龙门山汶川地震特征及构造运动学初析
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摘要
2008年5月12日发生的龙门山汶川地震具有震级巨大、波及面宽、震中成线性展布的特点。根据震后构造地质调查,引发本次地震的断层活动主要表现为幕式斜冲与逆冲,其运动学特征是:断裂具有先走滑后逆冲,总体表现以逆冲运动为主。根据断裂面多期擦痕特征确定,断层活动主要为三期幕式活动,第一期为逆冲走滑,第二期为逆冲冲断,第三期为走滑逆冲。由地震破裂构造确定的主压应力方向为北西-南东方向。
On 12 May,2008,an earthquake occurred in Longmen Mountains,whose main epicenter is located in Wenchuan of Sichuan.This unexpected hazard is characterized by the huge magnitude,wide affected areas,and the linear distribution of the epicenters.Based on the tectonic geological investigation after the earthquake occurred,the faulting activities triggering the huge earthquake consist of two episodic stages.Oblique-thrusting and reverse-thrusting are the two kinematic features,which are composed of the two components of strike-slip and thrusting.Between them,the strike-slipping occurred first followed by the reverse thrusting,and then the reverse thrusting dominates mostly.Analyzing the multi-stage slickensides on the fault surfaces,there are three episodes of faulting activities.The first episode is characterized by the oblique-thrusting,the second episode is reverse-thrusting,and the third one is the strike-slipping.The direction of σ1 which triggered the earthquake is NW-SE.
On 12 May,2008,an earthquake occurred in Longmen Mountains,whose main epicenter is located in Wenchuan of Sichuan.This unexpected hazard is characterized by the huge magnitude,wide affected areas,and the linear distribution of the epicenters.Based on the tectonic geological investigation after the earthquake occurred,the faulting activities triggering the huge earthquake consist of two episodic stages.Oblique-thrusting and reverse-thrusting are the two kinematic features,which are composed of the two components of strike-slip and thrusting.Between them,the strike-slipping occurred first followed by the reverse thrusting,and then the reverse thrusting dominates mostly.Analyzing the multi-stage slickensides on the fault surfaces,there are three episodes of faulting activities.The first episode is characterized by the oblique-thrusting,the second episode is reverse-thrusting,and the third one is the strike-slipping.The direction of σ1 which triggered the earthquake is NW-SE.
引文
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