50-250Hz 极低频范围内的地震电磁现象研究

采用基于地形学网格划分的时域FDTD 方法来研究地震期间（震前和震期）的极低频电磁现象。由于计算能力的限制，这里主要关注的频率是50-250Hz。为了精确的仿真地震电磁环境，研究过程中引入了地形学信息和天然电磁噪声（闪电）。在仿真中，通过对震区地震电磁激发，我们设置了多个不同的观测点来观测电磁波的传播并进行比较。同时，电离层异常现象也被考虑在仿真过程中。我们的仿真结果证明了在震期电磁波存在传播异常现象，这也证明了之前研究人员所观测到的数据的正确性。最后，我们总结了地震期间的电磁传播异常现象的初步规律。

Study of Seismic Electromagnetic Phenomena in the ELFRange 50-250Hz

Seismic electromagnetic (EM) phenomena in the extremely low frequency (ELF) range prior to or duringearthquakes are studied using the geodesic finite difference time-domain (FDTD) algorithm. Different from our previous studies,in this work the interested frequency range is extended to 100-500Hz. In order to accurately simulate the earthquake EMenvironment, geological information and natural EM noises are introduced. By simulating seismic EM eruptions in the earthquakezone, we have observed and recorded the EM wave propagation in different stations and have compared the results. The effects ofionospheric anomalies on the observations are also discussed. Our simulation results of the ELF wave propagation have shownthe propagation anomalies, and have proved the observed results by the earthquake researchers. We have summarized, finally, thegeneral rules of seismic EM phenomena in the specific frequency range.