High‐resolution seismic tomography of the 2015 <i>M_w</i>7.8 Gorkha earthquake, Nepal: Evidence for the crustal tearing of the Himalayan rift

Abstract

Abstract The M w 7.8 Gorkha earthquake struck Nepal and ruptured the boundary between the Indian and Eurasian plates. We conducted 2‐D Pg wave tomography to clarify the seismogenic structure and try to understand causal mechanisms for this large earthquake, using the aftershock data recorded by 15 broadband seismic stations located near the China‐Nepal border. Our high‐resolution results show that coseismic slip area of the main shock is consistent with the high P wave velocity anomaly, and the region of maximum slip has a larger area with higher velocity than the region of initial slip, possibly resulting in the dominant low‐frequency radiation of energy observed after the dominant high‐frequency radiation of energy in the source rupture process. The boundary between these regions of contrasting high and low seismic velocity anomalies suggests a potential crustal tearing at the southern end of the Tangra Yum Co Rift, possibly resulting from different thrust speeds in the Greater Himalaya.