Based On Gis In Earthquake Geological Hazard Assessment Study

The earthquake triggers a large number of geological disaster(landslide, rockfall and so on) which caused tremendous damage and loss in recent years. It is necessory to evaluate the geological disaster hazard to alarm the dangrous, and keep people away from the hazzrd area or take some measures, which to reduce the harm caused by geological disasters.Environment conditions are relative to geological disaster, which are the material basis of geological disaster. Based on the geological disaster distribution character, this paper use frequency analysis method to analyse the spatial relationship between them. Using spatial analysis and graphical modeling function of ArcGIS software to evaluate the geological disaster susceptibility and hazard assessment. Basee on GIS make a workflow about data acquisition, correlation analysis, evaluation model and zoning issues.The types of geological disaster caused by earthquake including landsldie and rockfall mainly, this paper take them as geological disaster to study the geological disaster hazard. It conatins the following part:conditioning factors extraction and analysis. Take wenchuan district which attacked heavily during the "5.12" Wenchuan earthquake as study area. Based on the geological disaster investigation, built the geological disaster inventory,1:50000 DEM, remote sensing images, lithological map, and other basic geographic information data. According to the spatial distribution of geological disaster character, this paper combine with statistical correlation curve and select the conditioning factors with strong power and low redundancy as the geological disaster hazard assessment factors. After spatializing them, build up a spatial database for geological hazard assessment finally.Goelogical disaster susceptibility analysis. First review the geological disaster assessment methods and recent development both domestic and abroad. then. set up two models based on GIS. assess the susceptibility of the two methods, and make the susceptibility map.Earthquake induced geological hazard assessment and analysis. geological disaster not only associate with earthquakes, but also related with rainfall, human activities. With statistical method to analyse those triggering factors'relationship with geological disasters, then establish the weighd based on information theory. Give the zoning of geological disaster hazard and mapping the area.On the above contents, this study get achieved the following result: It based on spatial distribution of geological hazards and characteristics, statistical analysis of geological environmental conditions of each factor and the correlation of geological disasters. The main geological environment between high incidence of geological disasters factors as:elevation between 1.2～2.4km, slope between 45°～60°, relief amplitude between 0.4～0.5km, Phyllite and magmatic rocks have more geological disasters.Compare between the susceptibility model, finding that:the information model is simple and easy to evaluate the weight of those factors, while the logistic regression model has the ability to select factorsis with complicated process. However, the later model has higher accuracy.The susceptibility result indicates that:the most susceptibility class covered 8.9%, this area contains hard proterozoic granite lithology, structural development, terrain cutting strongly, high mountains and steep slopes, and frequent human engineering activities, which caused high geological disasters density. The median class covered 16%, this group filled with Silurian Maoxian phyllite, due to the slope by the road development caused a large number of effective free surface. The normal class covered 19% and low with 22.2%, whoes groups are far away from rivers, roads and low topographic relief. The extremely low class covered 33.9%, whose group including Wolong Nature Reserve, with Complete the geologic structure, mainly Triassic sandstone Xujiahe shale, steep terrain but little human settlement, and low-intensity of the population density, economic activities and human engineering. So we have to strengthen the environment protection and safety of highset susceptibility area.Select the seismic intensity, rainfall and human activity as the Disastrous factors for Hazard assessment. Statistics of the three factors'spatial distribution with disasters, and their impact from macro perspective. Based on the susceptibility division, trying to analyze the earthquake hazard distribution. The results showed that:the most dangerous area located at junction of Minjiang river and Second river, thehazard area has good correspondence with the susceptibility division.