铅垂断层向错引起的地表重力变化

利用直立长方体组合模型以及坐标旋转理论,对铅垂断层向错引起的重力变化进行数值模拟,分别计算深度为1、5、10km的铅垂断层在单一方向上、两个方向上向错引起的地面重力变化。结果表明,当断层在单一方向产生向错时,以左端点为基点的W1、W2向错引起的地面重力变化场均呈现以断层为轴线的对称分布;以中点为基点的W3向错引起的地面重力变化场构成四象限反对称分布。当断层在两个方向上同时产生向错时,以左端点为基点的W1W2向错引起的地面重力变化场呈现以断层为轴线的对称分布,整体显示W2向错起主导作用;以中点为基点的W2W3向错引起的地面重力变化场呈现非对称分布,整体也显示出W2向错起主导作用,断层附近的扭错现象为W3向错的作用。随着断层深度的增加,断层向错引起的地面重力变化值递减,但影响范围逐渐扩大。

A Gravity Changes Theory of Vertical Fault Disclinations

Simulated fault parameter values are adopted to deduce the earth surface gravity changes with the combination model of vertical rectangular and the coordinate rotation theory. Numerical simulated experiments of gravity change distribution are conducted for the activities of the vertical fault disclination in a single direction and in two directions, respectively, at depths of 1 km, 5 km and 10 km. The conclusions show that the gravitational variation field shows symmetrical distribution when the vertical fault occurs with a disclination of W1 or W2 pattern based on the left point of the fault in a single direction. In addition, it appears that four quadrants show an antisymmetric distribution when a vertical fault occurs with a disclination of W3 pattern based on the midpoint of the fault. The gravitational variations field shows symmetrical distribution when the vertical fault occurs with a disclination of W1W2 pattern based on the left point of the fault. Moreover, the W2 pattern plays an important role. Gravitational variations field presents a symmetrical distribution when the vertical fault occurs with a disclination of W2W3 pattern based on the midpoint of the fault, with an obvious twisting phenomenon that is attributed to the disclination of W3 pattern in the fault vicinity. Overall, it also shows that the W2 pattern plays an important role. The earth surface gravity change is decreasing progressively when the depth of faults is increasing. However the region influenced by the vertical fault disclination is extending.