基于震前-震后高精度地形点云数据提取三维地表同震位移场信息  

THREE-DIMENSIONAL SURFACE COSEISMIC DISPLACEMENTS FROM DIFFERENCING PRE-AND POST-EARTHQUAKE TERRAIN POINT CLOUDS

作　　者：魏占玉[1,2] 何宏林[1,2] 邓亚婷 席茜 WEI Zhan-yu;HE Hong-lin;DENG Ya-ting;XI Xi(State Key Laboratory of Earthquake Dynamics and Forecasting,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Taiyuan Continental Rift Dynamics National Field Scientific Observation and Research Station,Beijing 100029,China)

机构地区：[1]地震动力学与强震预测全国重点实验室(中国地震局地质研究所),北京100029 [2]山西太原大陆裂谷动力学国家野外科学观测研究站,北京100029

出　　处：《地震地质》2025年第1期167-188,共22页Seismology and Geology

基　　金：国家重点研发计划项目(2021YFC3000601);中国地震局地质研究所基本科研业务专项(IGCEA1607)共同资助。

摘　　要：地震破裂带附近同震位移和变形模式对于深入理解地震破裂过程、断层行为及活动断层与地形地貌关系等至关重要。文中提出一种迭代最近点(ICP)算法,利用地震前后地形点云进行差分确定断层近场三维同震地表位移。在川西大凉山断裂带交际河断层上选取2期SfM地形点云叠加同震位移场模拟震前-震后点云,测试ICP方法获取同震位移场的精度。该方法在网格边长>50m的条件下可准确恢复同震位移场的方向和幅度,水平和垂直精度分别为20~10cm,这与地形点云定位精度相当。随着点云密度和网格窗口尺寸减小,该方法恢复同震位移场等的精度将降低。通过分析树木生长、房屋建设、河流侵蚀等地形变化对恢复位移场的潜在影响,研究结果表明扩大网格尺寸可使震前-震后点云具有足够地形结构进行匹配,以减小局部地形变化对恢复位移场的影响,网格窗口尺寸是在具有足够地形结构的大尺度和具有更精细分辨率的小尺度之间的权衡。文中所述的ICP方法利用震前-震后高精度点云可获取地震破裂带附近精细的三维地表位移场,为浅层断层滑动和破裂带变形提供了新的约束,有助于研究地震破裂过程和断层生长过程。After a major earthquake,in addition to determining the location and magnitude of the earth-quake,the analysis of the coseismic displacement and deformation patterns near the seismic rupture zone is equally critical,which is crucial for an in-depth understanding of the seismic rupture process,fault behavior,and the relationship between active faults and topography.Although the geodetic techniques for observing the coseismic displacement field of the earth's surface at various spatial and temporal scales are developing rapidly,obtaining a detailed seismic rupture zone and displacement field remains challenging.Current techniques for obtaining these measurements,including Global Navigation Satellite Systems(GNSS),radar or optical remote sensing,and field observations,have their respective limitations regarding observation density,coverage area,measurement dimensions,and operational efficiency.Recently,the widespread adoption and application of high-precision and high-density topographic observation technologies(such as SfM and LiDAR)have enabled geomor-phologists and geologists to capture various Earth surface features with unprecedented spatiotemporal resolution and detail.This has made it possible to map detailed three-dimensional displacement fields.This paper introduces an Iterative Closest Point(ICP)algorithm that uses pre-and post-earthquake topographic point clouds to determine near-field three-dimensional coseismic surface displacements.The main purpose of developing this algorithm is to quickly provide data on the coseismic displacement field near the seismic rupture zone after a major earthquake,compensating for the deficiencies of existing geodetic measurements or field observations.To test the applicability and workflow of the ICP algorithm for obtaining topographic data through aerial photogrammetry in the Sichuan-Yunnan region,we selected two sets of SfM topographic point cloud data from the Jiaoji River fault on the Daliangshan fault zone.By superimposing the coseismic deformation field to simulate t

关 键 词：三维同震位移场 ICP算法 地形点云 地震破裂 活动断层 

分 类 号：P315.2[天文地球—地震学]