地球与行星物理论评（中英文）2026，Vol.57Issue(6)：684-699,16.DOI:10.19975/j.dqyxx.2026-001
2025年定日MW7.1地震同震形变特征及断层滑动分布
Coseismic deformation and fault slip distribution inversion of the 2025 MW7.1 Dingri,Xizang,earthquake
摘要
Abstract
On January 7,2025,an MW7.1 earthquake struck Dingri County,Xigaze City,on the southern mar-gin of the Qinghai-Xizang Plateau,China.The epicenter was located at the intersection between the southern seg-ment of the Shenzha-Dingjie Rift and the South Xizang Detachment System,a tectonically complex region charac-terized by active extensional deformation.The earthquake induced large-amplitude coseismic surface deformation with a highly heterogeneous spatial distribution.To clarify the seismogenic structural characteristics and fault slip distribution of this event,we conducted a systematic investigation by integrating Interferometric Synthetic Aper-ture Radar(InSAR)observations with seismic source mechanism and fault slip inversion methods.(1)The InSAR-derived deformation fields reveal that the coseismic deformation was dominated by a nearly north-south-trending subsidence zone,with a maximum line-of-sight(LOS)subsidence of approximately 1.4 m and a maximum uplift of about 0.9 m.The two-dimensional deformation field further indicates pronounced subsidence accompanied by westward horizontal motion on the western side of the fault,while the eastern side exhibits relative uplift and east-ward motion.These deformation characteristics suggest that the earthquake rupture was primarily governed by nor-mal faulting,with a minor strike-slip component.(2)Based on the assumption of a homogeneous elastic half-space,a single-fault model was first employed to invert the observed coseismic deformation,yielding the optimal geomet-ric parameters for the Dengmocuo Fault,with a strike of 184.6° and a dip angle of 54°.Although this single-fault model satisfactorily explains the major deformation features in the vicinity of the main fault,significant residual de-formation remains on the western side of the fault.This result indicates the inherent limitations of a single planar fault model in fully reproducing the complete spatial pattern of the observed deformation field.(3)To reasonably account for the residual deformation,a conjugate double-fault model was introduced for joint inversion.The results demonstrate that the earthquake rupture was dominated by a west-dipping main fault,accompanied by the syn-chronous rupture of an east-dipping,high-angle subsidiary fault.Both faults exhibit typical normal-faulting charac-teristics.Compared with the single-fault model,the conjugate double-fault model significantly improves the de-formation fitting accuracy,particularly within incoherent zones near the subsidiary fault,and provides a more com-prehensive explanation for the overall observed deformation pattern.Assuming a shear modulus of 30 GPa,the joint inversion based on the double-fault model yields a total seismic moment of approximately 3.69×1019 N·m,corresponding to a moment magnitude of MW7.03.The results indicate that the 2025 Dingri earthquake represents a typical conjugate normal-faulting rupture event within the southern Xizang Rift System.This study highlights the important role of conjugate fault systems in strain partitioning and energy release in extensional tectonic settings and provides valuable insights into the regional deformation mechanisms and seismic hazard assessment of the southern Qinghai-Xizang Plateau.关键词
定日地震/InSAR观测/同震变形/共轭正断层/断层滑动分布Key words
Dingri earthquake/InSAR observations/coseismic deformation/conjugate normal faults/fault slip distribution分类
天文与地球科学引用本文复制引用
张礼杰,苏小宁,高志钰,黄家乐,虞思晗,杨丹..2025年定日MW7.1地震同震形变特征及断层滑动分布[J].地球与行星物理论评（中英文）,2026,57(6):684-699,16.基金项目
国家自然科学基金资助项目(42574050,42174003) （42574050,42174003）
兰州市人才创新创业资助项目(2023-RC-31) Supported by the National Natural Science Foundation of China(Grant Nos.42574050,42174003),and the Lanzhou Talent Innova-tion and Entrepreneurship Project(Grant No.2023-RC-31) （2023-RC-31）
