EARLY IDENTIFICATION AND ANALYSIS OF EARTHQUAKE AND GEOLOGICAL HAZARDS IN JIUZHAIGOU

Due to the complex topographic conditions and dense vegetation development in Jiuzhaigou region, it is difficult for the traditional manual geological disaster investigation methods to achieve a detailed investigation in a short time. Airborne LiDAR technology has the technical advantage of being able to penetrate through plant gaps and detect microscopic damage to geological objects. InSAR technology has the technical advantage of detecting deformation and damage of geological bodies from macroscopic perspective. Therefore, the two technologies are combined to assist in field verification. By building a macro-to micro-scale geohazard investigation model, it can reduce the workload of manual investigation, improve the identification of potential hazards, and improve the efficiency of geohazard investigation.Based on the above, an internationally advanced high-performance LiDAR scanner was used in this study to achieve the objective of acquiring high-density laser point clouds within 230km² of the study area. High-accuracy digital elevation model(DEM)data of the study area was obtained through a combination of data pre-processing, point cloud denoising, automatic classification and manual vegetation classification operations. The DEM data did not do microtopography removal, but instead retained the microtopography for disaster hazard identification. Based on the data, a three-dimensional interpretation environment was set up. The identification of major geological hazards under the vegetation was carried out by combining the DEM-derived results, optical remote sensing data and the results of previous geological hazard investigations. Meanwhile, the surface deformation monitoring of 230km² in the study area was carried out based on ALOS-2 L-band data and Sentinel-1 data and data processing operations. The integration and interpretation of the airborne LiDAR survey results, the InSAR results and the optical remote sensing image results, enhanced the field verification work, and the field investigation of the difficult hidden hazards, which helped further enrich and optimize the practical effect of the technology system. Ultimately, the identification of geological hazards in the study area was completed. The study demonstrated that the multi-source remote sensing technologies such as airborne LiDAR and InSAR can significantly increase the accuracy and efficiency of geohazard investigation, as well as effectively solve the problem of identifying geohazard hazards in complex terrain and high vegetation cover areas.