B. Nurtaev1 , S. Zenkova1
1Institute of Geology and Geophysics
Abstract:
The tectonics of Central Asia are dominated by the spectacular collision between India and Asia. For the Central Asia region the largest center of seismic activity is the deep-focus (90-300 km) Pamir-Hindu Kush earthquake zone. The spatial placement of earthquake foci in the area (100-150 km by 700 km), the high level of seismicity and repeatability of events and the compactness displayed by the various focal zones, provides a unique opportunity to study natural events that have different source parameters but nearly the same ray paths. We revised strong motion attenuation specifically from Hindu Kush and Pamir seismic zones by searching the records of seismic stations of Uzbekistan, Tadjikistan and Kyrghystan. Variation in time delays with azimuth and epicentral distance appears to be due to the varying angles between the ray path and the principal axes of the anisotropic system. We have found a significant number of repeating earthquakes with reversed polarity waveforms, which may suggest repeating rupture on sub-parallel faults but with reversed slip directions. Comparative analysis of the time of Pamir-Hindu Kush earthquakes and the formation of large landslides in the period from 1969 to 2018 showed agreement for more than 200 cases of landslides formed in South Kyrghystan, Uzbekistan and Tajikistan.
