Focal mechanism of 2022 Menyuan MS6.9 earthquake in Qinghai Province

On Jan. 8, 2022, a strong earthquake with surface magnitude up to MS6.9 occurred in Menyuan region, Qinghai Province. To understand its tectonic implication, focal mechanism and centroid depth of the major event are inverted by CAP method. The inversion results show that the event is dominated by a strike-slip focal mechanism with a very shallow centroid depth (3 km). Combining with the spatial orientations of relocated aftershocks, we confirm the rupture plane 284°/82°/21° (strike/dip/rake). The focal mechanism is different with those events including the 1986 and 2016 M6.4 Menyuan earthquakes, implying the complex crustal deformation in this region. The results provide fundamental information for seismic hazard in this region.