Textural criticism on the Biaoshi, Gansu,earthquake in 180 AD

According to historical records, all earthquake catalogs set the epicenter of the 180 A D Biaoshi earthquake to the west of Gaotai County (39.4deg;N, 99.5deg;E) in Gansu Province, and determined its epicentral intensity as Ⅹ and its magnitude as 7 1/2. Result of our textual criticism on historical records indicates that the epicentral location drawn from the existing earthquake catalogs is not definite and amendment should be made. Before the 180 A D earthquake, the Biaoshi town, where the earthquake epicenter should be, was located at Xindunzi town, Minghua District of Sunan County, Gansu Province, and the geographical coordinates of the epicenter should be (39.6deg;N, 99.3deg;E) with a location estimation accuracy of rank 2. After the earthquake, the reconstructed town was located at the present Luotuo town or Caogoujing town. Through careful analysis on historical seismic damage records and comparing the seismic parameters, damage records and affected area of the 180 A D Biaoshi earthquake with that of 8 earthquakes of Mge;6 1/2 during the Han Dynasty and another 9 historical earthquakes occurred nearthe Gaotai County, we finally revised the epicentral intensity of the 180 A D Biaoshi earthquake as Ⅸmdash;Ⅹ, and its magnitude as 7.