Quantitative Assessment And Zonation Of Regional Crustal Stability In Northwest Yunnan

Northwest Yunnan is a situated in the zone of three geological tectonic units bounded by Yangtze Platfonn on-east, Garze fold system, and Shangjiang fold system on-west and southwest. These three blocks caused the region to form a zone with intense neotectonic movement, frequent destructive earthquakes. And Northwest Yunnan is a important economic development and tour area. So, it has a important signification that evaluating the crustal stability of Northwest Yunnan not only can to forecast evolutive trend of the geological disaster in the future but also reduce and prevent these disasters. And it can play a important role to keeping substainble development of Yunnan Economy. The neotectonic movement and seism of Northwest Yunnan have the characteristics of high rate of deformation, many active fault, long active time, new active age, big magnitude and frequent activity. So the crustal stability of Northwest Yunnan is determined dominatingly by the active fault and seism. On the basis of geological, seism, active fault and geophysical parameters, Northwest Yunnan is divided into 10 subzones. And the crustal stability is classified as relative stable, relative sub-stable ,and relative unstable. Then the factors of dominating regional crusta] stability are transformed into numerical values, and the subjective function of numerical value of every factor is established. Finally by using comprehensive fuzzy mathematics method, crustal stability evaluate of Northwest Yunnan is accomplished. Based on stable analysis and fuzzy comprehensive evaluation, the stable grade of each subzone of Northwest Yunnan is determined.