阿蘇火山の短周期火山微動について

概要

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Short period micro-tremors were observed at the volcano Aso for a month from the beginning of July, after the eruption on 24th June 1958. The observations were made with the moving coil type seismometric pick-ups which are connected directly to galvanometers, the free oscillation frequencies being 2 and 30 cycles respectively. The observing points were distributed in the area within 1km from the active crater. The velocities as well as directions of propagation of the volcanic micro-tremors were obtained by tripartite observations. The frequency-distribution of periods was deduced from the analysis of the results of the same tripartite observations. The results obtained are; 1. The predominant periods of the volcanic micro-tremors are 0.25sec. at Hondo and the Volcano Museum and 0.2sec. at Sunasenri. 2. The propagating velocities of the volcanic micro-tremors at Hondo and the Volcano Museum are 1.5-4.0km/sec., while 0.5-3.0km/sec. at Sunasenri. 3. The origin of micro-tremors deduced from the rate of variations in propagating velocities near crater must be as deep as 700-900m. from the surface. 4. The predominant direction of oscillation of the volcanic micro-tremors is perpendicular to that of the propagation.
特定非営利活動法人日本火山学会の論文
1959-02-20