Isoseismal area and long axis radius based intensity attenuation relationship

The elliptical intensity attenuation model was widely used in our country.This model can well approximate the real isoseismal shape of moderate earthquakes.For strong earthquakes,however,some discrepancies exist between the near field isoseismal and the estimated elliptical model.Because the real isoseismal at near field is more like"track"other than ellipse,and it gradually comes to ellipse in middle-far field,how to find a hybrid model,which can approach both track and ellipse,is an urgent issue.Thus,an isoseismal area and major axis radius based intensity attenuation relationship is proposed in this paper.For confirming its validity,38 strong events,the magnitudes(M s) of which are greater than 6,are selected to construct a strong earthquake intensity attenuation relationship.Result shows that the proposed attenuation relationship can well approximate the real isoseismal shapes.