摘要
由人工产生大功率超低频 (SLF)电磁波可以在地面很大范围的许多测点同时测量该信号 ,利用它可以研究地下电阻率结构和空间电磁场 ;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 ,具有广阔的应用前景和发展潜力。在北京等地区的观测表明 ,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。在试验测量期间距测点约 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 ,对产生这些变化的可能的成因机制进行了分析和探讨。
Electromagnetic waves in SLF (super low frequency) frequency band can be transmitted by powered generator using geophysical theory combined with radio physical theory. The artificial signals can be measured in a quite large area on earth surface for investigation of the space electromagnetic field and crust conductivity structure. The method is a useful tool to study electromagnetic anomaly caused by earthquake and to probe the subsurface resources. The experiment study in Beijing and Tianjin indicated that power spectrum density of SLF signal is bigger 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 those by natural signal and is less influenced by disturbance. An earthquake ( M =4 2) occurred near observation site during SLF measurements and coherency between earthquake phenomena and the anomaly of electromagnetic field and apparent resistivity was appeared. It is postulated that the anomaly of electric and magnetic fields and the variation of apparent resistivity were generated due to interaction between regional stress and local electromagnetic source. [
出处
《中国工程科学》
2003年第10期27-33,共7页
Strategic Study of CAE
基金
国家自然科学基金资助项目 ( 4 0 2 740 17)
关键词
超低频/极低频电磁波
电磁异常
电阻率
地震监测
SLF/ELF electromagnetic waves
electromagnetic anomaly
resistivity
earthquake monitoring
