Disaster characteristics of Huihuipu earthquake in 1785 in Yumen,Gansu Province,and Discussion on Its Seismogenic Structure

According to the detail textual research of the historical earthquake record and field investigation on Huihuipu earthquake in 1785 in Yumen city,Gansu province.It is found that the serious disaster area situated in Huoshaogou,between Huihuipu and Chijinpu.The magnitude of this earthquake is M63/4,and its epicenter intensity is about IX.Tectonically,the area lies in Jiuxi baisin,which is in western segment of Hexi Corridor.There are several Holocene faults developed in this area,such as Xinminpu fault、Yinwashan fault and Yumen fault,and so on.Most of them are reverse faults.Among them,the position and strike of Xinminpu fault are most consistent with the orientation of isoseismal long-axis of Huiningpu earthquake.And parts of deformation vestiges are still protected up to present.As analysing above,we consider that Xinminpu fault and Yinwashan fault is the seismogenic structure of Huihuipu earthquake in 1785.