Observation of earth-potential using telegraphic facilities and analysis with BAYTAP-G

Abstract

Since 1985, highly stable digital measurements of the earth-potential have been obtained using the telegraphic facilities of NTT at Mito and Numazu, Japan. At Mito, the observed data are fairly noiseless, while at Numazu, they contain large amplitude noise. The data at Mito were analyzed using a program, BAYTAP-G , aimed at improving the detectability of the anomalous phenomena associated with tectonic activities. The observed earth-potential data were separated into four components: 1) tidal, 2) electromagnetically induced, 3) trend and 4) irregular component. Because the trend and irregular components indicate the variation of the self-potential of the crust and/or noise, signals due to volcanic and/or seismic activity can in principle be detected, provided that their amplitudes exceed that of the usual variation. Though we have not yet observed any correlation between earth-potential variations and seismicity at Mito, we have established a practical method for reduction (or separation) of the induced and tidal components.

Modeling of seismo-electromagnetic phenomena

“…This search has been conducted in many areas of high seismic activity worldwide (Japan [Fukutomi, 1934;Miyakoshi, 1986;Noto, 1933;Ozima et al, 1989;Shiratori, 1925;Uyeda, et al, 2000], the former Soviet Union [Sobolev et al, 1981], Greece [Lighthill, 1996;Varotsos and Alexopoulos, 1984a, 1984bVarotsos et al, 1993], China [Qian et al, 1990;Raleigh et al, 1977], Bulgaria [Ralchovsky and Komarov, 1987], USA [Sornette and Sornette, 1990]). Several hundred cases have been reported which relate such anomalies to strong nearby quakes.…”

Earthquakes and Tide Response of Geoelectric Potential Field at the Niijima Station

“…The BAYTAP-G method is a general analysis program for earth tides and crustal movements, which was developed jointly by the Institute of Statistical Mathematics and the National Astronomical Observatory, Japan. It has been applied to various research fields, e.g., Ozima et al [33] first applied it to the analysis of the geoelectric data.…”