Paleoseismological Evidence of Large Pre-historical Earthquakes on the Western Haiyuan Fault Near Tianzhu, Gansu Province
作者单位：Laboratoire de TectoniqueInstitut de Physique du Globe4 place Jussieu 75005 ParisFrance Laboratoire Laboratoire de TectoniqueInstitut de Physique du Globe4 place Jussieu 75005 ParisFrance
会议名称：《第四届青藏高原国际学术研讨会》
会议日期：2004年
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]
摘 要：正The Haiyuan fault is a major active left-lateral fault that bounds the Tibetan Plateau to the northeast. Two great earthquakes have ruptured the fault system in the past century: in 1920 （M=8.7） along the eastern Haiyuan fault and in 1927 （M=8-8.3） on a thrust fault system north of the western Haiyuan fault. Studying this active fault has profound implications on the framework of deformation of the TibetanPlateau, and on the mechanics of continental deformation in general. Previous studies have mainly focused on the slip rate of the fault, which remains debated. Paleoseismological investigations on the fault are sparse and mainly in the reach of the 1920 earthquake rupture, or along the eastern half of the Haiyuan fault. The seismic history of the 260-km-long western Haiyuan fault is largely unknown. Despite clear evidence in the field of Holocene activity, this segment of the fault bears no trace of a large earthquake in the past several centuries. It has therefore been reported as a major seismic gap （the ’Tianzhu gap’） with high potential seismic hazard.