抄録
Five geoelectric potential difference (electric field, here after) monitoring stations have been in operation since September 1997 in an area near Liwa town, southern Sumatra, Indonesia, to examine the relationship between electric field changes and earthquakes. Short-term electric field variations were found to correspond mainly to geomagnetic activity, while long-term variation was mostly gradual shift and was clearly correlated neither precipitation nor ground water level variations. Co-seismic electric field changes ranging between 1 and 8 mV were observed for five mb > 5 earthquakes at multiple stations during September-December 1997. The epicenters of the earthquakes were in the Indian Ocean within about 170 km from the monitoring sites.
