Seismic risk assessment of Badakhshan region (northeast Afghanistan)

Document Type : Research Article

Authors

• Khadijeh Mohammadi ¹
• Ebrahim Moghimi ²
• Mehdi Zare ³
• Mojtaba Yamani ²
• Masoud Mojarab ⁴

¹ Tehran University

² University of Tehran

³ IIEES

⁴ International Institute of Seismology

10.22067/geoeh.2023.79118.1287

Abstract

Badakhshan region, in the northeast of Afghanistan, has a complex geology. A catalog from 2011-2021 was prepared using the data of the Middle Asia seismic catalog with updates (years 1909-2011) from the website of the American Geological Survey. Considering the last earthquake with a magnitude of 7.2 in 2015, the coefficients of b were calculated to the maximum value of 1.0 and a to the value of 7.9 in the surface and depth, the increase in the numerical values of a and b in the central half has been fully evident. The results indicate that; The current trend is opposite to the direction of the main fault in North Badakhshan (north-south direction). The highest frequency of earthquakes ≥4 occurs at a depth of 150-70 km, earthquakes ≥5 at a depth of 150-300 km, and finally, earthquakes ≥6 at a depth of 150-300 km occur in the east-west direction. This area is exactly where the Pamir Corridor plate meets the center of Badakhshan. This shows that at the end of the Pamir Corridor from east to west, ruptures are being created at depths of 0-150 km. Two east-west and east-south trends are evident. Regarding the shallow earthquakes related to the upper 50 km of the crust, the dominant mechanism is of the normal type, which indicates the stretching of the crust in this section. According to the deep mechanism of earthquakes, the direction of the tensile force is in the east-west direction. This issue further confirms the issue of continental collision and then subduction towards the south of Badakhshan. The innovation of this research is the identification of seismic trends that have rarely been researched in the studied area, and its application is to identify high-risk areas for construction.

Keywords

• Hindu Kush
• morphotectonic
• Badakhshan
• Afghanistan

Main Subjects

• مخاطرات ژئومورفیک-هیدرولوژیک

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