Are strain rate lows proxies of low-potential of strong earthquakes? A case study in Western China

Abstract

Strain accumulation is closely related to the occurrence of strong earthquakes. To investigate the pre-seismic deformation status of strong earthquakes, the correlation between the GNSS (Global Navigation Satellite System) strain rates and earthquakes subsequent to the GNSS observation period in Western China was studied. The primary results show that a large part of M_W ≥ 6.0 earthquakes occurred in the medium and low value regions (MLVR) of the second invariant of strain rate (SR). Meanwhile, about 81 % of strike-slip earthquakes occurred in the MLVR of the maximum shear strain rate, and the ratios are 72 % and 100.0 % for the reverse-faulting and normal-faulting earthquakes in the MLVR of principal compressive and tensile strain rates, respectively. The sustained slow fault slip rates, complex faults in different stages of inter-seismic period, and historical earthquakes, may possibly cause the typical strain rate patterns for the pre-seismic stage. Therefore, Mw ≥ 6.0 earthquakes possibly occur in MLVR of strain rates, and low strain rate is not an indicative of low-potential of strong earthquakes.