Stress triggering and future seismic hazards implied by four large earthquakes in the Pamir from 2015 to 2023 revealed by Sentinel-1 radar interferometry

Abstract

Summary The Mw 6.8 Murghob earthquake is the third earthquake in an Mw 6.4+ sequence occurring in the Pamir initiated by the 2015 Sarez Mw 7.2 earthquake. It is of great significance to investigate their interactions and to assess future seismic hazards in the region. In this paper, we use Sentinel-1 radar interferometric data to retrieve coseismic deformation, invert for the slip distributions of the four events, and then investigate their interactions. The cumulative Coulomb failure stress changes (ΔCFS) suggest that the 2023 Murghob earthquake was promoted by the three prior earthquakes in the sequence. Pre-stress from historical earthquakes is a key factor in explaining the triggering mechanism of the two 2016 Mw 6.4+ earthquakes. Stress loading and unloading effects on major faults in the region indicate that future attention should be paid in 1) the segment of the Sarez-Karakul fault north of the Kokuibel Valley, 2) the segment of the Sarez-Murghab thrust fault west of the Sarez-Karakul fault, and 3) the east segments of the Pamir thrust fault system, all with a large positive ΔCFS.