基于GPS资料分析银川盆地地壳运动特征
Study of Crustal Movement Features in Yinchuan Basin Based on GPS Data

利用银川盆地及周边地区1999—2007年的GPS数据，研究了该区域现今地壳水平速度场特征，根据区域地壳主应变率、面膨胀率及最大剪应变率的空间变化以及小震分布特征，结合该地区的地质构造背景，对黄河断裂的南北段差异特征及盆地构造动力和地震危险性分析研究，结果表明：研究区内GPS测站主要运移方向为E-SE向。贺兰山东麓断裂和黄河断裂北段以拉张兼走滑运动为主，而黄河断裂南段以走滑运动为主，盆地整体处于剪切拉分断陷环境；银川盆地比周围块体的主应变率大，最大主应变方向为NW向，以张应变为主，结合面膨胀率和最大剪应变率也都显示盆地内存在较强的拉张和剪切变形，盆地内地震主要分布在南部地区；主应变率、面膨胀率、最大剪应变率和小震活动性均说明黄河断裂南段比北段活动性强；银川盆地地壳变形程度高，而周边稳定块体变形弱，黄河断裂和贺兰山东麓断裂分别位于应变强弱变化的东、西边界上，断裂具有较强的应变积累，表现出较高程度的地震危险性。
Using GPS data for the Yinchuan Basin and adjacent regions, in this paper, we describe the characteristics of the current crustal horizontal movement. We investigated the tectonic dynamics and seismic risk in the Yinchuan Basin by analyzing the spatial distribution characteristics of the principal strain rate, surface expansion rate, maximum shear strain rate, and small earthquakes. The results show that the main movement of the eastern piedmont fault of Helanshan and the northern section of the Yellow River fault is extensional strike-slip, whereas the southern section of the Yellow River fault is dominated by strike-slip movement. The principal strain rate of the Yinchuan Basin is higher than that of the surrounding blocks. The surface expansion and maximum shear strain rates in the basin also show strong tensile and shear deformations. The Yellow River fault and the eastern piedmont fault of Helanshan show strong strain accumulation, which indicates a relatively strong seismic risk.