利用远场记录反演2023年甘肃积石山M6.2地震破裂过程

Inversion of the Rupture Process of the 2023 Jishishan M6.2 Earthquake in Gansu by Teleseismic Data

2023年12月18日23时59分在甘肃临夏积石山发生了M6.2地震,地震发震断层推测为此前尚未充分认知的积石山东缘断裂。本文利用远场地震记录反演分析了2023年积石山M6.2地震的破裂过程。结果表明,地震破裂持续时间约8 s,主要破裂长度为20~25 km,宽度约25 km。在走向为164°的节面Ⅰ上,整个破裂过程释放的标量地震矩为1.46×10^(18)N·m,相当于矩震级MW6.05,最大同震滑动量约为0.25 m,估计矩心深度为9.5 km,破裂主要沿断层走向SSE向扩展;在走向为303°的节面Ⅱ上,释放的标量地震矩为1.38×10^(18)N·m,相当于矩震级MW6.03,最大同震滑动量约为0.19 m,矩心深度为11.1 km。破裂呈现双侧形态,主要沿SE方向,并存在NW向的拓展趋势。

This study utilized teleseismic data to invert and analyze the rupture process of the 2023 Jishishan M6.2 earthquake in Gansu,China.The causative fault of the earth-quake was likely to be a previously unclear local fault,the Jishishan eastern margin fault.The results indicated that the earthquake rupture lasted approximately 8 s,with a primary rupture length of 20~25 km and a width of about 25 km.On the nodal plane I with a strike of 164°,the entire rupture process released a scalar seismic moment of 1.46×10^(18)NN·m,equivalent to a moment magnitude of Mw6.05 with a maximum coseismic slip of 0.25 m.The estimated centroid depth was 9.5 km and the rupture primarily extended in the south-southeast direction along the fault strike.On the nodal plane II with a strike of 303°,the scalar seismic moment released was 1.38×10^(18)NN·m,equivalent to a moment magnitude of Mw6.03,with a maximum coseismic slip of 0.19 m and a centroid depth of 11.1 km.The rupture exhibited a bilateral pattern,predominantly extending in the south-east direction,with a northwestward expansion trend.