Interseismic and coseismic deformation of the 2023 Jishishan MS6.2 earthquake determined by GNSS and InSAR data

Abstract

Quantitative studies on the interseismic and coseismic deformation characteristics and analysis of the interplay between the seismogenic fault and neighboring faults are crucial for understanding the kinematic features and assessing potential seismic hazards. In this study, the interseismic and coseismic deformation of the 2023 Jishishan MS6.2 earthquake (JSSEQ), including the strain rate filed, the slip rates, and locking depths of the seismogenic fault during the interseismic period, were obtained. Moreover, the coseismic slip distribution and geometric attributes of the seismogenic fault were further examined. Finally, the potential earthquake hazard in the vicinity was identified by analyzing the Coulomb failure stress changes (ΔCFS). Before the JSSEQ, the maximum shear and dilatational strain rates near the epicenter were significantly lower, and the seismogenic fault was strongly coupled with thrust and dextral strike-slip motion. The maximum displacement of GNSS stations is about 25 mm, about 11 km southwest of the epicenter. The ascending and descending observations reveal a significantly thrust-dominated movement, with maximum line of sight displacements of 78 and 83 mm, respectively. Comparing two coseismic slip distribution results and previous studies, it is considered that the east dipping seismogenic fault is more reasonable. The coseismic fault slip took place at a depth of 7.1–13.2 km, with a maximum slip of 0.43 m and a moment magnitude of 6.1. The earthquake resulted in noticeable stress loading on the southeastern end of the Lajishan north margin fault zone and the Lajishan south margin fault zone, as well as the western end of the West Qinling fault zone, which should be given more attention in future.