利用地震烈度数据重构历史地震震级和震中位置的方法

采用现代仪器地震记录和烈度资料，我们建立了用于定量估算历史地震震级和震中位置的烈度衰减模型和分析方法，并对我国西南川滇地区的历史和近代地震的震中和震级进行了重新分析.利用20世纪以来该地区十四个有仪器记录的地震（5.9≤M_s≤8.0）及相应的烈度数据，对其烈度-震级-震中距衰减关系进行标定，并建立了用于震中和震级估算的烈度衰减模型.结果表明，当震级一定时，川滇地区烈度随震中距增大而衰减的速率明显小于美国加州地区（～60%）.在衰减模型基础之上，发展了确定震中区域和震级的网格搜索试算方法（GSTSL），并给出了确定震中位置和震级的等值线置信值.采用所建立的分析方法，对1786年康定地震，1850年西昌地震，1913年峨山地震和1970年通海地震进行了分析，给出了更为精确合理的结果.

Reconstruction of magnitudes and epicenter locations of historical earthquakes by using seismic intensity data

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 M_s 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.