| The Li County is located in the north-western Sichuan Basin, upper reaches of Minjiang River, is a sensitive area of unstable slopes. According to the survey maked by Sichuan Geological Survey Institute in 2007, the county has 358 points of geological disasters, in which 74 points of landslides, 105 points of unstable slopes, 65 points of landslides and 114 points of debris flows. After the 5.12 Wenchuan earthquake, landslides and instability slopes throughout the county added 41 points, collapse added 60 points, debris flows added 6 points. In order to identify environment background ,in which the geological disasters of li country after the earthquake occurred, to find out the conditions for the formation of geological disasters and the impact of factors, which determine the risk of geological disasters after the earthquake, an effective geologieal disaster risk assessment needs being ensured to prevent hazards and reduce its economic loss, a complete model for hazards assessment also must be quickly searched for, In this paper, reasonable discussions have been done into this research area, and major outcome has been obtained as follows:1,This paper has proposed the clear geological disaster risk assessment method mentalily of Li country after the earthquack, aslo survey of field - collection of information– date analysis– factor quantification– model evaluation– obtains the result– result analysis, and has completed the entire geological disaster risk appraisal system of Li country after the earthquack.2,This paper anaysed the regional environment background of geological disasters, and spatial distribution of geological disasters, characteristics of geological hazards before and after the earthquack were compared, studied the formation of geological disasters in the conditions and influencing factors after the earthquack, and based which, select elevation, lithology, terrain slope, the intensity of earthquakes and water system as the main-sensitive factors of risk assessment of geological disasters of Li country after the earthquack.3,This paper anaysed the basic characteristics and causes of disaster of typical diasters of Li country after the earthquack, qualitatived assessment of the danger of geological disasters, and understood the characteristics of disaster of typical diasters of Li country after the earthquack from a single point disaster.4,This paper proposed the geology disaster of Li country after the earthquack risk appraisal's way, namely the appraisal's way was this kind of flow of"analysis of characteristics of geological hazards– anysis of the causes of the mechanism– sensitive factorial analysis and the qualitative analysis inference– mathematical model superimposition analysis– quality synthetic evaluation", and has annotated this flow well with Arcview, has botatined the achievement chart finally. The concrete steps are: using the sensitive factor analysis, and the factor quantitative, by the use of ARCVIEW software to establish the evaluation factor graphics database (l: 5 million), and attribute to each factor grid (20m×20m) form, extracted the attribute data of the factor of the location of geohazard and expressed as grid data, calculated the relative frequency of geohazard and the attributes of each grid, and calculated the number of disasters in the points per square kilometer, showed the sensitivity of the properties type of each factor, on the basis of the graphics database of each evaluation factor , applied the GIS analysis to make the numbers of layers of multi-storey space numerically and normalized, that is, by 1, 2, 3 and 4, respectively, numerical rating assigned to each grid by the calculation factor of the overlay tool in ARCVIEW Overlay , and calculated for each grid cell to obtain the average of the values divided by the risk classification method, the total is divided into high, medium and low-risk zone, and its criteria for the classification as follows: 13 to 19 for high risk zone, 12 to 13 for dangerous areas, 6 to 11 identified as low-risk areas, and red, yellow and green three colors, respectively, showed the danger of geohazard in the high, medium and low, by which has gained the map of geohazard evaluation for the Li County after the earthquake.5,This paper compared the geological hazard zonation results of Li country after the earthquack with the control division before the earthquack, and Reached the function of 5.12 Wenchuan earthquake on the danger of geological disasters of Li country after the 5.12 Wenchuan earthquack.
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