 492.80 502.20 547.40 Maximum risk 178.50 25.10 416.90 440.50 429.10 110.70 442.30 529.20 459.70 63.60 146.50 360.50 112.90 410.30 547.50 380.80 201.80 486.40 496.40 541.50 Remark: Unit in minutes (min) Page 105 of 110 Appendix-7 Start Inside Ranges No Fail Message Yes No 6.5≥M≤8.5 Yes Yes Within 15.7 km Simple Extrapolation No Interpolation Database Outputs End Figure A-7-1. 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