空间地震动场的相干性研究

Coherency of spatial ground motion field

地震动的空间变化受震源破裂过程、传播途径和场地条件等因素影响,目前地震动场的相干性研究大多是用台阵实测数据,不具有普适性。采用震源位错模型,利用数值方法模拟均匀单一介质随机地震动场的理论地震图,通过对大量计算数据的分析,研究地表地震动场的空间相干性。分析结果表明:数值模拟结果所反应的地震动空间相干性规律与实测数据所反应的规律基本吻合,表明该分析方法和模型的合理性。同时空间地震动场相干性随地震波的传播方向存在各向异性,断层走向是空间地震动场相干性的重要影响因素。该方法是对地震动场相干性具有普适性的一个尝试。

By using dislocation model of seismic source, the theoretical seismogram of random earthquake motion field in homogeneous and single medium was simulated numerically. Spatial coherence of surface earthquake motion field was investigated, based on a great deal of calculated and analysed data. The results show that the laws regarding spatial coherence of ground motion reflected in numerical simulation results basically accord with those reflected in measured data, which indicates that the analysis method and model adopted are reasonable. Besides, anisotropy exists in spatial coherence of ground motion in the propagation direction of seismic wave, and fault strike is an important influencial factor affecting spatial coherence of ground motion.