银川盆地水平运动和地震活动特征分析

摘要

In order to determine the future seismic risk of Yinchuan area,we undertake a comprehensive study of the main faults and tectonic evolution,GPS velocity field,modern seismic activity and hypocenter depth profile of the Yinchuan basin.The results show that the power of the Yinchuan basin is mainly due to the influence of the NW subduction of the Pacific plate and the NE compression of the Qinghai-Tibet plateau,and that the basin is in the environment ofshearing and pulling.The GPS velocity field shows that the velocity in the south of the Yinchuan basin is larger than that in the north.Horizontal tensile deformation and shear deformation during the period of 2009-2015 are reduced compared with that in 1999-2007,but the rate is increasing.According to modern seismic data and hypocenter depth profile,the distribution of the earthquake is mainly near the fault and the focal depth of the earthquake is controlled by the faults,indicating that the fault has a good control of the earthquake.Furthermore,the GPS parallel velocity and small seismicity in the basin have good correlation with the fault activity.The GPS parallel velocity is high,the activity of the small earthquake is intensive and the activity of the fault is strong.%对银川盆地的主要断裂及构造演化、GPS速度场、现代地震活动及其震源深度剖面等进行研究.结果表明,银川盆地受到太平洋板块北西向俯冲和青藏高原北东向挤压作用影响,并处于剪切拉分断陷环境;GPS速度场显示,盆地内断裂南段比北段速率大,2009～2015年的水平拉张变形和剪切变形与1999～2007年相比有所减小,而速率值相对增加;现今地震资料及震源深度剖面显示,地震主要分布在断裂附近,并且地震的震源深度受断裂控制,说明断裂对地震有很好的控制作用;盆地内GPS平行速率和小震活动与断裂活动性具有较好的相关性,GPS平行速率大,小震活动密集,断裂的活动性强.