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New Challenges in the European Area: Young Scientist’s 1st International Baku Forum New Challenges in the European Area: Young Scientist’s 1st International Baku Forum Relation between seismicity and tectonic structures within Azerbaijan part of the Greater Caucasus. Fuad Aliyev [email protected] Institute of Geology, ANAS 21 - 25 May, 2013 Baku, Azerbaijan Objectives • Spatial distribution peculiarities of earthquakes • Studying of relationship between recent tectonic movements with seismicity • Revelation of active parts of tectonic faults Allocation of accretionary prism within Caucasus structure The Greater Caucasus has formed during last stage of the tectogenesis in a geodynamic condition of the lateral compression, peculiar to the zone of pseudosubduction interaction between Northern and Southern Caucasian continental microplates. Collision of Arabian plate with Eurasian plate Azerbaijan is located within active collision zone of Arabian and Eurasian plates. Actually observing continental collision characterized by the movement of Arabian plate to North direction and displacement of Anatolian plate to western, and Iranian plate to eastern direction and compression of the Great Caucasus. Earthquakes that occur in Azerbaijan territory give us information about dynamics of deep faults, structure of earth’s crust, allow tracing active zones of the faults, and can reveal peculiarities of spatial distribution of strong earthquakes. Plate tectonic reconstructions provide broad constraints on the timing of the initial collision of the Arabian Plate with Eurasia, and indicate that the rate of northward motion of Arabia relative to Eurasia has remained more or less constant at about 20 mm/yr since collision began. Earthquakes that occur in Azerbaijan territory give us information about dynamics of deep faults, structure of earth’s crust, allow tracing active zones of the faults, and can reveal peculiarities of spatial distribution of strong earthquakes. Seismicity Seismology Database : Seismicity of the territory of a republic has been analyzed on the basis of the earthquakes’ catalogue NEIC USGS – National Earthquake Information Center of US Geology Survey IRIS – Incorporated Research Institutions for Seismology ISC – International Seismological Centre CTBTO – Comprehensive Nuclear-Test-Ban Treaty Org. RCSS ANAS – Seismology Survey Center, Azerbaijan Seismicity Seismology Database : Unified catalogue of earthquakes for 427-2010 Totally 960 seismic events . Representation, М≥4 for 427-1902 Representation, М≥3 for 1903-2010 Map of seismicity with М≥3 for 427 – 2010 Map of Strong earthquakes occurred in Azerbaijan historically Strong earthquakes occurred in Azerbaijan historically Year Month Day 427 21 Fi La H M Region 40,5 46,5 12,0 6,7 Ganja 39,60 45,40 12 7.0 735 7 1139 9 40,3 46,2 23,0 7,7 Ganja 1235 10 40,4 47,0 20,0 6,3 Ganja 1667 40,9 48,2 20,0 7,0 Shemakha 1668 41,0 48,0 6,8 1828 40,7 48,4 5,7 Shemakha 1842 1 2 40,5 50,0 0,0 4,7 Mashtaga 1859 6 12 40,7 48,5 12,0 6,1 Shemakha 1868 3 21 40,2 46,8 30,0 6,3 Zurnabad 40,7 48,7 5,0 Shemakha 1869 1872 1 29 40,6 48,7 7,0 6,0 Shemakha 1875 3 22 39,2 47,6 11,0 6,5 Iran 1902 2 16 40,7 48,5 18,0 6,9 Shemakha Map of Strong earthquakes occurred in Azerbaijan (427-2010) Map of maximum intensities 42 9 8.5 41 8 7.5 7 40 6.5 6 5.5 39 5 4.5 45 46 47 48 49 50 51 52 Map of maximum intensity distribution One of the most important aspects of seismic hazard estimation is the calculation of earthquake occurrence possibility with different intensity values in any place without indication of time, whenever any seismic event may take place (Riznichenko Yu. V., 1979). Such analyzes and calculations for Azerbaijan territory have been conducted before (Kadirov F.A., et al., 2008), using data from instrumental registered earthquakes. So far as the data about intensities for pre-instrumental earthquakes haven’t been used before, we have included those too for our calculations. For the plotting of a map of maximal intensity, the area of study has been equally gridded by 20x20 km cells of 0.5 degrees . By the use of combined catalogues, for each cell, the intensity value from each earthquake has been calculated using the following equation I 1.4M 3.5lg(R) 3.5 R h x 2 2 Riznichenko Yu. V. Seismic shakability of USRR territory.1979 42 9 8.5 41 8 7.5 7 40 6.5 6 5.5 39 5 4.5 45 46 47 48 49 50 51 52 Map of Maximum Earthquake intensities for the period 427-2010 42 9 8.5 41 8 7.5 7 40 6.5 6 5.5 39 5 4.5 45 46 47 48 49 50 51 52 From the map of maximum intensities of earthquakes we can observe that the zones subjected to strong earthquakes distributed irregularly. The isolines of high intensity of earthquakes comply with the regional deep faults. This conformity can be observed in collision zone along Main Caucasus Thrust, located on the Southern slope of the Greater Caucasus in Shamakhy-Ismailli seismic zone, and then alongside the fault, in a Caspian Sea basin southward from Absheron peninsula. The same situation is also observed in a Lesser Caucasus along the KizilagajVandam, Kura and Fore-Lesser Caucasus faults. 42 9 M-K 8.5 41 8 7.5 АГД ГКН 40 КУР 7 К-В ПМК 6.5 6 НАХ 5.5 39 5 4.5 45 46 47 48 49 50 51 52 Map of Maximum Earthquake intensities for the period 427-2009 Earthquakes distribution within 1º area for 1902-2010 Collision of Arabian plate with Eurasian plate GPS horizontal motion rates for Azerbaijan and adjacent areas Cureently running GPS network of Azerbaijan, establuished by the Institute of Geology, ANAS in cooperation with MIT in different parts of a pepublic, and two continious real-time GPS stations. Distribution of Seismic Energy released from zones Energy (J) 5E+15 4E+15 3E+15 2E+15 1E+15 0 I II III IV Zones Map of Earthquake foci zones of the North-West Azerbaijan (I – Zagatala, May, 2012, II – Balaken, October, 2012, III – Sheki, May, 2012 This fact of recent seismic activity is particularly proved by earthquakes which have taken place between May and December, 2012 in Zagatala, Sheki and Balakan. Geological-geophysical section through focal zone of Zagatala earthquakes Focal zone of the earthquake is confined to a complex intersection knot of different strike faults, and is located in Pre-Jurassic basement. The very seismic event is mainly related with activity of Zagatala fault with northwestern strike which caused activation of connected dislocations. Geological-geophysical section through focal zone of Balakan earthquakes Focal zone of the earthquake is confined to a complex intersection knot of the faults with various strike, and is located in the upper part of Pre-Jurassic basement. Fig.19. Geological-geophysical section through focal zone of Sheki earthquakes Earthquake's focal zone is situated in the upper part of Pre-Jurassic basement. Seismic event is connected with activity of subvertical faults with northeastern dir. Conclusions. - According to the distribution of GPS rates along MCT, there exist 4 zones with different values of tectonic stress. - From the map of maximum intensities of earthquakes we can observe that the zones subjected to strong earthquakes distributed irregularly. - At the junction of MCT with K-V fault zone, located in Shamakhy region we observe earthquakes with maximum intensities. - Hypocenters of major seismic events (М = 4,5-5,7) and absolute majority of aftershocks are confined to a pre-Jurassic basement's surface or its' depths of up to 20 km (from 2012 events); - In general the seismic activity of a mentioned period is explained by accumulation of lateral compression stresses and their later discharge in an underthrust articulation line of Middle Kur and Vandam tectonic zones along Ganikh-Ayrichay-Alat deep overthrust. Thanks for Attention !!! Fuad Aliyev