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

摘要： 采用新疆维吾尔自治区地震局精度较高的常规地震目录和双差定位目录,对乌鲁木齐地区震源深度的分布特征及与断层的关系进行了研究。结果表明,乌鲁木齐地区的平均震源深度随震级的增加而加深,并形成3个分布层。震源绝大多数分布在上地壳1～35km深度范围内,优势集中在上地壳16～25km深度范围内。平均震源深度的空间分布特征与断层的展布密切相关,乌鲁木齐市附近的3组断裂所夹持的地块震源深度最浅,深度处于17～21km之间,而在周边一些深大断裂上震源深度较深。不同构造部位的震源深度剖面显示,清水河子断裂、齐古断裂、依连哈比尔尕等断裂的断裂面处于无震蠕滑或闭锁状态,地震主要发生在其下的滑脱层中;而在霍尔果斯、西山、二道沟等断裂上,震源深度从滑脱层延伸到断裂面上,反映出断裂未完全闭锁时的弱运动状态,显示这些断裂为新的活动断裂。震源深度的分布还与乌鲁木齐地区复杂的地壳结构有关,地震多分布在低速体之上或低速体和高速体之间的夹层中。

关键词: 震源深度, 地震断层, 新疆乌鲁木齐