Discovery of the Surface Rupture Zone on the South of Helishan in Gaotai,Gansu Province

作     者：Zheng Wenjun Zhang Peizhen Yuan Daoyang Ge Weipeng Liu Jianhui 

作者机构：State Key Laboratory of Earthquake Dynamics Institute of Geology CEA Beijing 100029 China Lanzhou Institute of Seismology China Earthquake Administration Lanzhou 730000 China 

出 版 物：《Earthquake Research in China》 (中国地震研究（英文版）)

年 卷 期：2010年第24卷第1期

页      面：97-105页

学科分类：070801[理学-固体地球物理学] 07[理学] 0708[理学-地球物理学] 

基　　金：supported by the Joint Earthquake Science Foundation (B07007) the Foundation of Base Science of Institute of Geology,CEA (DFIGCEA0607122) the Foundation of State Key Laboratory of Earthquake Dynamics (LED0607) 

主　　题：Surface rupture The Helishan southern margin fault The northern Tibet Gaotai, Gansu 

摘      要：According to a new investigation in the northern Hexi corridor,the remains of two surface rupture zones were discovered on the southern margin fault of the Helishan. One rupture has a length of approximately 7km and the other 10km. The two surface rupture zones might have been produced by the latest earthquake event. On the surface rupture is continuous scarp and free face caused by the rupture. The scarp is about 1 ～ 1. 5m high and on some sites,nearly up to 2m. According to the OSL results,the latest T1 terrace and higher flood plain forming in 3000a B. P. are dislocated by the fault. The above reveals the rupture age to be later than the T1 terrace. However,in the historical data and earthquake catalogue,we didn t find related information about the fault and surface rupture in this area. The 180 A. D. Biaoshi M8. 0 earthquake and the 756 A. D. Zhangye-Jiuquan M7. 0 earthquake are documented in historical data. It is inferred by textual research that the two earthquakes are related to the northern marginal fault of Yumushan in the south of the basin. Due to a lack of reliable evidence,there are still many arguments on this inferred conclusion. Thus we hold that the two surface rupture zones were produced by one of the two large earthquakes or other unrecorded historical event. The research on the activity and surface rupture of this fault can offer valuable information for the tectonic study and strong earthquake risk estimates of this region in the future.