汶川地震近区深层井孔-含水层系统水位异常响应研究

Research on abnormal response of groundwater levels in deep wells in the near-field to the Wenchun Earthquake

本文探析了汶川地震近区深层井孔-含水层系统在不受水量交换的影响下地下水位的动态变化特征。结果表明,大地震的发生往往能够引起较大范围内深层井孔-含水层系统地下水位明显的异常变化,地震引起的地下水位异常变化特征比较复杂,具有异常形态变化多样,变化幅度不等,变化空间分布不均一,时间分布多阶段以及随时空分布迁移等特点。同时,认为引起汶川地震震时和震后井孔-含水层系统水位异常的机理主要有两个:地震发生时映秀—北川断裂两侧岩体发生错动,引起沿岩体破裂方向(NE)断层附近含水层的地下水位发生显著的突变现象;地震波的传播作用引起云南一带地下水位发生振荡现象。

Based on the regional tectonic stress of the Wenchuan Earthquake, the groundwater-level dynamic change of the deep borehole-aquifer system without the influence of water quantity is analyzed in this paper. The results show that during seismic gestation, occurrence and development, with the accumulation and release of rock stress-strain, the groundwater-level of the deep borehole-aquifer system can change significantly. The groundwater abnormal response arisen by seismic regional tectonic stress is very intricate. The changing shape of groundwater levels is various and the changing extent is different. The space distribution is unequal and the time distribution has several phases. The change in groundwater levels move with time and space. Two reasons are thought to be responsible for the coseismic and post-seismic groundwater-level response of the deep borehole-aquifer system to the Wenchuan Earthquake. （1） When the earthquake happened, both sides of the Yingxiu-Beichuan rupture moved along different directions. As a result, the aquifer groundwater-level changed abruptly along the rock rupture direction; （2） Another abnormal phenomena is the groundwater-level oscillation arisen by the propagation of the seismic wave.