The Source Characteristics of the 2022 Ms 6.1 Lushan Earthquake: An Event That Occurred on the Conjugated Fault of the 2013 Ms 7.0 Lushan Earthquake

Abstract

Abstract The 2022 Ms 6.1 Lushan earthquake occurred in the southern segment of the Longmenshan fold-and-thrust belt, Sichuan Province, China, ∼7 km north-northwest of the 2013 Ms 7.0 Lushan earthquake. To understand its source characteristics and interplay with the 2013 Lushan event, we evaluate the 2022 Lushan earthquake in terms of focal mechanism, aftershock relocation, and rupture process. Results show that it is a purely thrust earthquake with a source depth of 14 km and a focal mechanism nodal plane of 29°/51°/80°. The automatic phase picker-based aftershock locus clarifies that the 2022 Lushan earthquake occurred on a blind northeast-trending conjugate fault of the 2013 Lushan earthquake. The finite-fault model constrained by teleseismic waveforms suggests that the high slip is concentrated in an asperity near the epicenter with a peak slip of 42 cm, which is characterized by thrust components. Based on the promotion of postseismic deformation following the 2013 Lushan earthquake and the similarity of the seismotectonic system, we argue that the 2022 Lushan earthquake may be an aftershock of the 2013 Lushan earthquake that occurred on a blind thrust fault.