固体地球物理研究生学术报告第六期（一）

The Pamir plateau, sited on the north of the Western Himalaya, is the collisional tectonics of two continental blocks. The west-east extension and north-south shortening of the interior Pamir was caused by the ongoing northern extrusion of the Indian plate. The western and central Pamir exhibits a higher faulting deformation, including sinistral strike-slip with northeast or north-northeast striking and extensional faulting. The Mw 7.2 Murghab, Tajikistan earthquake of 7th December 2015 is the first earthquake larger than Mw 7 documented by both the seismic and geodetic technical in Pamir interior. The mainshock attacked on the Sarez-Karakul fault zone (SKF), extending from south of Sarez Lake to north of Karakul lake. We collected five pairs InSAR interferograms and construct five line-of-sight displacements, including the ascending and descending orbits of ALOS-2 and Sentinel-1A. We process the seismic waveforms from the European Union (EU) and Global Seismological networks (GSN). We combine near-field geodetic observations and seismic waveforms to invert refined model about earthquake ruptures. Our results show that the geometry of the seismogenic fault is complex in striking direction (218° for the southern segment, 240° for the central segment, 212° for the northern segment) and rupture features present the different range from the pure striking to the mainly normal along the NS-SW fault trace. The length of the main rupture zone is up to 100 km and its slip reaches to the surface. The average slip is about 2.5 m and its area is in size of the 100 km × 20 km in length and width. The geodetic moment is up to 1.125 × 10²⁰ N∙m, equivalent with a Mw 7.31. The distributed shearing and normal slip of the 2015 Mw 7.2 Tajikistan earthquake imply the tectonics and activation of the Sarez-Karakul fault system in the inland of Pamir. Furthermore, if we assume the 2015 Mw 7.2 Tajikistan earthquake to be the characteristic event on the Sarez-Karakul fault zone, the accumulated strain of the northern SKF should not be fully released by this strong event, and a potential seismic risk still exists in this region.