地震发电机效应诱导的地震电磁场研究

项目名称： 地震发电机效应诱导的地震电磁场研究

项目编号： No.41474038

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 天文学、地球科学

项目作者： 高永新

作者单位： 合肥工业大学

项目金额： 90万元

中文摘要： 导电的地层做切割地球磁场运动产生动生电动势和动生电流，进而产生电磁场的现象被称为地震发电机效应，是产生地震电磁异常的一种重要机制。本项目旨深入认识这一机制诱导的地震电磁场，拟在前期获得的全空间解析解基础上进一步开展如下研究：（1）建立计算水平分层介质中地震诱导电磁场的半解析算法和含不规则界面地层震电波场的有限差分方法，研究含界面地层中地震波和电磁场的耦合特点，阐明同震电磁场与地震波场的关系,揭示提前于地震波到达的辐射电磁波的激发、传播规律；（2）开展地震发电机效应和动电效应产生的地震电磁场的对比研究，理清两种机制各自主导震电转换的条件；（3）分别基于这两种机制对实测地震电磁信号开展正演模拟，分析理论信号与实测信号之间的差异，探讨产生实测电磁信号的合理机制。项目的完成有助于认清地震电磁场的生成机理，可以为实测电磁资料的解释提供理论依据，对今后利用地震电磁场服务于地震预警和防震减灾有重要意义。

中文关键词： 天然地震；地震发电机效应；地震波；电磁场；数值模拟

英文摘要： Motion of the conductive earth's crust across the ambient earth's magnetic field can yield an electromotive force as well as a motional-induction electric current, which then gives rise to electromagnetic (EM) fields. Such a kind of mechanoelectric coupling is referred to as the seismic dynamo effect and has been proposed to be an important mechanism for the generation of the anomalous EM disturbances observed during earthquake events. In order to get an in-depth understanding of the earthquake-induced EM fields arising from such a mechanism, we plan to do the following works on the basis of our preliminary study in which the full-space analytical solutions of the seismoelectric wavefields have been obtained. (1) We will develop a semi-analytical algorithm to calculate the earthquake-induced EM fields in horizontally-layered media and a finite-difference method to simulate the seismoelectric wavefields in complex strata with irregular interfaces. Using the numerical simulators, we will study the properties of the coupling between the seismic and EM waves, reveal the relation between the coseismic EM fields and their corresponding seismic wavefields and investigate the generation and propagation of the EM wave which is radiated by the earthquake source and arrives earlier than the seismic wave. (2) We plan to make comparisons between the earthquake-induced EM field resulting from the seismic dynamo effect and that arising from the electrokinetic effect, and explore the conditions for each mechanism to dominate the seismoelectric conversions.(3) We will make forward simulations of the EM signals observed during actual earthquakes on the basis of the seismic dynamo effect and the electrokinetic effect，make comparisons between the simulated and observed signals in order to find the differences between them and discuss the possible mechanism for the generation of the observed data. The completion of this project can benefit the understanding of the mechniasm of the earthquake-generated EM disturbances, provide theoretical basis for the explanation of the earthquake-generated EM data, and has great importance in the application of the earthquake-generated EM fields to the earthquake early warning and disaster reduction in the future.

英文关键词： earthquake;seismic dynamo effect;seismic wave;electromagnetic field;numerical simulation