Strong controlling effect of stress evolution on the 2022 Ms5.0 Honghe earthquake sequence

Abstract

Understanding stress evolution patterns as a response to earthquake ruptures at geologically complex tectonic faults is vital because of the role of fault geometry as a source for the stress evolutionary constraints. Here, we analyze the 2022 Ms5.0 Honghe earthquake sequence and calculate the tectonic stress distribution of the two Ms. ≥ 3.5 earthquakes in this sequence. Results indicate that the focal mechanism type of the sequence obtained corresponds to strike-slip motion with an ESE-oriented strike and a steeply dipping NE-oriented nodal plane. The focal region is subjected to NNW-oriented horizontal compression and ENE-oriented horizontal tension. We find that the adjacent Ailaoshan fault constituted the major seismogenic fault of the mainshock and the regional stress field exerted a strong controlling effect on the associated postseismic events. Our results suggest that the stabilization of tectonic faults may help to enhance the effects of stress accumulation on the occurrence of medium-to-strong earthquakes.