DANGER ASSESSMENT OF EARTHQUAKE-INDUCED GEOLOGICAL DISASTERS IN SHAANXI PROVINCE BASED ON AHP AND GIS
【Abstract】 There are marked differences of geological structure between south and north of Shaanxi Province,which is situated in the middle of China.From north to south,the topography of Shaanxi can be divided into three parts:the Loess Plateau,Weihe Plain and Qinba Mountains.Owing to the special geographical location and the complicated tectonic environment,Shaanxi and its surrounding areas frequently suffer from earthquakes,as well as earthquakeinduced secondary geological disasters.It is no exaggeration to say that Shaanxi suffers from the most serious secondary geological disasters in China.According to statistics,from 1972 to 2012,more than 641 earthquakes with magnitudes above ML3.0 rocked Shaanxi and its neighborhoods.The collapse,landslide,ground crack,ground subsidence,ground collapse and debris flow are the most common types of geological disasters.In 2008,ten days after the Wenchuan earthquake,157 disasters were found in Shaanxi Province which caused incalculable loss to the people’s lives and property.Hence,it is very urgent and necessary to carry out the risk evaluation of earthquakes-induced secondary geological disasters and delimit the risk areas of earthquakes,which has very important practical significance to territory planning,risk management of geological,disaster reduction and prevention and government decision making.In this paper,7 first-grade indexes including lithology,geological structure,topography,rivers,vegetation,rainfall and human activity and 9 second-grade indexes including engineering geological petrofabric,density of the earthquake,earthquake acceleration,gradient,aspect,rivers,vegetation fraction,rainfall and roads were chosen,and the weights of which were determined by building a hierarchy,structuring judgment matrix,hierarchical single arrangement and consistency check through using Analytical Hierarchy Process(AHP).The risk grade region division chart of earthquake-induced secondary geological disasters of Shaanxi will be got from the synthetic evaluations to every index by using GIS spatial analysis function and verified by the survey datas of the earthquake-induced secondary geological disasters sites.The results showed that:(1)the risk levels of earthquake-induced secondary geological disaster in Shaanxi Province can be divided into 4 grades:no dangerous region,low dangerous region,moderate dangerous region and high dangerous region,whose area are 39766.99km2,74284.39km~2,63636.89km~2,27652.87km~2,respectively,in the percentage of 19.37%,36.18%,30.99%and13.47%.(2)The risk grade has a increasing trend from north to south,which means Loess Plateau is low and moderate dangerous region,overall risk of Weihe Plain is lesser,and Qinba Mountains was absolute the high-risk area.More attention should be paid to Qinba Mountains because its high dangerous of geological disasters.(3)On the spatial distribution,the dangerous area distribution has the characteristics of relatively centralized and local differences.(4)Verification results show that the spatial distribution of the disaster sites is consistent with risk grade region division of earthquake-induced geological disasters.86.62%of the disaster sites fell into the risk grade region division chart of earthquake-induced geological disasters,which demonstrated the credibility of this research.
【Key words】 AHP； GIS； earthquake-induced geological disasters； danger assessment； Shaanxi Province；
- 【文献出处】 第四纪研究 ,Quaternary Sciences , 编辑部邮箱 ,2014年02期