基于高精度地基LiDAR技术的活动断层错断地貌研究——以冷龙岭活动断裂带为例

Offset Landform Caused by Active Fault based on High Precision Terrestrial LiDAR Data:A Case Study of the Lenglongling Active Fault Zone

高精度地形测量是活动断裂带定量研究的重要途径,通过对强震活动形成的错断地貌进行测量分析,可以估算断层位移,分析断层破裂的历史过程,揭示强震复发特征。激光雷达测距技术(LiDAR)为研究断层破裂特征提供了重要手段。选取青藏高原东北缘的冷龙岭活动断裂为研究目标,利用地基LiDAR对一些典型错断地貌进行了测量,并就地基LiDAR构建活动断层三维错断地貌的关键技术问题进行了分析。通过对测量得到的点云数据进行点云匹配、镶嵌、植物滤除以及不规则三角网建模处理,得到了0.05m空间分辨率的数字高程模型,划分了地貌单元,识别了断层陡坎与断层错断冲沟等地貌,实现了对断裂微地貌形态的高清晰度三维再现,并据此揭示了沿断裂带存在的多次地震事件,断裂主要表现为左旋走滑活动,并具有微小的倾滑运动分量。

High precision topography measurement is an important approach to quantitative study of active fault. Through the measurement and analysis of the typical offset landform formed by strong earthquakes, we estimated the fault displacement, analyzed the historical process of the fault rupture, and revealed the recurrence feature of the strong earthquakes. Light Detection And Ranging （LiDAR） provides an important method to the study of fault rupture characteristics. We selected the Lenglongling active fault in the NE Tibetan plateau as target, and measured its typical fault offset topography by terrestrial LiDAR. And the key technical problems of the construction of the 3-dimensional fault landform by Li- DAR data are studied and analyzed. For the measured point cloud data, we conducted point cloud matching, mosaic, plant filtering and irregular triangular mesh modeling processing, and then the 0.05 m high-resolution digital elevation model was generated. To identify and divide the geomorphic units, we implemented high resolution 3D reconstruction to the micromorphology and fault geometry of ridge fracture. High precision topogra- phy measurement results of the different offset values reveal that the fault zone have experienced multi-seismic events, and the fault zone mainly behaves left-lateral strike-slip ac- tivity with a slight dip-slip motion component.