The North Tabriz fault is a segmented dextral fault in Northwest Iran, with a history of major destructive earthquakes that have repeatedly destroyed the city of Tabriz（current population 1.6 million）. The quiescenc...The North Tabriz fault is a segmented dextral fault in Northwest Iran, with a history of major destructive earthquakes that have repeatedly destroyed the city of Tabriz（current population 1.6 million）. The quiescence of the fault（last major temblor in 1854） and a lack of outcrop study have hampered stress analysis. Resolution of the stress states on the fault could be used for seismotectonic study along the North Tabriz fault and for understanding the geodynamics of the Arabia-Eurasia collision zone. Using fault-slip data collected from 88 localities in the fault system, we conducted an inversion analysis of this fault-slip data and analysis of the stratigraphic, geometric, and structural information. As a result, we confirmed that transcurrent deformation is prevalent on the North Tabriz fault and adjacent areas and is generally accomplished by predominant NW-SE-trending dextral and NE-SW-trending sinistral faults. Specifically, three separate tectonic episodes are recognised from the stress inversion data, consistent with the geologic data：（i） a post-Cretaceous and pre-Early Miocene compressional（Laramian） stress regime,（ii） an Early Miocene extensional stress regime, and（iii） modern tectonic episode with different local stress regimes（compressional and extensional） along the different segments of this fault.展开更多
Azerbaijan is one of the most active segments of the Alpine-Himalayan seismic belt and marks the junction between the African-Arabian and Indian plate to the south and Eurasian plate to the north. Several regional ear...Azerbaijan is one of the most active segments of the Alpine-Himalayan seismic belt and marks the junction between the African-Arabian and Indian plate to the south and Eurasian plate to the north. Several regional earthquakes have been strongly felt and caused damages in and around Tabriz during history. For example, the magnitude 7 to 7.7 Tabriz earthquake in 1780, which is the most strongest experienced one in Lesser Caucasus and east of Turkey and caused severe damage in Azerbaijan territory including Tabriz City. The urban area of Tabriz City lies on Miocene to Quaternary soft sediments （clays, sands, silts, and gravels.） resting on an old Tertiary basement. Previous studies have shown that the thickness of such soft sediments could largely influence the site response in case of an important regional earthquake. The accurate information about historical earthquakes and new faulting is an important tool for viewing the active tectonic and analyzing the earthquake risk and seismic migration. Historical records of earthquakes in Tabriz based on macro and micro seismic observations cover period of 1,000 to 1,400 years. Our study aims at mapping the seismic response of a pilot zone of Tabriz for different earthquake scenarios, a simple but robust.展开更多
The occurrence of the historical and machine Earthquakes, near to the North Tabriz Fault in NW Iran is an evidence for the seismic activity of this fault, which records a historical earthquake with a magnitude more th...The occurrence of the historical and machine Earthquakes, near to the North Tabriz Fault in NW Iran is an evidence for the seismic activity of this fault, which records a historical earthquake with a magnitude more than 7. Using the existing experimental relations, seismicity, and the fault geometry, a Mw 7.7 earthquake scenario was defined. The stochastic finite-fault modeling based on a dynamic corner frequency shows good agreement with common attenuation patterns. The shake map illustrates that Baghmisheh, Roshtieh, Ellahieh, Valiamr, and Eram region on Tabriz are at high hazard areas, and the maximum acceleration is located at the north direction with the same azimuth similar to fault strike.展开更多
文摘The North Tabriz fault is a segmented dextral fault in Northwest Iran, with a history of major destructive earthquakes that have repeatedly destroyed the city of Tabriz（current population 1.6 million）. The quiescence of the fault（last major temblor in 1854） and a lack of outcrop study have hampered stress analysis. Resolution of the stress states on the fault could be used for seismotectonic study along the North Tabriz fault and for understanding the geodynamics of the Arabia-Eurasia collision zone. Using fault-slip data collected from 88 localities in the fault system, we conducted an inversion analysis of this fault-slip data and analysis of the stratigraphic, geometric, and structural information. As a result, we confirmed that transcurrent deformation is prevalent on the North Tabriz fault and adjacent areas and is generally accomplished by predominant NW-SE-trending dextral and NE-SW-trending sinistral faults. Specifically, three separate tectonic episodes are recognised from the stress inversion data, consistent with the geologic data：（i） a post-Cretaceous and pre-Early Miocene compressional（Laramian） stress regime,（ii） an Early Miocene extensional stress regime, and（iii） modern tectonic episode with different local stress regimes（compressional and extensional） along the different segments of this fault.
文摘Azerbaijan is one of the most active segments of the Alpine-Himalayan seismic belt and marks the junction between the African-Arabian and Indian plate to the south and Eurasian plate to the north. Several regional earthquakes have been strongly felt and caused damages in and around Tabriz during history. For example, the magnitude 7 to 7.7 Tabriz earthquake in 1780, which is the most strongest experienced one in Lesser Caucasus and east of Turkey and caused severe damage in Azerbaijan territory including Tabriz City. The urban area of Tabriz City lies on Miocene to Quaternary soft sediments （clays, sands, silts, and gravels.） resting on an old Tertiary basement. Previous studies have shown that the thickness of such soft sediments could largely influence the site response in case of an important regional earthquake. The accurate information about historical earthquakes and new faulting is an important tool for viewing the active tectonic and analyzing the earthquake risk and seismic migration. Historical records of earthquakes in Tabriz based on macro and micro seismic observations cover period of 1,000 to 1,400 years. Our study aims at mapping the seismic response of a pilot zone of Tabriz for different earthquake scenarios, a simple but robust.
文摘The occurrence of the historical and machine Earthquakes, near to the North Tabriz Fault in NW Iran is an evidence for the seismic activity of this fault, which records a historical earthquake with a magnitude more than 7. Using the existing experimental relations, seismicity, and the fault geometry, a Mw 7.7 earthquake scenario was defined. The stochastic finite-fault modeling based on a dynamic corner frequency shows good agreement with common attenuation patterns. The shake map illustrates that Baghmisheh, Roshtieh, Ellahieh, Valiamr, and Eram region on Tabriz are at high hazard areas, and the maximum acceleration is located at the north direction with the same azimuth similar to fault strike.
