Kondo Gen, Aoyama Hiroshi, Nishimura Takeshi, Ripepe Maurizio, Lacanna Giorgio, Genco Riccardo, Kawaguchi Ryohei, Yamada Taishi, Miwa Takahiro, Fujita Eisuke
Graduate School of Science, Hokkaido University, Sapporo, 060-0810, Japan.
Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan.
Sci Rep. 2019 Apr 5;9(1):5678. doi: 10.1038/s41598-019-42033-z.
On August 7, 2014, a new effusive vent opened on the northern flank of Stromboli. A characteristic pattern was observed in both seismic and infrasonic signal amplitudes prior to this effusive eruption. The pattern consisted of the repeating cycle: (1) quiet phase, (2) puffing phase, and (3) explosion phase. Correlation between seismic and infrasound signal suggests that pulses in the puffing phase were caused by repetitive bursts of small gas pockets at the central crater, while the explosion phase coincided with an explosion at the central crater. We show that degassing of the magma column occurred in cycles of increasing gas flux, which controlled the transition from a bubbly flow (puffing phase), to a slug flow (explosion phase) gas regime. The quiet phase was characterized by a constant time length of 150 s, indicating that the gas rose in the magma column as well-organized waves of gas layers. These cycles represent cyclic changes of the gas flux regime in the shallow magma column, associated with increases in the magma-gas supply input rate before the effusive eruption.
2014年8月7日，斯特龙博利火山北侧出现了一个新的溢流喷口。在这次溢流喷发之前，地震和次声信号振幅中都观察到了一种特征模式。该模式由重复循环组成：(1)平静期、(2)喷气期和(3)爆发期。地震信号和次声信号之间的相关性表明，喷气期的脉冲是由中央火山口处小气泡的重复破裂引起的，而爆发期与中央火山口的一次爆炸同时发生。我们表明，岩浆柱的脱气以气体通量增加的周期发生，这控制了从泡状流（喷气期）到段塞流（爆发期）气体状态的转变。平静期的特征是持续时间恒定为150秒，这表明气体以组织良好的气体层波的形式在岩浆柱中上升。这些循环代表了浅部岩浆柱中气体通量状态的周期性变化，与溢流喷发前岩浆-气体供应输入速率的增加有关。
