Volcanic Micro-Earthquakes at Mt. Aso （Ⅰ）

Abstract

Being disturbed by volcanic micro-tremors, it is difficult to find the initial P waves of micro-earthquakes observed near the crater. Tomoda’s method was applied to obtain the crosscorrelation function between P wave portions of micro-earthquakes recorded at two adjoining stations and hypocentres were determined. The energy spectra of P wave portions of micro-earthquakes were calculated making use of the same method. The frequency at which the maximum value of the spectrum is found varies regularly around the epicentre.