Abstract:An M8.0 great earthquake occurred between Wudu and Wenxian,Longnan district,on July 1,1879(May 12,Guangxu 5,Qing Dynasty).The complex geological structure,traffic inconvenience,and lack of systematic data and regional field trips have led to speculations and discussions about the true conditions of the earthquake for half a century.However,many questions remain.Comparative analysis of more than 20 studies concerning this earthquake has revealed that the macroscopic epicenter of the earthquake is located in Qiaotou and Tunzhai(now Tianchi township)along the Yangtang River.Moreover,the magistoseismic area extended to Guoyuan Township in Jiuzhaigou County,Sichuan province,and Liangshui and Shimen Township in Wudu,Gansu province.