2017年临安4.2级地震震中附近断裂活动性研究

Study on the Activity of Faults Near the Epicenter of the Lin'an M4.2 Earthquake in 2017

2017年4月12日浙江临安发生了4.2级地震,在震中附近范围(35～50 km)内,主要发育3条断裂,分别为马金—乌镇断裂、湖州—临安断裂和昌化—普陀断裂,通过对这3条断裂开展野外地质调查、断层泥年龄样品测试等手段得出:北东向的马金—乌镇断裂、湖州—临安断裂均被近东西向的昌化—普陀为界分南北为两段,其中,马金—乌镇断裂北段以正断为主,南段以逆断为主,两段活动时代均为中更新世早期;湖州—临安断裂南北两段均以逆断为主,北段活动时代为中更新世早期,南段活动时代为前第四纪。昌化—普陀断裂以走滑活动为主,自西向东分为西、中、东三段,活动时代自西向东逐渐减弱,东段为前第四纪断裂,中西段为中更新世断裂。

Within the vicinity of the epicenter (35~50 km) of Lin'an M4.2 earthquake occurred on April 12, 2017 in Zhejiang,there are three faults, namely Majin-Wuzhen fault,Huzhou-Lin'an fault and Changhua-Putuo fault. Through the field geological survey of these three faults and the dating of fault mud samples,it is concluded that the NE-trending Majin-Wuzhen fault and the Huzhou-Lin'an fault are divided into the north and south segments by the near-EW-oriented Changhua-Putuo fault. The northern section of the Majin-Wuzhen fault is dominated by normal fault,the southern section is dominated by thrust faults,and the active periods of two section is the early Middle Pleistocene. The two sections of the Huzhou-Lin'an fault are both thrust faults,and the activity era of the northern part is the early Middle Pleistocene,the activity era of the southern part is the pre-Quaternary. The Changhua-Putuo fault is mainly composed of the strike-slip fault, which is divided into the west, middle and east segments from west to east. The activity age gradually weakens from west to east. The eastern segment is the pre-Quaternary fault, and the middle and western segments are the Middle Pleistocene fault.