Study On The Technology And Index System Of Mountain Towns’Earthquake-Induced Geological Hazard Risk Assessment

A wide range of towns located in133counties (districts) of more than20cities (states) near the Longmen Mountain fault were destroyed diffently by Wenchuan "5.12earthquake. The large number of collapses, landslides, debris flows and other secondary geological disasters induced by earthquake were the main factor caused towns’damage. In this paper, Wenchuan earthquake, this meizoseismal event, was treated as a rare1:1natural experiment. We created the index system of mountain towns’earthquake-induced geological hazard risk assessment though the investigation and study on the type, distribution and control factors of seismic damage. Based on the above, AHP-Fuzzy comprehensive assessment model of mountain towns’ earthquake-induced geological hazard risk assessment was created, and its rationality and applicability was also tested and analysed. Research of the effects and control factors of seismic damage, index system and assessment model of mountain towns’ earthquake-induced geological hazard risk assessment has made some progress.(1) Main types of the earthquake-induced geological hazards threatened mountain towns are shattered mountain bodys (unstable slopes), landslides, collapses, debris flows, barrier lakes, etc.(2) There are three typical types of earthquake damage to towns and hazard control factors of damage, which are respectively earthquake fault effects, the venue destructive effects, geological hazard effects. Earthquake fault effects include earthquake fault dislocation effects and vibration effects; The venue destructive effects include the applification of seismic waves which caused by the surface sediment layer, vibration spectrum effects of foundation and building, local topography effects; Geological hazard effects include instantaneous effects of geological disasters and hazard hysteresis effects. (3) The temporal, spatial and strength characteristics of urban seismic geological disasters exhibited three basic types, which are namely " Tianchi-type "(geological hazard instantaneous type),"Yingxiu-type"(geological hazard hysteresis type),"Beichuan-type"(geological hazard instantaneous-hysteresis mixed type).(4) Indexes of mountain towns’earthquake-induced geological hazard risk assessment include two aspects, which are fault and its kinetic characteristics and urban geological environment, a total of20basic indicators. We also used the method of fuzzy comprehensive evaluation to classify the basic indicator.(5) AHP-Fuzzy comprehensive assessment model of mountain towns’ earthquake-induced geological hazard risk assessment was created.(6) The evalution model was applied to some towns damaged by Wenchuan earthquake, in order to verify its applicability and rationality. The final evaluation model was created by continuous improvement. On April20th, Lushan Richter7.0earthquake occurred, then the model was applied to Longmen, Baosheng, Shuangshi, Taiping and other four towns of Lushan County. Its applicability and rationality was further verified.