JpGU-AGU Joint Meeting 2017

講演情報

[JJ] ポスター発表

セッション記号 S (固体地球科学) » S-VC 火山学

[S-VC47] [JJ] 活動的火山

2017年5月22日(月) 15:30 〜 17:00 ポスター会場 (国際展示場 7ホール)

コンビーナ:前田 裕太(名古屋大学)、青木 陽介(東京大学地震研究所)

[SVC47-P27] 可視映像解析による桜島昭和火口におけるブルカノ式噴火の衝撃波及び噴煙の時間関係

*村松 弾1相澤 広記1横尾 亮彦2 (1.九州大学、2.京都大学)

To investigate mechanism of Vulcanian eruption, we analyzed eruption movies (30 frame/s) of Showa crater, Sakurajima volcano, Japan. 88 eruptions during December 2011 to May 2015, which accompanied variable infrasound wave, were selected for an analysis. First, we investigated the relationship between an intensity of infrasound and a speed of volcanic plume at the crater. Maximum amplitude of infrasound data observed at Seto and Arimura stations (JMA) shows positive correlations with the ejection speeds of volcanic plume. This result thought to be consistent with preceding vulcanian eruption models (Turcotte et al., 1990; Woods, 1995; Alatorre-Ibargüengoitia et al., 2010) which shows ejection speeds increase if overpressure in the conduit increase. Second, we investigated the time lag between an onset of visible shock wave and a subsequent formation of bright (white) cloud close to the crater. The obtained time lag varies from 0.2 to 1.1 s with maximum frequency 0.6s, and may be related with the variation of size and/or the location of "gas pocket" (e.g., Ishihara, 1985; Iguchi et al., 2008) formed under the crater just before the explosion at Sakurajima.