关键词: 震源深度, 地震断层, 新疆乌鲁木齐

Abstract: We used the catalog of Earthquake Administration of Xinjiang and HYPODD to analyze the characteristics of focal depth and its tectonic significance in Urumqi region,Xinjiang.The results show that the focal depth in Urumqi region increases with the magnitude of earthquake and separates into three layers.For most earthquakes,the focal depth distributes from 1km to 35km,and the predominant depth is from 16km to 25km.The spatial distribution of the average focal depth is correlated with fault;for the earthquakes between the three groups of faults near the Urumqi city,the focal depth is the shallowest,ranging from 17km to 21km,while for the earthquakes occurring on the big and deep faults,the focal depth is deeper.The profile of focal depth in different parts of tectonics shows that most earthquakes didn't occur on the fault planes,but in the detachment layers below them.On the Xishan Fault,the focal depth extends from detachment layer to the fault plane,indicating the fault is in a weak motion state,being not completely blocked.In the regions extruded by Zhunger and Tien Shan,the focal depths extend to the ground surface.The distribution of focal depth is related with the complicated structure of lithosphere in Urumqi region,most earthquakes distribute above the low velocity body or between the low velocity body and high velocity body.

Key words: focal depth, seismic fault, Urumqi Xinjiang