Focal Mechanism and Seismogenic Structure of the MS 5.1 Qingbaijiang Earthquake on February 3, 2020, Southwestern China

The 3 February 2020 M S 5.1 Qingbaijiang earthquake, southwestern China, is the closest recorded ? 5.0 event to downtown Chengdu City date, with an epicentral distance of only 38 km. Here we analyze seismic data from Sichuan and regional networks, employ a multi-stage location method relocate earthquakes that have occurred along central northern segments Longquanshan fault zone since 2009, including earthquake sequence, investigate seismogenic structure region. relocation results indicate seismicity has mainly eastern branch hypocentral distribution vertical cross-section illustrating steep, NW-dipping parallel imbricate structure. terminating depth about 12 sequence NE–SW-striking zone. aftershock focal depths are in 3–6 km range, mainshock located at 104.475°E, 30.73°N. Its initial rupture 5.2 indicates above shallow decollement layer upper crust this long axis area highlights dipping 56° NW. Our surface projection inferred plane places it near We infer be thrust faulting based on mechanism solution via cut-and-paste waveform inversion method, strike/dip/rake parameters 22°/36°/91° 200°/54°/89° obtained for nodal planes I II, respectively. identify lies zone, II represents coseismic plane, joint analysis results, mechanism, geological information. study provides vital information assessing hazard City.