Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Earthquake Home » Geological Disasters » Earthquake Earthquake is a sudden shaking of ground due to natural causes (rock displacements, landslide, avalanche, volacanic eruption, meteoritic impact, sub-marine sea faulting, etc) so to refer it as natural earthquake. The shaking of ground may be due to several other man-made agencies, such as, explosions due to chemical blasts or nuclear blasts or rock burst due to mining activities, and reservoir induced earthquakes. Occurrence of earthquake is still a puzzle for the entire scientific community as its generating mechanism does not follow a thumb rule. It can hit anywhere at any point of time and that is why earthquake is regarded as most unpredictable, uncontrollable and unfathomable cause of bringing disasters to both flora and fauns. Scale of disaster due to earthquake is dictated by several earthquake parameters. Among which are earthquake magnitude (extent of energy release during the earthquake), focal depth or hypocenter (the depth at which the rupture initiates), the epicenter location of the earthquake (the vertical projection of the hypocenter to the surface). Thus bigger magnitude earthquake at shallower depth (< 30 km) with its epicenter location near the densely populated region can inflict a severe damage to both property and person, whilst the reverse may lead to relatively less damaging effects in the earthquake prone zones. In addition to that earthquake occurrence time and building typology also play their important roles in influencing the degree of damage due to earthquakes in the region. It is rightly said that “earthquake does not kill the people; it is structure which kills the people”! Several pieces of studies revealed that upper crust of the earth up to a depth of 18 km from the surface is seismically active because of its brittle behavior, while lower crust between 18 km and 33 km depth inside the earth is seismically less active due its ductility under high temperature. The boundary between the lower crust and upper crust is referred to as Conrad discontinuity, while the boundary between the lower Crust and the upper Mantle is referred to as Mohorovicic discontinuity, in short it is mentioned as Moho discontinuity, which varies from shallower (10 – 12 km) beneath the Ocean to deeper (70 – 80 km) beneath the Himalaya. The entire crust and upper Mantle constitute “Lithosphere”, whose thickness is found to varying from 100 km to 150 km. It is a solid lithosphere which floats on the semi-viscous layer of the earth called Aesthenosphere, a part of the lower Mantle. The lithosphere constitutes an important ingredient of Earth’s physiographic that divides entire Earth into several tectonic blocks to explain the geodynamics of the Earth and seismogenesis in diverse tectonic environ. Earthquake can hit either within the same tectonic block / plate (intra-plate earthquake) or at the boundary of two or more tectonic plates (plate-boundary earthquakes). The plate-boundary earthquakes are frequent (e.g., earthquakes in Himalayan region; earthquakes in the Andaman – Nicobar region; earthquakes in the Ring of Fire zone, Alaska, Japan, Chile ), while the intra-plate earthquakes are less frequent (e.g., earthquakes in stable continental region of India; the 1819 Kutchch earthquake; 1993 Latur earthquake; 2001 Bhuj earthquake). The great damaging earthquakes are generally accompanied with secondary effects, such as tsunamis, liquefactions, landslides, volcanic (lava and mud) eruptions; nuclear emissions, and fires that may multiply the degree of losses due earthquake many folds. The recent occurrence of the 2004 tsunami-genic Sumatra – Andaman earthquake (Mw 9.3) and the 11th March 2011 Japan tsunamigenic earthquake ( Mw 9.0) are appropriate example to understand how a huge loss of both people and property was mainly due to secondary effect of tsunamis rather than that of primary earthquake shakings. Occurrence of damaging Earthquakes are a major problem for the mankind, killing more than 17000 persons per year in the twentieth century. It causes multifaceted damages and destruction to life and property. What to do about earthquake risk and how to mitigate earthquake induced damages, particularly in the developing countries, has been a challenging issue and still need a coordinated effort to tackle the regional menace that occur during the killer earthquakes. Assessing the earthquake risk and determining mitigation alternatives varies from country to country. Reduction in the earthquake risk involves the use of knowledge, methodologies adopted based on the geopolitical boundaries. More so on multi-objective-multi-stake holder decision to be taken. Making a decision on what to do, depends on the site specific data collected from affected region, including multifaceted role played by geosciences, engineering, disaster planning and response, techno-legal, insurance and economics. Several earthquakes in the recent past remind us about the high level of seismic hazard and risk prevailing in the country. About 59% of India's land area is under the threat of moderate to severe earthquake shaking intensity VII and higher. During the last two decades, several major earthquakes have resulted in over 100,000 deaths in South Asian nations, especially located in the vicinity of Himalaya and in the oceanic subduction zone of Andman – Nicobar Island region . The regions far away from the Himalaya and other inter-plate boundaries, which were once considered to be relatively safe from strong shaking, have also experienced several devastating earthquakes. The huge losses of life and property in the earthquake-prone areas of the region have shown that the built-environment is extremely fragile, and our ability to respond to these events is extremely inadequate. It has been found that the casualties were caused primarily due to the collapse of buildings that have usually no earthquake-resistant features. This emphasizes the need for strict compliance of town planning bye-laws and earthquake-resistant building codes in India. About Earthquake Can we predict earthquakes? Seismicity of south Asia Important organizations in India Early warning and prediction Preventive and mitigation measures How can I protect myself during an earthquake? Scale About Earthquake Weblinks About Earthquake What is an Earthquake? An earthquake is the motion or trembling of the ground produced by sudden displacement of rock in the Earth's crust. Earthquakes result from crustal strain, volcanism, landslides, and collapse of caverns. Stress accumulates in response to tectonic forces until it exceeds the strength of the rock. The rock then breaks along a preexisting or new fracture called a fault. The rupture extends outward in all directions along the fault plane from its point of origin (focus). The rupture travels in an irregular manner until the stress is relatively equalized. If the rupture disturbs the surface, it produces a visible fault on the surface. Earthquakes are recorded by seismograph consisted of seismometer, a shaking detector and a data recorder. The moment magnitude of an earthquake is conventionally reported, or the related and mostly obsolete Richter magnitude, with magnitude 3 or lower earthquakes being mostly imperceptible and magnitude 7 causing serious damage over large areas. Intensity of shaking is measured on the modified Mercalli scale. In India Medvedev-Sponheuer-Karnik scale, also known as the MSK or MSK-64, which is a macro-seismic intensity scale, is used to evaluate the severity of ground shaking on the basis of observed effects in an area of the earthquake occurrence. Due to earthquake seismic waves are generated and measurements of their speed of travel are recorded by seismographs located around the planet. There are two main types of seismic waves - body and surface waves. The body waves have Primary (P-) and secondary (S-wave) types. Demonstration of seismic waves are explained here Demo Why earthquake occurs? Earthquakes occur due to the sudden release of stored strain energy inside the earth crust. The earth is divided into several major and micro tectonic plates, some 50 miles thick, which move slowly and continuously over the earth's aesthenosphere. Most earthquakes occur as the result of slowly accumulating stress that causes the ground to slip abruptly along a geological fault plane on or near a plate boundary. The resulting waves of vibration within the earth create ground motion at the surface that vibrates in a very complex manner. What are the various types of earthquake? Classification of earthquake is based on several parameters. Based on scale of magnitude (M), earthquake may be of Micro (M < 3.5) or macro (M > 3.5) type. Depending up on the extent of energy released and strength of the ground shaking it may be of several types, like moderate strong, very strong, great and very great earthquake. Depending up on the scale of damage, the earthquake may be of various types, such as Less damaging earthquake, Moderate damaging earthquake, and catastrophic earthquake. Depending up on the focal depth (h) of the event, it could be shallow earthquake (d< 70 km); intermediate depth earthquake (70 < h < 300 km); the deep earthquake (300 < h < 700 km). Depending up on the location of events in different tectonic settings, earthquake may be of intra-plate, inter-plate, and sub-oceanic earthquake. Depending up on involvement of other agencies / phenomena with earthquake genesis, it may be of several types, such as Reservoir induced; Fluid-driven earthquake; Tsunamigenic earthquake, and volcanic earthquake. Depending up on the type of faulting involved during earthquake genesis, earthquake may be categorized into several categories, such as normal faulting, reverse faulting, thrust faulting, and mega-thrust earthquake. Depending up on the frequency content, the earthquake may be of Low-Frequency tremors or high – Frequency tremors. Depending up on the epicenter distance (distance between earthquake mainshock and the recording stations), the earthquake may be classified into Local, Regional and Global earthquake. For more Information Click here (types of earthquakes). What one should know about earthquakes? Earthquakes can be violent, and they remain unpredictable. A comprehensive background note on the earthquakes for commoner is given in the earthquake tips prepared by several institutions of SAARC countries, like India, Bhutan, Nepal and Pakistan. Intensity scale It manifests the degree of damage, which gets diminished as we go away from the main shock source zone and the reverse is also true. There are several earthquake intensity scale, which can be referred from the relevant pages. European http://en.wikipedia.org/wiki/European_Macroseismic_Scale USA (MM) http://en.wikipedia.org/wiki/Mercalli_intensity_scale Japan (JMA) http://en.wikipedia.org/wiki/Japan_Meteorological_Agency_seismic_intensity_scale Can we predict earthquakes? Can we predict Earthquakes? With present state of knowledge of science, it is not possible to predict earthquake. It is so because the physics involved in earthquake genesis is very complex. The mechanism of earthquake generating processes is still not adequately understood us because of involvement of multicomponent parameters in earthquake genesis. For more Information Click here There are several school of thoughts on the earthquake prediction, notable among is Jim Berkland, a retired geologist from USGS, who, according to his supporters, has 80% accuracy rates. Recently a book by Cal Orey was released. For more Information Click here South Asian Profile Most parts of south Asian countries (Afghanistan, Bhutan, India, Nepal and Pakistan) are seismically very vulnerable because of their close proximity to the young and dynamic Himalayan belt, extending from Northwest to Northeast. There were several past damaging earthquakes hit the countries of south Asia, especially by large magnitude earthquakes that inflicted a huge loss to both property and person (please see Table 1). Most recently, the 2005 Muzaffrabad earthquake (Mw 7.6) caused a huge loss of property and lives of people of Kashmir. About 85,000 people reported to have killed during the earthquake. The 1934 Nepal – Bihar earthquake (Mw 8.0) was another example that killed about 12,000 people of two countries, Nepal and India. India's high earthquake risk and vulnerability is evident from the fact that about 59 per cent of India's land area could face moderate to severe earthquakes. During the period 1990 to 2006, more than 23,000 lives were lost due to 6 major earthquakes in India, which also caused enormous damage to property and public infrastructure. The occurrence of several devastating earthquakes in areas hitherto considered safe from earthquakes indicates that the built environment in the country is extremely fragile and our ability to prepare ourselves and effectively respond to earthquakes is inadequate. Some facts on Indian earthquake risk scenario can be found. The building collapse results in the widespread loss of lives and property including lifeline infrastructure like roads, dams and bridges, hospitals as well as public utilities like power and water supply installations. Past earthquakes have shown that over 95 per cent of the lives lost were due to the collapse of buildings that were not earthquake-resistant. Though there are no. of earthquake resistant design codes and other regulations available proper implementation of these urgently requires serious attention. India has advanced considerably in developing earthquake resistant codes of practice and guidelines for constructing RCC and steel framed buildings, brick or stone masonry buildings and combination of clay, wood, bamboo and thatched houses. Yet high level of earthquake risk in our country�s context is mostly attributed to the unplanned and ill planned urban infrastructures developments. In order to reduce vulnerability it is important to create proper awareness about earthquake induced damages and their mitigation measures. During the International Decade for Natural Disaster Reduction (IDNDR) observed by the United Nations (UN) in the 1990s, India witnessed several earthquakes like the Uttarkashi earthquake of 1991, the Latur earthquake of 1993, the Jabalpur earthquake of 1997, and the Chamoli earthquake of 1999. Some of the photographs of Indian earthquakes are available here Click here These were followed by the Bhuj earthquake of 26 January 2001 and the Jammu & Kashmir earthquake of 8 October 2005. All these major earthquakes established that the casualties were caused primarily due to the collapse of buildings. However, similar high intensity earthquakes in the United States, Japan, etc., do not lead to such enormous loss of lives, as the structures in these countries are built with structural mitigation measures and earthquake-resistant features. The National Information Center of Earthquake Engineering hosted at Indian Institute of Technology Kanpur is intended to collect and maintain information resources on Earthquake Engineering and make these available to the interested professionals, researchers, academicians and others with a view to mitigate earthquake disasters in India.Various initiatives taken up by Ministry of Home Affairs. For more Information Click here Some of the important issues in earthquake risk mitigation in Indian context are: Earthquake hazard and risk mitigation Earthquake resistant design and rehabilitation of structures Indian standards and guidelines on earthquake technology Seismic evaluations and retrofitting of lifeline buildings Disaster safe construction practices and issues Techno-legal and techno-financial framework for earthquake protection compliance Training and Capacity building of masons, architect and engineers India Govt. initiatives in the earthquake risk reduction For more Information Click here Global Profile Globally, earthquakes have caused massive destruction upto the present day. It represents a risk to many countries of the world, particularly western North and South America, Japan, China, the Phillipines, New Zealand, northern part of India and the middle east region. Most recently, about 20,000 people were reported either killed or missing during the great mega-thrust tsunamigenic Japan earthquake (Mw 9.0) that struck on 11th March 2011 beneath the NE Japan forearc region. Besides, a great killer earthquake of magnitude (Mw 7.9) hit Haiti in January 2010 in which about 223,000 people were killed. Other earthquake which caused a severe loss to property and person during the year 2010 are China and Chile earthquake. A comprehensive details of earthquake as a science and understanding of various facts that lead to enormous damages and Real time seismic monitor of the earth destructions are available here Click here. Early warning and prediction Earthquake early warning Earthquake early warning (EEW) can provide a few seconds to tens of seconds warning prior to ground shaking during an earthquake. Several countries, such as Japan, Taiwan, Mexico have adopted this methodology based on the fact that such warning can (1) rapidly detect the initiation of an earthquake, (2) determine the size (magnitude) and location of the event, (3) predict the peak ground motion expected in the region around the event, and (4) issue a warning to people in locations that may expect significant ground motion. For more Information Click here While there is strong need for comprehensive training in the emergency response some tips for EEW in Japan are enlisted here Click here Humanitarian early warning service (HEWS) provides information on various hazards, including earthquake. For more Information Click here Prediction of earthquake is still a subject of speculations yet several schools of thoughts are available. In the effort to predict earthquakes, people have tried to associate an impending earthquake with such varied phenomena as seismicity patterns, electromagnetic fields, weather conditions and unusual clouds, radon or hydrogen gas content of soil or ground water, water level in wells, animal behavior, and the phases of the moon. For more Information Click here Earthquake early warning system Earthquake early warning provides an alarm that strong shaking is due soon to arrive, and the more quickly that the magnitude of an earthquake can be estimated, the more useful is the early warning. Receiving a warning, a person may have a few tens of seconds at longest to take actions, but if the focus is too close there may be cases in which strong tremors come ahead. For more Information Click here Preventive and mitigation measures When earthquake strikes a building is thrown mostly from side to side, and also up and down along with the building foundation the building structure tends to stay at rest, similar to a passenger standing on a bus that accelerates quickly. Building damage is related to the characteristics of the building, and the duration and severity of the ground shaking. Larger earthquakes tend to shake longer and harder and therefore cause more damage to structures For more Information Click here Structural No buildings can be made 100% safe against earthquake forces. Instead buildings and infrastructures can be made earthquake resistant to certain extent depending upon serviceability requirements. Earthquake resistant design of buildings depends upon providing the building with strength, stiffness and inelastic deformation capacity which are great enough to withstand a given level of earthquake-generated force. This is generally accomplished through the selection of an appropriate structural configuration and the careful detailing of structural members, such as beams and columns, and the connections between them For more Information Click here There are several different experimental techniques that can be used to test the response of structures to verify their seismic performance, one of which is the use of an earthquake shaking table (a shaking table, or simply shake table). This is a device for shaking structural models or building components with a wide range of simulated ground motions, including reproductions of recorded earthquakes time-histories. To view the list of shaking Table Click here Nonstructural The non-engineered traditional construction commonly practiced in different areas of the country depends greatly on the respective local context of the area. In other words the technologies vary significantly from area to area. These technologies have evolved and as a result have got optimized. In India an overwhelming majority of houses, are of non-engineered load bearing type. These structures, especially houses, have been traditionally built over the past century or longer, using the locally available materials and the locally practiced technologies that have been most common in the area including stone, bricks, earth, lime and timber for walls, and clay tiles, stone or mud for roofing supported on under-structure made of local timber such as Teak, Acacia, Neem, Deodar, Pine and also Bamboo. In the recently built structures one also finds a mix of the traditional and new materials/technology such as cement, concrete and steel. The structures have pitched roof or flat roof, and are single story or double story. After Bhuj earthquake significant effort were taken to repair and strengthening of damaged buildings. A guideline for Repair and strengthening guide for earthquake damaged lowrise domestic buildings in Gujarat is made available here Click here Seismic retrofitting Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. With better understanding of seismic demand on structures and with our recent experiences with large earthquakes near urban centers, the need of seismic retrofitting is well acknowledged. For more Information Click here EQ and liquefaction weblinks http://www.ce.washington.edu/~liquefaction/html/links/links.html Liquefaction http://www.ce.washington.edu/~liquefaction/html/main.html Geotechnical EQ engineering http://www.geoengineer.org/learnbyhy-earthquake.aspx Scale Richter Approximate Magnitude Approximate TNT for Seismic Energy Yield Joule equivalent Example 0.0 1 kg (2.2 lb) 4.2 MJ 0.5 5.6 kg (12.4 lb) 23.5 MJ Large Hand grenade 1.0 32 kg (70 lb) Construction site blast 1.5 178 kg (392 lb) 747.6 MJ WWII conventional bombs 2.0 1 metric ton Late WWII conventional bombs 2.5 5.6 metric tons 23.5 GJ WWII blockbuster bomb 3.0 32 metric tons 134.4 GJ Massive Ordnance Air Blast bomb 3.5 178 metric tons 747.6 GJ Chernobyl nuclear disaster, 1986 4.0 1 kiloton 4.2 TJ Small atomic bomb 4.5 5.6 kilotons 23.5 TJ 134.4 MJ 4.2 GJ 5.0 32 kilotons 134.4 TJ Nagasaki atomic bomb (actual seismic yield was negligible since it detonated in the atmosphere. The Hiroshima atomic bomb was 15 kilotons ) Lincolnshire earthquake (UK), 2008 5.4 150 kilotons 625 TJ 2008 Chino Hills earthquake (Los Angeles, United States) 5.5 178 kilotons 747.6 TJ ittle Skull Mtn. earthquake (NV, USA), 1992 Alum Rock earthquake (CA, USA), 2007 6.0 1 megaton 4.2 PJ Double Spring Flat earthquake (NV, USA), 1994 6.5 5.6 megatons 23.5 PJ Rhodes (Greece), 2008 6.7 16.2 megatons 67.9 PJ Northridge earthquake (CA, USA), 1994 6.9 26.8 megatons 112.2 PJ San Francisco Bay Area earthquake (CA, USA), 1989 7.0 32 megatons 134.4 PJ 7.1 50 megatons 210 PJ Energy released is equivalent to that of Tsar Bomba, the largest thermonuclear weapon ever tested. 7.5 178 megatons 747.6 PJ Kashmir earthquake (Pakistan), 2005 Antofagasta earthquake (Chile), 2007 7.8 600 megatons 2.4 EJ Tangshan earthquake (China), 1976` 8.0 1 gigaton 4.2 EJ Toba eruption 75,000 years ago; which, according to the Toba catastrophe theory, affected modern human evolution San Francisco earthquake (CA, USA), 1906 Queen Charlotte earthquake (BC, Canada), 1949 México City earthquake (Mexico), 1985 Gujarat earthquake (India), 2001 8.5 5.6 gigatons 23.5 EJ Sumatra earthquake (Indonesia), 2007 9.0 32 gigatons 134.4 EJ Lisbon Earthquake (Lisbon, Portugal), All Saints Day, 1755 9.2 90.7 gigatons 379.7 EJ Anchorage earthquake (AK, USA), 1964 9.3 114 gigatons 477 EJ Indian Ocean earthquake, 2004 (40 ZJ in this case) 9.5 178 gigatons 747.6 EJ Valdivia earthquake (Chile), 1960 (251 ZJ in this case) 10.0 1 teraton 4.2 ZJ Never recorded. Richter Description Magnitudes Frequency of Occurrence Earthquake Effects Less than 2.0 Micro Microearthquakes, not felt. About 8,000 per day 2.0-2.9 Minor Generally not felt, but recorded. About 1,000 per day 3.0-3.9 Minor Often felt, but rarely causes damage. 49,000 per year (est.) 4.0-4.9 Light Noticeable shaking of indoor items, rattling noises. Significant damage unlikely. 6,200 per year (est.) 5.0-5.9 Moderate Can cause major damage to poorly constructed buildings over small regions. At most slight damage to well800 per year designed buildings. 6.0-6.9 Strong Can be destructive in areas up to about 160 kilometres (100 mi) across in populated areas. 120 per year 7.0-7.9 Major Can cause serious damage over larger areas. 18 per year 8.0-8.9 Great Can cause serious damage in areas several hundred miles across. 1 per year 9.0-9.9 Great Devastating in areas several thousand miles across. 1 per 20 years 10.0+ Epic Never recorded; see below for equivalent seismic energy Extremely rare yield. (Unknown) (Based on U.S. Geological Survey documents.) JMA Scale Shindo scale Magnitu deShindo Number (Shindo Number People in Japanes e) / Meter reading Reinfor ced Indoor Outdoor Wooden concret situation situatio Lifelines houses e s ns building s Ground and slopes Peak ground accelerat ion 0 (0) / 00.4 Impercept ible to people. Less than 0.008 m/s² 1 (1) / 0.5-1.4 Felt by only some people in the building. 0.008– 0.025 m/s² 2 (2) / 1.5-2.4 Felt by most people in the building. Hanging objects such as lamps swing 0.025– 0.08 m/s² Some people awake. Felt by most people in the building. Some people are frightened . slightly Dishes in a cupboard rattle occasional ly Electric wires swing slightly 0.08–0.25 m/s² 4 (4) / 3.5-4.4 Many people are frightened . Some people try to escape from danger. Most sleeping people awake. Hanging objects swing considera bly and dishes in a cupboard rattle. Unstable ornaments fall occasional ly. Electric wires swing considera bly. People walking on a street and some people driving automobil es notice the tremor. 0.25–0.80 m/s² 5-lower (5弱) / 4.5-4.9 Hanging objects swing violently. Most Most people try Unstable to escape ornaments from a fall. danger. Occasional Some ly, dishes people in a find it cupboard difficult to and books move. on a bookshelf fall and furniture moves. People notice electriclight poles swing. Occasiona lly, windowpa nes are broken and fall, unreinforc ed concreteblock walls collapse, and roads suffer damage. Occasion ally, less earthquak eresistant houses suffer damage to walls and pillars. Occasion ally, cracks are formed in walls of less earthquak eresistant buildings. Occasion ally, A safety device cracks cuts off the gas appear in service at some soft houses. On rare ground. occasions water and pipes are rockfalls 0.80–1.40 damaged and and small m/s² water service is slope interrupted. failures (Electrical service take is interrupted at place in some houses) mountain ous districts 5-upper (5強) / 5.0-5.4 Most dishes in a cupboard and most books on a bookshelf fall. Occasional ly, a TV set on a rack falls, heavy furniture In many cases, unreinforc ed concreteblock walls collapse and tombston es overturn. Many automobil Occasion ally, less earthquak eresistant houses suffer heavy damage to walls and pillars and lean. Occasion ally, large cracks are formed in walls, crossbea ms and pillars of less earthquak eresistant buildings Occasion ally, cracks Occasionally, gas appear in pipes and / or soft water mains are ground. damaged.(Occasi and 1.40–2.50 onally, gas service rockfalls m/s² and / or water and small service are slope interrupted in failures some regions) take place in mountain 3 (3) / 2.5-3.4 Many people are considera bly frightened and find it difficult to move. such as a chest of drawers falls, sliding doors slip out of their groove and the deformati on of a door frame makes it impossible to open the door. es stop because it becomes difficult to drive. Occasiona lly, poorlyinstalled vending machines fall. and even highly earthquak eresistant buildings have cracks in walls. ous districts. 6-lower (6弱) / 5.5-5.9 Occasion ally, less earthquak A lot of eheavy and resistant unfixed In some houses furniture buildings, collapse moves wall tiles Difficult to and even and falls. and keep walls and It is windowpa standing. pillars of impossible nes are highly to open damaged earthquak the door and fall ein many resistant cases. houses are damaged. Occasion ally, walls and pillars of less earthquak eresistant buildings are destroyed and even highly earthquak eresistant buildings have large cracks in walls, crossbea ms and pillars. Gas pipes and / or water mains are damaged.(In some regions, gas service and water service are interrupted and electrical service is interrupted occasionally.) Occasion ally, cracks appear in the 2.50–3.15 ground, m/s² and landslides take place. 6-upper (6強) / 6.0-6.4 Many, less earthquak eresistant houses collapse. In some cases, even walls and pillars of highly earthquak eresistant houses are heavily damaged. Occasion ally, less earthquak eresistant buildings collapse. In some cases, even highly earthquak eresistant buildings suffer damage to walls and pillars. Occasionally, gas mains and / or water mains are damaged.(Electric al service is interrupted in some regions. Occasionally, gas service and / or water service are interrupted over a large area.) Occasion ally, cracks appear in the 3.15–4.00 ground, m/s² and landslides take place. ost heavy and unfixed Impossibl furniture e to keep moves standing and falls. and to Occasional move ly, sliding without doors are crawling. thrown from their groove. In many buildings, wall tiles and windowpa nes are damaged and fall. Most unreinforc ed concreteblock walls collapse. 7 (7) / 6.5- up In most buildings, wall tiles and Thrown by Most windowpa the furniture nes are shaking moves to damaged and a large and fall. impossible extent In some to move and some cases, at will. jumps up. reinforced concreteblock walls collapse. Occasion ally, even highly earthquak eresistant buildings are severely damaged and lean. Occasion ally, even highly earthquak eresistant buildings are severely damaged and lean. The ground is considera bly distorted by large cracks and Electrical service fissures, gas service and and slope water service are failures interrupted over a and large area. landslides take place, which occasiona lly change topograp hic