基于因子分析法的地震次生灾害影响因素研究

Influential factor analysis of earthquake secondary hazard based on factor analysis method

采用多元统计分析方法,对"5·12"汶川大地震灾害发育最密集的龙门山地区雎水河、茶坪河、绵远河、石亭江4流域地震次生灾害的统计数据进行了分析。通过探索性因子分析方法,将影响地震次生灾害发育的10个影响因素简化为5个因子,即断层距、高程与地质结构因子、距离因子、方位因子、坡度因子和相对高程因子。通过对这些因子的权重分析验证了龙门山地区灾害发育的重要特性:即区域地震次生灾害沿发震断裂的"带状"分布且具有明显的上下盘效应。同时,分析结果也表明在强震区域,灾害的发育更受宏观要素如断层距、绝对高程等作用控制,因此在断裂带及潜在震源地区的地震次生灾害易发程度判定中,应综合考虑断裂带及海拔高程的影响,将具有有利岩性及结构的边坡也纳入评估范围。

The multivariate statistical analysis is applied to study the secondary geological disasters in four river basins of Suishui River,Chaping River,Mianyuan River and Shitingjiang River in Longmenshan area where the geological disasters were the densest in 5. 12 Wenchuan Earthquake. Through Exploratory Factor Analysis,the ten factors that influence the development of earthquake secondary disaster have been reduced to five factors as the fault distance,elevation and geologic structure factor,the distance factor,the direction factor,the gradient factor and the relative elevation factor. The weight analysis of these factors explains the important distribution characters of the earthquake secondary hazard in Longmenshan area,that the hazards are in a zonal distribution along the seismic fracture and has a significant hanging / foot wall effect. Meanwhile,the statistical analysis results indicate that the development of the hazard is more easily to be affected by macroscopic factors such as fault distance and absolute elevation in strong earthquake areas,so in the susceptibility analysis of secondary geological hazard in the area near active fault and the potential earthquake source area,even the slope with favorable tectonics and geological structure should be brought into in the evaluation range by comprehensively considering the influence of the fault distance and absolute elevation.