基于构造应力场研究2025年西藏定日6.8级地震的发震构造  

INVESTIGATION OF THE SEISMOGENIC STRUCTURE OFTHE 2025 DINGRI M_(S)6.8 EARTHQUAKE IN XIZANG BASEDON THE TECTONIC STRESS FIELD PERSPECTIVE

作　　者：盛书中 王倩茹 李振月 李红星 张小娟 葛坤朋 宫猛 SHENG Shu-zhong;WANG Qian-ru;LI Zhen-yue;LI Hong-xing;ZHANG Xiao-juan;GE Kun-peng;GONG Meng(School of Geophysics and Measurement-control Technology,East China University of Technology,Nanchang 330013,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)

机构地区：[1]东华理工大学,地球物理与测控技术学院,南昌330013 [2]中国地震局地球物理研究所,北京100081

出　　处：《地震地质》2025年第1期49-63,共15页Seismology and Geology

基　　金：国家自然科学基金(42364005,42174074,42442401);江西省科技计划项目(20232ACB213013)共同资助。

摘　　要：双力偶模型给出的震源机制解的2个节面具有等效性,需要借助于其他资料或方法识别其中的发震断层面,基于应力场识别震源机制解2个节面中的发震断层面即为方法之一。基于GCMT的震源机制解,文中将上述方法应用于2025年1月7日西藏定日6.8级地震发震构造的研究,获得以下结论:1)震源区最大主压应力轴近直立,最大主张应力轴近水平且方向近EW,为正断层型应力场;2)2025年1月7日西藏定日6.8级地震的发震断层为震源机制解中走向S、倾向W的节面,为一次正断层型地震,推断其发震断层为登么错断裂;3)该地区历史地震发震断层面的识别结果显示西藏定日地区历史地震的发震断层走向S,倾向W,倾角范围为37°~48°,断层类型为正断层。文中结果为该次地震发震构造的研究提供了地震学证据,可为相关发震构造研究提供参考。On January 7, 2025, at 09:05 Beijing Time, an M_(S)6.8 earthquake struck Dingri County in Shi-gatse City, Xizang, as reported by the China Earthquake Networks Center. The earthquake occurred at 28.50° -N, 87.45° -E with a hypocentral depth of 10km, resulting in significant casualties and economic losses. In the immediate aftermath, major earthquake research institutions and seismo-logists, both domestic and international, promptly released the focal mechanism solution, providing crucial data for understanding the earthquake's origin and its seismogenic structure. However, the two nodal planes of the focal mechanism, derived from a double-couple source model, are equivalent, necessitating additional data or methodologies to distinguish the actual seismogenic fault plane. The parameters of the seismogenic fault are fundamental for the accurate calculation of ground motion maps, and they provide key information for seismic hazard assessment and post-earthquake rapid response guidance. Therefore, it is imperative to identify the seismogenic fault plane for the given focal mechanism solution.This study employs the tectonic stress field in the source region of the Dingri earthquake to calculate the instability coefficients of the two nodal planes, selecting the most unstable plane as the actual seismogenic fault. This method is based on the tectonic stress field to identify the seismogenic fault plane in the two nodal planes of the focal mechanism solution. The approach is applied to identify the seismogenic fault plane of the Dingri earthquake and nearby historical seismic events.Using the Global Centroid Moment Tensor(GCMT)focal mechanism solution, the study inverts the shallow tectonic stress field in the source region. The results reveal the maximum principal compressive stress axis is nearly vertical, and the maximum principal tensile stress axis is nearly horizontal with a strike orientation of E-W, which is a normal faulting stress regime. The stress field result is consistent with the normal faulting characte

关 键 词：西藏定日地震 应力场 断层不稳定系数 震源机制解节面 发震断层 

分 类 号：P315.2[天文地球—地震学]