2004年7月11日西藏Mw62级地震震源破裂过程研究

基于有限断层模型，利用远场体波波形数据研究了2004年7月11日西藏MW62级地震的震源破裂过程.结果表明该地震是一个以倾滑为主的浅源正断层型地震，震源深度为125km，断层面走向152°，倾角44°，平均倾滑角-117°.破裂在震中处成核，然后以28km/s的平均速度向两侧传播，在震中以东偏北5km处达到最大滑动43cm.该地震主张力轴近E W方向，受浅部NNW SSE或N S向裂谷带控制，青藏高原南部的逆冲运动是引发这次地震的直接原因.

Rupture process of the July 11, 2004, Tibet (Mw 6.2) earthquake

The source rupture process of the July 11，2004, Tibet (Mw 62) earthquake is investigated by a finite fault model using far field broadband body wave records. The results show that it is a shallow dip slipping predominant normal fault earthquake, and the hypocentral depth is about 125km. The fault plane has a strike of 152° and a dip of 44°, and the average slip angle is -117°. The rupture nucleates near the hypocenter, then propagates to the two ends of the fault with an average velocity of 28km/s, and the slip reaches to its maximum value of 43cm at about 5km northeast of the epicenter. The main principal \%T\% axis of the fault plane solution shows roughly EW extension, which is controlled by a local rift belt in NNW SSE or nearly NS direction, and the thrust motion of the southern Tibetan plateau towards north is the main mechanical reason of this earthquake.