Abstract: Previous studies suggested that the Kuqa, Xinjiang M7.4 earthquake of 1949 is associated with the NEE trending Qiulitage Fault of the active tectonic zone at the southern foot of the Tianshan Mountain. Recently we have made a more detailed analysis of the seismotectonic setting of this event based on new data and results of crustal seismic sounding, petroleum geology, and research of active faults. Our work indicates that the underthrusting of the Tarim block beneath the Tianshan, as well as faulted block uplift and lateral overthrusting and spreading of the upper crust of Tianshan have given rise to the development of the Kuqa basin and thrust-fold system along the southern margin of the Tianshan Mountain. All these are thin-skinned structures developed in the sedimentary cover. The NE-trending Kuqa-Yixi No.1 Well Fault is an important transfer fault in the Kuqa basin, which is located in the NE-trending Urumqi-Kuqa-Keping tectonic zone. The results of seismological research on the M7.4 earthquake indicate that the earthquake bears no relation to the Qiulitage Fault, but is related to the Kuqa-Yixi No.1 Well Fault.

Key words: intracontinental underthrust, thrust-fold system, thin-skinned structure, Kuqa, Xinjiang

摘要： 前人研究认为,库车1949年7.4级地震主要与天山南麓活动构造带的NEE向秋立塔格断裂有关。最近笔者根据深地震地壳测深、石油地质及活断裂等研究的新成果,对这次地震的构造条件进行了较深入的分析。塔里木陆块向天山俯冲,天山上地壳被挤压块断隆升并侧向推覆扩展,于天山南缘形成库车盆地及由秋立塔格等一系列逆断裂组成的逆断-褶皱系,这是发育于沉积盖层的薄皮构造。NE向库车-依西1井断裂是库车盆地构造中重要的传递断裂,位于NE向的乌鲁木齐-库车-柯坪构造带中。有关7.4级地震的地震学研究结果与秋立塔格断裂完全不符,而与库车-依西1井断裂基本一致。

关键词: 陆内俯冲, 逆断-褶皱系, 薄皮构造, 新疆库车