人工源超低频电磁波技术及在首都圈地区的测量研究

ARTIFICIAL SLF METHOD AND THE EXPERIMENTAL STUDY FOR EARTHQUAKE MONITORING IN BEIJING AREA

超低频 (SLF)电磁波技术利用地球物理和无线电物理相结合的原理 ,由人工产生大功率电磁波信号。在地面很大范围的许多测点同时测量该信号 ,可研究空间电磁场和地下电阻率结构 ,研究地震等引起的电磁场异常变化 ,探测地壳结构和地下资源。在首都圈地区的观测表明 ,SLF信号的功率谱密度超过天然场源信号数倍以上 ,所得到的视电阻率数据精度远高于天然源方法 ,并有长时间的稳定性。在测量期间距测点约 12 0km发生的迁安 4 .2级地震与观测的电磁场异常和视电阻率的变化有较好的对应性 ,并对产生这些变化的可能的成因机制进行了探讨 ,推测它们是区域应力场和震源区局部构造综合作用的结果。

The technique of electromagnetic waves in SLF (Super Low Frequency) frequency band can be investigated in the light of geophysical theory combined with radio-physical theory. The artificial signals can be measured in a quite large area on the earth surface to investigate the space electromagnetic field and crust conductivity structure. It is a useful technique for monitoring electromagnetic anomaly caused by earthquake and for probing the subsurface resources. The experimental studies in Beijing and Tianjin showed that the power spectrum density of SLF signal is larger than those of natural electromagnetic signal by several times even in the industry noisy area. The apparent resistivity obtained by SLF method has much smaller error bar than that by natural signal and is less influenced by disturbances. An earthquake (M=4.2) occurred some 120 km away from the Baodi observation site during SLF measurements indicates that the earthquake development and the anomaly of electromagnetic field and apparent resistivity are well correspondent. It is postulated that the anomaly of electric and magnetic fields and apparent resistivity were caused by interaction between regional stress and local electromagnetic source.