Monitoring of the Time Change in Transfer Functions in the Central Japan Conductivity Anomaly

Abstract

Time change in transfer functions for conductivity anomaly in central Japan is being monitored to detect possible electrical conductivity changes preceding earthquakes. Using geomagnetic data with a sampling interval of one minute, the transfer functions at the Kakioka Magnetic Observatory are calculated day by day. The method of analysis is based on the power spectrum analysis as developed by Everett and Hyndman. Monthly means are statistically obtained from these daily values of transfer functions. Monthly transfer functions during 40 months from January 1976 to April 1979 showed no significant changes. Small fluctuations are likely to be accounted for by seasonal changes probably originating in the external magnetic disturbance. No major earthquake activity has been reported in the vicinity of this site during this period.