新岛台地电场的潮汐响应与地震

本文通过采用频谱分析和BAYTAP-G方法对位于日本伊豆群岛的新岛台跨度达三年（1998～2000年）的地电场的观测资料进行了分析研究，对该台地电场的潮汐响应进行了定量提取与分析，得到了地电场潮汐响应的一些主要特征，例如除了存在全日分潮、半日分潮等不同周期的潮汐成分外，还呈现出明显的半月、半年等不同周期的活动规律.进一步的定量分析显示与新岛台若乡（Wakago）关联的测线的潮汐响应在2000年夏季的群发地震前呈现出不同程度的异常变化，而在所分析的另一条测线中并未检测到类似的异常，这也许可以成为地震电磁信号的“选择性”现象的一种新的证据.

Earthquakes and tide response of geoelectric potential field at the Niijima station

We adopted the spectrum analysis method and the BAYTAP_G method to analyze the geoelectric potential data at the Niijima station during 1998～2000 After the quantitative analysis of the tide response of geoelectric potential changes at the above station, we obtained some main characteristics of the tide response. Besides the tidal components with various periods such as diurnal tide, semi diurnal tide, and so on, semi monthly and semi yearly variations of tide response were also detected from the geoelectric potential data at the Niijima station. Further quantitative analysis showed that some anomalous tide response for the surveying dipoles associated with the Wakago site occurred prior to the earthquake swarm in the summer of 2000, while no clear anomalous tide response for another surveying dipole at the same station. The above result may become a kind of new evidence of the so-called “selectivity" phenomena of seismic electromagnetic signals.