SPECTRAL CHARACTERISTICS OF FORESHOCKS PRECEDING MAJOR EARTHQUAKES OF THE KURILE-KAMCHATKA ARC AND THEIR APPLICATION TO THE PREDICTION OF THE MAIN SHOCK TIME

Abstract

The spectral analysis of waveforms from moderate and weak earthquakes in the Kurile-Kamchatka region allows one to rather reliably discriminate between foreshocks of forthcoming strong events and independent swarms of seismic shocks. Anomalously high frequencies of seismic radiation from foreshock sources are due to an anomalous rigidity of the seismogenic medium. Based on significant frequency anomalies determined from seismic records of foreshock sequences, the methods developed by the authors can be applied to recognize medium- and short-term seismological precursory effects.