高精度无人机航测在2021年玛多7.4级地震地表破裂精细研究中的应用

北京时间2021年5月22日，青海省果洛州玛多县发生MS7.4地震，震中位于巴颜喀拉地块内部，根据震源机制解和野外地表破裂调查确定发震构造为以左旋走滑运动为主的江错断裂。本研究利用大疆Phantom 4 RTK无人机在震后采集大量地表破裂照片，采用集成SfM（Structure from Motion）算法的PhotoScan软件处理获得高分辨率DEM和正射影像，同时结合野外实地考察对研究区地表破裂的分布特征及断错地貌类型进行详细解译。利用基于MATLAB语言开发的位移测量软件LaDiCaoz，限定玛多地震在研究区产生的左旋走滑位移约为0.4 m。地表破裂精细化解译显示，在左旋右阶阶区发育小规模的挤压鼓包和里德尔共轭剪切破裂，在左旋左阶阶区发育走向为N40°～50°E，宽度达数十厘米的张裂缝带，指示发震构造的左旋走滑性质。本研究为震后基于无人机摄影测量技术快速提取地表破裂的定量参数和进行地表破裂精细化研究提供了可行、高效和科学的技术方法。

Application of High-precision UAV Aerial Survey in the Detailed Study of Surface Rupture of Maduo MS7.4 Earthquake in 2021

On May 22, 2021 (Beijing time), an M_s 7.4 earthquake occurred in Maduo county, Guoluo prefecture, Qinghai province. The epicenter was located in the Bayan Har Block, and the seismogenic structure was determined to be Jiangcuo fault with left-lateral strike-slip movement based on the focal mechanism solution and field investigation of surface rupture. In this study, the DJI Phantom 4 RTK UAV was used to collect a large number of photos of the surface rupture after the earthquake, and PhotoScan software integrated with the Structure from Motion (SfM) algorithm was used to obtain DEM and ortho images with high resolution. At the same time, combined with field investigation, the distribution characteristics of surface rupture and the types of displaced landform in the study area were interpreted in detail. Using the graphical dislocation measurement software LaDiCaoz developed based on Matlab, the left-lateral strike-slip displacement of Maduo earthquake in the study area is limited to 0.4 m. The results of the detailed interpretation of surface fractures show that there are small-scale compressional swelling and Riedel conjugate shear cracks in the left-lateral right-stepping zone and tensional fracture zones with a strike of N40°～50°E and a width of tens of centimeters in the sinistral left-steeping zone, indicating the sinistral strike-slip nature of the seismogenic fault. This study provides a feasible, efficient, and scientific-technical method for the rapid extraction of quantitative parameters of surface rupture and the detailed analysis of surface rupture based on UAV photogrammetry technology after large earthquakes.