[H-DS05] 地すべりおよび関連現象

[HDS05-13] Geological structure detection of large-scale deep rock landslide based on seismic ambient noise

*Shenghua Cui¹、Hui Wang¹、Xiangjun Pei¹ (1.State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology)

キーワード：Seismic ambient noise, Sliding surface depth identification, Landslide volume calculation

The occurrence of landslides affects many regions of the world, causing huge economic losses and human casualties, making landslide risk assessment and prediction particularly important. However, it is a very complex task that requires detailed geological information, the geometry of the landslide body, and the physical properties of the geotechnical materials. To achieve these objectives, various methods (detailed geomorphological surveys, geotechnical investigations, local instruments monitoring, InSAR, etc), as well as geophysical techniques, are used. As for detecting internal geological structural units, drilling is a traditional exploration method. but there are many problems, including large costs due to large study areas and difficulties in construction on unstable slopes. So more and more geophysical methods are being applied to large landslide detection. Among them, the seismic ambient noise method can detect the boundary of various material types of landslides based on the sudden change of seismic impedance caused by the change of material type properties. At present, this method is mostly applied to soil landslides, and its applicability to rock landslides still needs to be verified. Here, we innovatively adopted this method to detect the geological structure of a large rock landslide, the Tizicao landslide. More than one hundred single seismic noise monitoring points were arranged on the Tizicao landslide and good quality data were selected for horizontal-vertical spectral ratios calculation. In the prior conditions of the inversion, we use the borehole data and the results of the multi-channel analysis of the surface waves method to minimize the multi-solution of the inversion results. The velocity interpretation model obtained based on the seismic ambient noise method and the electrical resistivity tomography are mutually corrected to obtain a three-dimensional geological model of the Tizicao landslide. The 3D geological model with accurate sliding surface depth combined with the accurate slope surface area obtained from the UAV image was used to calculate the landslide volume on the GIS platform. Our results show that seismic ambient noise is an efficient and nondestructive method that can be applied to characterize and assess the hazard of large deep-seated rock landslides.