A Study on Air Vibration Caused by Volcanic Explosions

YOSHIDOME Michiya, SEINO Masaaki

doi:10.18940/kazanc.13.3_141

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Other Title

火山爆発に伴う空振の一調査
カザンバクハツニトモナウクウシンノイチチョウサ

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Description

The air vibration, caused by the explosion of Volcano Kuchinoerabujima on November 22 in 1966, was recorded with electromagnetic seismograph in Volcano Sakurajima. The figure of the record at Station B in Sakurajima, 134 km in distance from explosion source, was apparently similar to that of seismic wave (Fig. 2). Therefore, it was necessary to investigate this record in detail. The problem of air vibration was generally studied on the path and arrival time of wave propagation in the atmosphere, using ‘ray theory’. In this paper, we studied on the energy of wave as well as path and arrival time in moving air. The results were summarized as follows. 1) The air vibration was dispersed in 4 phases, and arrived at Station B through different paths (Fig. 5). 2) Waves of each phase had different values on energy (E_n) and arrival time (t_n). Theoretical results, E₁ : E₂ : E₃ : E₄=1/2 : 1/0.9 : 1/0.7 : 1/40 and t₁ : t₂ : t₃ : t₄=404 : 414 : 426 : 436 (sec), showed good agreements to observed results of the record of seismograph. 3) Such dispersions of air vibration become more distinct where it is farther from the source.

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