中文摘要：

实地调查发现,2008年10月6日的西藏当雄Ms6.6级地震的宏观震中位于近南 北向的亚东-谷露裂谷中羊易盆地的北部。调查结果显示,此次地震的震中烈度 可达Ⅸ度,极震区烈度为Ⅷ度,其宏观震中位置、极震区范围、主要余震分布等 都明显受到羊易地堑西侧主边界断裂的控制。地表观察和震源机制解结果一致 表明,该强震活动的直接原因是藏南近东西向伸展变形作用诱发羊易地堑主边界 断裂发生正断层活动,而近期青藏高原及其周边强震活动相对频繁的特点很可能 与四川汶川Ms8.0级大地震所引发的区域应力场调整过程密切相关。

英文摘要：

Field survey shows that the macro-epicenter of October 6, 2008 Ms 6.6 Damxung earthquake is located at northern Yangyi graben in the north section of the Yadong-Gulu rift. The maximum intensity of the Damxung earthquake is IX degree and lies at Yangyi village （29-43.3＇N;90°23.6＇E）. The main boundary normal fault of Yangyi graben is NNE-trending, dipping to east and located at west side of Yangyi basin. It is main seismogenic tectonics on the Damxung earthquake that control the site of macroepicenter, pattern of the iso-seismal contours, distribution of meizoseismal region and aftershocks. The field observation and focal mechanism solutions from HRV and NEIC indicate that the Damxung earthquake of October 6, 2008 occurred as a result of normal faulting along the western boundary fault ofYangyi graben. The normal faulting that caused the earthquake is predominantly east-west oriented extensional deformation that is distributed in southern Tibet and ultimately arises from the convergence of the India plate northwards with respect to the Eurasia plate. Recently, the frequent strong earthquake activity occurred around Qinghai-Xizang plateau as a result of the regional stress field adjustment after the Ms8.0 Wenchuan earthquake.