青藏高原及周缘近年来典型强震地表破裂特征及其构造指示意义OA

[Objective]Coseismic surface ruptures provide key evidence for identifying the seismogenic structures of earthquakes,elucidating crustal deformation mechanisms,and assessing seismic hazards.To understand the surface deformation and disaster development characteristics associated with different types of fault activity on the Tibetan Plateau,and to reveal the current crustal deformation patterns reflected by a series of strong earthquakes in recent years,we systematically compiled and analyzed the surface rupture characteristics of five M>6.5 earthquakes that have occurred on the Tibetan Plateau and surrounding areas since 2021,based on field surveys.[Methods]We used the 2021 MW 7.4 Maduo,2022 MW 6.6 Menyuan,2022 MW 6.6 Luding,2024 MW 7.0 Wushi,and 2025 MW 7.1 Dingri earthquakes as representative cases.We integrated results from remote sensing interpretation,field surveys,and UAV photogrammetry,as well as seismological and geodetic data,to conduct a detailed analysis of the surface rupture and coseismic displacement distribution characteristics of these events.[Results]The strike-slip Maduo and Menyuan earthquakes formed coseismic surface rupture zones approximately 150～160 km and 22～31 km long,respectively,with maximum coseismic surface displacements of～3.6 m and～3.7 m.Contrastingly,the Luding earthquake,also a strike-slip event,exhibited a surface rupture only～450 m long at Ertaizi.The strong,MW 5.7 aftershock of the thrust-type Wushi earthquake generated a coseismic surface rupture zone～5 km long with a maximum vertical displacement of～1.7 m,while the normal-fault-type Dingri earthquake formed a coseismic surface rupture zone 25～36.5 km long with a maximum vertical displacement of～2.7 m.[Conclusions]A comprehensive analysis of the spatiotemporal distribution characteristics of major regional earthquakes indicates that,prior to the 2022 Luding earthquake,major earthquakes on the Tibetan Plateau were primarily clustered around the periphery of the active Bayan Har block.The subsequent Wushi and Dingri earthquakes both occurred far from the Bayan Har block,suggesting that the clustering period of major earthquakes in this active block may have ended.Further analysis of focal mechanism solutions indicates that strike-slip earthquakes have dominated recent moderate-to-strong seismic events on the Tibetan Plateau and its periphery.This may be related to the fact that current crustal deformation on the Tibetan Plateau is primarily regulated and absorbed through the lateral extrusion of active blocks along large strike-slip fault zones.[Significance]The above research findings provide fundamental data and references for earthquake early warning,disaster prevention and mitigation,as well as the planning,construction,and seismic design of major regional engineering projects in the Tibetan Plateau region.