Abstract: A massive earthquake happened on 14 Nov at 09:26:18 UTC along a NWW slip fault belonging to the western part of East Kunlun Fault (EKF) zone. The fault is clearly visible on satellite images (ETM 十 and ASTER). The fault that is along the northern bank of the valley in NW W direction, it is south edge fault of AlkMountain with typical faulting geomorphology. EKF is indeed an active fault likely to host major earthquake (Ms≥8). In the view of the dynamic background, the southern wall of the fault is the active part and the frac"turing progressed from west to east and the source of the earthquake is shallow. Therefore the shock was quicklydiminished in the north and west direction from the epicenter where Qiemo and Ruoqiang County of Xinjiang notfar away from the earthquake experience rather light shock, while the shock in east Geermu of Qinghai Provinceand south direction was much stronger and extended farther. According to the analysis of the dynamic back-ground of QinghaiTibet Plateau active tectonics and the earthquake parameters, this earthquake in the westernpart of EKF was the result of left lateral rotation caused by the north east block of QinghaiTibet Plateaut escap-ing to the east and related to the clockwise rotation of the block.

Key words: East Kunlun fault, Eart hquake, Qinghai Tibet plateau, Tectonic background