2023年12月18日,甘肃省临夏回族自治州积石山县发生了 Ms 6.2级地震,地震灾害损失显著高于同震级地震,查明其同震形变场与断层滑动分布特征,有助于揭示此次地震灾害损失严重的原因.利用Sentinel-1卫星升、降轨雷达影像,采用合成孔径雷达干涉技术获取了本次地震的同震形变场,进而基于Okada弹性位错模型,确定了本次地震的震源参数,并基于分布式滑动模型反演了本次地震断层面上的滑动分布.结果表明,积石山地震为逆冲型地震,升、降轨同震形变场沿视线向最大形变量分别为7.1 cm和7.8 cm,断层最大滑动量为0.31 m,主要集中在地下0～8 km.与2019年6月17日四川长宁Ms 6.0级地震对比发现,长宁地震地表最大形变量为8 cm,断层最大滑动量为0.38 m,均大于积石山地震,推测积石山地震灾害损失严重的主要原因为震区居民房屋相对集中、房屋抗震性能差和黄土区场地地震波放大效应等.
Abstract
On December 18,2023,an Ms 6.2 earthquake occurred in Jishishan County,Linxia Hui Autonomous Prefecture,Gansu Province.The seismic losses were significantly higher than those of earthquakes of the same magnitude.Identifying the coseismic deformation field and fault slip distribution characteristics will help reveal the reasons for the severe losses caused by this earthquake disaster.The coseismic deformation field of this earthquake is obtained using ascending and descending orbit radar images obtained with the Sentinel-1 satellite and synthetic aperture radar interferometry.Based on the Okada elastic dislocation model,the source parameters of this earthquake are determined,and the sliding distribution on the fault plane of this earthquake is inverted using a distributed sliding model.The results indicate that the Jishishan earthquake was a thrust-type earthquake,with maximum deformation fields along the line of sight for the ascending and descending tracks of 7.1 cm and 7.8 cm,respectively.The maximum sliding amount of the fault was 0.31 m,mainly concentrated 0-8 km underground.In comparison,the Changning Ms 6.0 earthquake in Sichuan on June 17,2019 had a maximum surface deformation of 8 cm and the maximum slip of the fault was 0.38 m,both larger than inferred for the Jishishan earthquake.It is speculated that the main reasons for the severe damage caused by the Jishishan earthquake are the relative concentration of residential buildings in the seismic area,the poor seismic performance of the buildings,and the amplification effect of seismic waves in the loss area.
万方数据