Hu Yaping, Yuji Yagi, Ryo Okuwaki , Ryo Yamaguchi, Gao Hangyu

On September 5, 2022, a strike-slip earthquake with a moment magnitude (Mw) 6.7 occurred along the Moxi segment of the Xianshuihe fault zone in Luding, Sichuan province, China. To estimate the rupture evolution of the 2022 Luding earthquake, we inverted teleseismic P-waves by applying the Potency Density Tensor Inversion, a novel method that can estimate fault geometry and source process. We found the rupture process can be divided into two episodes. In the first episode, the initial deep rupture continues for 2 second on a westward tilting fault plane. In the next episode (3 to 7 s), the main rupture propagated along the Xianshuihe fault zone toward the south-southeast and halts ~15 km south-southeast from the epicentre. An isolated rupture also occurred ~10 km west from the Xianshuihe fault zone. The main rupture propagated in a south-southeast direction where strain have been accumulating, and our resolved strike direction rotated counterclockwise as it propagated from the epicentre to south-southeast. The along-strike migration of the main rupture stopped in a region with a complex fault network, and the along-dip migration did not go through the shallow-most region to the surface. Our seismic source model suggests that the 2022 Luding earthquake has failed to cascade up to a lager event, contrary to the last largest 1786 Kangding-Luding earthquake in this region, due to the fault geometry and shallow sedimentary layers inhibiting rupture propagation.