走滑断层地表位移动态演化特征研究

在经典走滑断层位移公式基础上引入时间变量, 研究断层运动中地表位移与时间的动态变化关系, 得到走滑断层地表位移时空动态演化公式。 当观测点处于断层近、 中场或者孕震阶段处于孕震中、 晚期时, 地表位移近似正比于时间对数函数。 得到以下结果: ① 走滑断层随时间的位移是不收敛的, 但发散速度十分缓慢。 ② 目前多数GPS水平方向的时间序列良好的线性特征为时间对数函数的局部线性近似。 ③ 在孕震中、 晚期的任意时刻, 断层近、 中场的地表任意一点的位移与其距断层的距离成正比, 即垂直于断层方向的地表位移曲线近似一条直线。 ④ 从震前的某个时刻开始计时, 震前距断层远的站点产生的位移比距断层近的站点产生的位移大; 震后距断层近的站点产生的位移比距断层远的站点产生的位移大。 走滑断层地表位移动态演化公式适用于断层的近中场, 孕震的中晚期, 可为断层地震危险性的判定提供理论支持。

Study on the Dynamic Evolution Characteristics of Surface Displacement for Strike-slip Fault during the Seismogenic Process

Based on the traditianal strike-slip fault displacement formula, the time variable is introduced to study the dynamic relationship between surface displacement and time in motion of strike-slip fault. The dynamic evolution formula of surface displacement of strike-slip fault was obtained. When the fault is on the near-mid field or the seismogenic time is relatively long, the surface motion is approximately proportional to the logarithmic function of time. From the derived formula, we can get: ① The movement of the strike-slip fault over time is divergent, but the divergence rate is very slow; ② The good linear feature of most of the GPS time series is a local linear approximation in the mid-late stage of seismogenic; ③ At any moment in the mid-late stages of the seismogenic, the displacement of any point on the surface of the near-mid field of the fault is proportional to the distance from the fault. That is, the surface displacement curve perpendicular to the fault direction approximates a straight line. ④ Starting observing at a certain moment before the earthquake, the displacement of the station far from the fault before the earthquake is larger than the displacement from the station near the fault; the displacement from the station near the fault is larger than the displacement from the station far from the fault. The dynamic evolution formula of the surface displacement of the strike-slip fault is suitable for the near-mid field of the fault and the mid-late stage of the seismogenic. It can provide theoretical support for the determination of fault seismic hazard.