汶川Ms8.0级地震的水系响应

The Ms8.0 Wenchuan Earthquake and Co-seismic River Response

2008年5月12日龙门山汶川8.0级地震导致了映秀—北川断裂、彭县—灌县断裂、小鱼洞断裂和擂鼓断裂发生了地表破裂,在平面上显示为两条近于平行的北东向逆冲—走滑型断层,在剖面上显示为叠瓦状。汶川地震的地震破裂和同震变形在瞬间就改变了地形坡度,并导致地貌和河流体系产生相应的变化和调整,记录了整个区域的位移情况,为探索地震与水系之间的关系提供了关键信息。在整合汶川地震所导致的地表破裂、地形和水系变化相关数据的基础上,描述了汶川地震驱动的逆冲作用和右旋走滑作用引发的河道垂向位错和水平位错,标定了汶川地震导致的河道坡折点和河道转折点,刻画了映秀—北川断裂和彭县—灌县断裂和小鱼洞断裂等活动断裂对河床剖面、河道走向、河道分段性和不规则水系样式等方面的控制作用,探讨了汶川地震驱动了隆升作用对河流剖面的影响与调整,建立了汶川地震的水系响应及其识别标志。研究结果表明:汶川地震驱动的构造作用对该区水系的河道走向、河道坡折点、河道流转折点和河床剖面具有明显的控制作用,为重塑龙门山晚新生代构造-地貌-水系演化提供一个范例和定量约束条件。

By comparing the initial analysis of the surface rupture on the Yingxiu-Beichuan fault,Pengxian-Guanxian fault,and Xiaoyudong fault caused by Wenchuan Earthquake,it was suggested that the plane fabric pattern of the surface rupture is consisting of two parallel thrust fault on the surface,linked by the Xiaoyudong fault,and the profile pattern of the rupture is consisting of two imbricated thrust fault in the profile.According to the features of the surface rupture of the Wenchuan earthquake and river response,the responses of channel vertical offsets to thrust faulting and the river lateral responses to the strike-slip faulting driven by the Wenchuan earthquake were described.The co-seismic tectonic effects on vertical channel offsets,lateral channel offsets,such as the Yingxiu-Beichuan fault,the Pengxian-Guanxian fault and the Xiaoyudong fault on the offsetting of river courses,river gradient,drainage pattern,river valley,river profile,strike of the river channel,tectonic diversion of the river channel,tectonic slope-break of the river channel on the Minjiang river,the Jianjiang River,Baishuihe river and Mianyuanhe river were stated.Based on the relationship between the faulting driven by the Wenchuan earthquake and river response,it was concluded that the active tectonic effects on river profile,strike of the river channel,diversion of the river channel,slope-break of the river channel are very obvious.