岷江上游水系对龙门山断裂带右旋走滑作用的响应

Water System Responding to the Dextral Strike-slipping of the Longmenshan Fault Zone in the Upper Min River Basin

汶川8.0级特大地震是岷江上游流域最新一次区域构造活动,在此次地震中,岷江河道因北川-映秀断裂北西盘的右旋走滑作用而被水平错动0.8±0.2 m,岷江河道南西方向的河流阶地也被同步位错0.6±0.1 m。切过龙门山主干断裂的岷江上游干、支流水系因若干次历史地震驱动的走滑作用而发生同步弯曲。根据水系水平扭错量和岷江干、支流初始形成时间计算可知,穿越岷江支流河道的汶川-茂县断裂右旋走滑速率为1～1.4 mm/a,切过岷江干流河道的北川-映秀断裂和彭县-灌县断裂右旋滑动速率分别为0.94 mm/a和0.71 mm/a。计算结果表明,龙门山各主干断裂右旋走滑作用有自北西向南东减弱的趋势。

The Wenchuan Ms8.0 earthquake was the latest regional tectonic activity in the upper Min River basin. The horizontal displacement of Min River channel reached 0. 8 -＋ 0. 2 m for dextral strike slip movement of Beichuan - Yingxiu fault, and the synchronous displacement of the river terrace in the southwest side of Min River channel reaches 0. 6 -＋ 0. 1 m. The horizontal movement of the main and tributary of Min River were caused by the strike slipping in historical earthquakes. The dextral strike-slip rate of faults was calculated according to the horizontal slip amount and initial formation time of water system. The strike-slip rate of Wenehan - Maoxian fault is 1 - 1.4 mm/a, the strike-slip rate of Beichuan - Yingxiu fault is 0.94mrn/a, the strike-slip rate of Pengxian - Guanxian fault is 0.71 mm/a. The intensity of dextral strike slipping of main faults in the Longmen Mountain were decreased from northwest to southeast.