地震预测人工源极低频电磁技术(CSELF)是一种新技术,大功率人工源信号在"波导"中传播,可覆盖数千km的距离范围。信号频带包括传统电、磁法不曾包含的,对地震电磁异常现象敏感的极低频及其附近频率的电磁场信号。利用台网进行观测,既可监测空间电磁场的分布及其变化,又可监测台站地下电阻率结构及其变化,利于实现对地震电磁异常的4维监测。在过去10多年的研究和试验中,2次观测到地震前的电磁异常。利用CSELF台网式的观测表明,人工源信号的数据具有稳定的、高信噪比的优势。现在中国具有一定规模的第一个CSELF观测台网正在建设中。
Control Source Extremely Low Frequency(CSELF) electromagnetic technique is a new technique used in the earthquake monitoring. The signals transmitted by powerful generator propagate in "conductance" and cover the regions distant to thousands of kilometers. The signal frequency band contains the ELF and adjacent frequencies which were not used in earthquake monitoring by previous electric and magnetic observations and were understood for their sensitivity to the electromagnetic anomaly relative to events. The CSELF can monitor both the space electromagnetic fields and the sub- surface resistivity structures with their variations, which is favorable for four-dimensional monitoring. In the past experiments, the electromagnetic anomalies before shocks were measured twice. The experimental observation using observatory network-like stations shown that the data of artificial signals are quite stable and have high S/N ratio. A new observatory network with a certain scale is building for earthquake monitoring.