Reconstruction of magnitudes and epicenter locations of historical earthquakes by using seismic intensity data
利用地震烈度数据重构历史地震震级和震中位置的方法

We have estabished an intensity attenuation relationship and analysis method between the epicentrers and magnitudes of historical earthquakes with modern instrumental records and intensity data. With this technique, we have focused our study on Southwest China where there are a lot of moderate or large historical and modern earthquakes occurred since last a few centuries. First, fourteen earthquakes with modern instrumental records with magnitude ranging from Ms 5.9 to 8.0 in this region are used to develop an intensity-magnitude-epicentral distance attenuation relationship. The intensity attenuation relation predicts that, with the same earthquake magnitude, the intensity decreases with distance in this region at a rate about 60% of predicted by the California intensity attenuation model. Based on the intensity attenuation model, we have proposed the Grid Searching of Trial Source Location (GSTSL) method for estimating earthquake magnitudes and bounding epicentral regions, and the confidence value of contours are also calculated. Finally, in order to test the technical strategy we have developed in estimating historical earthquake magnitude and bounding epicentrers. Four typical earthquakes are used in our analysis. They are the 1786 KangDing event, 1850 Xichang event, 1913 Eshan event and 1970 TongHai event.