Far-field coseismic gravity changes related to the 2015 MW7.8 Nepal (Gorkha) earthquake observed by superconducting gravimeters in mainland China

Abstract

Using data from five SGs at four stations in mainland China, obvious permanent gravity changes caused by the 2015 MW 7.8 Nepal (Gorkha) earthquake were detected. We analyzed the gravity effects from ground vertical deformation (VD) using co-site continuous GPS (cGPS) data collocated at the Lijiang and the Wuhan station, and hydrological effects using GLDAS models and groundwater level records. After removing these effects, SG observations before and after the earthquake revealed obvious permanent gravity changes: −3.0 μGal, 7.3 μGal and 8.0 μGal at Lhasa, Lijiang and Wuhan station, respectively. We found that the gravity changes cannot be explained by the results of dislocation theory.