摘要
为分析2021年5月21日云南省漾濞M_(S)6.4地震后震区应力变化对周围断层的影响,本文通过InSAR技术获得了漾濞地震的同震形变场,并联合小震分布数据建立断层破裂滑动模型,继而通过计算断层面上的同震库仑应力来评估此次地震对周边断层的影响,以便有效地分析地震破裂的时空解析度.结果显示:(1)在升降轨InSAR数据获得的精细同震形变场中,升轨最大视线向形变量约为5.00 cm,降轨最大视线向形变量约为7.80 cm;(2)余震精定位的主震震中为(99.89°E,25.67°N),震源深度为13.29 km,除主震之外震源深度主要集中在5—15 km;通过小震位置拟合出的发震断层走向为NW-SE(316.69°),断层倾角为88.56°,滑动角为177.97°;(3)基于InSAR同震形变场结果及小震拟合断层参数联合反演得到此次地震的断层滑动以右旋走滑为主,升轨断层最大滑动量为0.80 m,对应的深度为8.85 km,平均滑动量为0.22 m,矩震级为M_(W)6.41;降轨的断层最大滑动量为0.30m,对应的深度为6.88 km,平均滑动量为0.05 m,矩震级为M_(W)6.01;7.50 km和15 km深度处断层面上的应力计算结果表明,震后断层与其周围的应力差明显减小,对周围断裂具有显著的应力卸载作用.结合余震分布区域、模拟断层迹线以及同震库仑应力逐渐减小的方向,基本可以确定漾濞地震的发震断层为维西—乔后—巍山断裂的隐伏次生断裂.该地震通过卸载周围断裂的应力释放区域应力,降低了周围断裂的地震危险性.
In order to analyze the impact of stress changes on surrounding faults after the Yangbi M_S6.4 earthquake in Yunnan Province on May 21,2021,this paper used InSAR technology to perform the inversion for the coseismic deformation field of the Yangbi earthquake.Additionally,small earthquake distribution data was incorporated to establish a fault rupture sliding model.By calculating the coseismic Coulomb stress on the fault plane,the evaluation of the impact of earthquakes on surrounding faults was conducted.The analyses effectively examined the spatio-temporal resolution of earthquake rupture.The results indicate the following:(1) In the high-resolution coseismic deformation field obtained from the InSAR data of the ascending orbit,the maximum line of sight deformation is approximately 5.00 cm,while for the descending orbit it is around 7.80 cm.(2) The epicenter of the main shock of the Yangbi earthquake sequence,determined through precise positioning of aftershocks,is located at(99.89°E,25.67°N) with a focal depth of 13.29 km.Apart from the main shock,the focal depths of the aftershocks are primarily concentrated in the range of 5-15 km.By analyzing the location of small earthquakes,the strike of the seismogenic fault is is determined to be NW-SE(316.69°) with a dip angle 88.56° and a slip angle 177.97°.(3) Based on the joint inversion of InSAR coseismic deformation field result and small earthquake fitting fault parameters,it was determined that the fault slip during this earthquake was primarily dextral strike-slip.The maximum slip amount observed during the ascending orbit was 0.80 m,corresponding to a depth of 8.85 km.Additionally,the average slip amount was measured to be 0.22 m,and the moment magnitude of the earthquake is M_W6.41.The maximum slip of the fault during the descending orbit is 0.30 m,corresponding to a depth of 6.88 km.The average slip amount during this orbit is measured to be 0.05 m,and the moment magnitude of the earthquake is M_W6.01.Furthermore,stress calculations on fault planes at th
作者
王小怡
徐克科
刘新奇
张墨思
王帅鹏
Wang Xiaoyi;Xu Keke;Liu Xinqi;Zhang Mosi;Wang Shuaipeng(School of Surveying and Land Information Engineering,Henan Polytechnic University,Henan Jiaozuo 454003,China)
出处
《地震学报》
CSCD
北大核心
2023年第5期849-862,共14页
Acta Seismologica Sinica
基金
国家自然科学基金(41774041)资助。
