2008年3月21日于田7．4级地震的构造背景

Tectonic background of the Ms 7.4 earthquake at Yutian on March 21,2008

2008年3月21日在新疆和田地区于田与策勒县交界处发生7.4级地震。地震发生在塔里木盆地的南边,靠近西昆仑山区边缘的阿尔金地震带。阿尔金断裂带西南端是有三个分支、向西撒开的构造,北面一支分布在硝尔库勒盆地,中间一支就分布在阿什库勒盆地,是这次地震主要的发震断裂构造;南面一支一直延伸到郭扎错盆地,限制了余震的分布范围。地震破裂是以拉张为主兼有走滑运动的倾滑破裂,是阿尔金深断裂左旋扭错的结果,和震源机制解的结果相一致。阿尔金断裂的强烈地震活动,往往伴随有青藏高原周边主要断裂带的大震活动。这次7.4级地震之后的一个多月就发生了四川汶川8级地震,在青藏高原及其边缘和新疆塔里木盆地的西部及帕米尔高原周缘地区是否会引起地震活动的进一步加强,也值得引起注意。

There is a M7.4 earthquake at the boundary of Yutian and Qira County in Hotan Prefecture, Xinjiang,China, on March 21, 2008. The earthquake occurs in the south of Tarim Basin and near the Altyn Tagh earthquake zone at the edge of West Kunlun Mountain. The southwest of Ahyn Tagh earthquake zone displays the structure with three branches, widening towards west. The north branch distributes at the Xiaoerkule Basin. The middle branch, which is the main fault structure of this earthquake, distributes at the Ashikule Basin. The south branch, which limited the extension of aftershock, reaches to Gozha Co Basin. The rupture of this earthquake is left-lateral dislocation Ahyn seismic activity in the Altyn mainly tense deep fault. usually with This goes strike-slip function. It is dip-slip rupture which is the result of is consistent with with the activity in the the focal mechanism solutions. The strong main fault zone around Tibet plateau. A M8.0 earthquake occurs at Wenchuan in Sichuan just after it more than one month. It is noticeable that whether the seismic activity will be strengthened in Tibet plateau or at the edge of it, also in the west of Tarim Basin in Xinjiang and around the Pamir plateau.