Abstract: In this paper, the study area is restricted area of similar topography and seismogenic structure in Southwest China. Taking earthquakes above M6.0 in the recent 100 years as the research object, and finally through analyzing the statistical data, we draw the conclusion that the traditional intensity attenuation elliptical model can not be applied to strong earthquakes above M7.0. Meanwhile, based on the analysis of the relation between intensity area and magnitude, of the relation between rupture length and magnitude, and of the buffer area. We present a fault distance model more applicable to the strong seismic intensity attenuation law. Through the comparison of area statistical relationship and actual intensity distribution, we also obtain a more reasonable intensity attenuation model applied to strong earthquakes. Based on the intensity attenuation model, combined with ArcGIS secondary development, we developed a control software to be used in drawing isoseismal quickly and can help a lot in fast aftershock assessment and earthquake emergency drill.

Key words: Earthquake intensity attenuation, Elliptical model, Fault distance model, Southwest China