联合高频GNSS和强震数据快速反演四川泸定6.8级地震断层破裂特征

北京时间2022年9月5日12时52分, 四川甘孜藏族自治州泸定县发生6.8级地震.利用震中附近1 Hz高频GNSS观测数据获取了同震速度和位移波形, 并快速测定了泸定地震的震中和震级.实验结果表明: 高频GNSS反演的震中与美国地质调查局(USGS)发布的震中相差32 km, 与中国地震台网中心发布值相差16 km; 高频GNSS反演的震级, 与两个机构均仅差0.1个震级单位.针对地震预警、震后快速响应等时效性应用, 提出了一种联合高频GNSS和强震数据的线源破裂特征快速反演方法.泸定地震实验结果表明: 在震后20 s时可获得稳定的线源模型, 破裂长度、方向和破裂模式值分别为33.3 km、151°和0.6, 破裂方向与USGS震源机制解断层走向相差14°, 反演的断层破裂模式为双侧破裂.提出的地震断层破裂特征快速反演方法可用于地震预警、震后灾害快速评估以及紧急响应, 同时可为今后联合高频GNSS和强震数据快速测定地震破裂特征提供参考.

Rapid inversion of fault rupture characteristics for the Luding M6.8 earthquake in Sichuan with high-rate GNSS and strong-motion data

The M6.8 earthquake struck Luding County, Garzê Tibetan Autonomous Prefecture in Sichuan Province on 5 September 2022 at 12∶52 AM Beijing local time. The near-field 1 Hz high-rate GNSS data are processed to obtain velocity and displacement waveforms, which are then used to rapidly estimate the epicenter and magnitude of the earthquake. The epicenter determined by high-rate GNSS is 32 km from the epicenter issued by the USGS (United States Geological Survey) and 16 km from that by the CENC (China Earthquake Networks Center), whereas the retrieved magnitude is just 0.1 magnitude units different from that of the two institutions. Combing high-rate GNSS and strong-motion data, we present a rapid inversion method of fault rupture characteristics, with which a stable line-source model can be obtained 20 s after origin time. The rupture length, direction, and pattern values are 33.3 km, 151°, and 0.6, respectively. The estimated rupture direction is 14° away from the fault strike of the USGS focal mechanism, and a bilateral rupture pattern is indicated by the fault rupture pattern value. The proposed method can be applied to earthquake early warning, rapid disaster assessment, and emergency response. The outcomes can provide a reference for the future study of rapidly estimating fault rupture characteristics using high-rate GNSS and strong-motion data.