Spectral Study of Volcanic Micro-Tremors (1) : Propagation of the Micro-tremors of the 1st Kind Observed at Volcano Aso

Abstract

Sassa classified the volcanic micro-tremors of the Volcano Aso into four kinds. The tremor of the 1st kind is expected to be originated near or at the 1st crater, but its properties of propagation are not completely determined. By analyzing the records obtained through tripartite system into Fourier components and taking the correlation between every pair of them, the properties of propagation are examined. It is resulted that the volcanic micro-tremors of the 1st kind originate near the boundary between the 1st and 2nd crater and travels with the phase velocity of about 1,200m/sec at 1-2cps.