Changes to the volcanic outgassing mechanism and very-long-period seismicity from 2007 to 2011 at Mt. Asama, Japan
Changes to the volcanic outgassing mechanism and very-long-period seismicity from 2007 to 2011 at Mt. Asama, Japan
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DOI：
10.1016/j.epsl.2015.02.034
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发表时间：
2015-05-15
影响因子：
5.3
通讯作者：
Takeo, Minoru
中科院分区：
文献类型：
--
作者：
Kazahaya, Ryunosuke;Maeda, Yuta;Takeo, Minoru
火山气体可以提供有关岩浆状态的重要信息，这对于解释和预测火山活动具有重要意义。我们提出了一个研究的地震和火山气体从山。Asama，日本从2007年到2011年，以阐明火山气体供应机制的变化对超长周期（VLP）地震事件的影响。两种类型的脱气发生在山。浅间：VLP地震事件后的持续脱气和气体爆发（无灰喷发）。我们使用地震矩和二氧化硫（SO2）排放量之间的线性关系，和地震记录来估计的SO2气体的量在无灰喷发，这导致VLP地震事件。利用SO2含量和火山气体成分数据计算了火山气体的含量，包括H2O、CO2和其他物质。我们比较了无灰喷发的火山气体排放率（喷发气体排放率）和包括持续脱气的总火山气体排放率。喷发气体排放速率与总气体排放速率的比值（喷发/总气体比值）随喷发而发生剧烈变化。在2008年火山爆发之前和2009年火山爆发之后，火山活动有所增加。VLP地震事件可能是由气相膨胀和破裂的传播引起的浅部突然放气引起的。我们认为，突然放气的速率控制的气相在管道中的分布。喷发气体排放率的变化表明在管道中的气相分布的变化。(C)2015爱思唯尔B. V.保留所有权利。
Volcanic gases can provide significant information on the state of magma, which is important for interpreting and predicting volcanic activity. We present a study of the seismicity and volcanic gases from Mt. Asama, Japan from 2007 to 2011 to elucidate the change in the mechanism of volcanic gas supply for very-long-period (VLP) seismic events. Two types of degassing occur at Mt. Asama: persistent degassing and a gas burst (ash-free eruption) following a VLP seismic event. We used the linear relationship between the seismic moment and sulfur dioxide (SO2) emissions, and seismic records to estimate the quantity of SO2 gas in the ash-free eruption, which causes the VLP seismic events. The amount of SO2 and volcanic gas composition data were used to calculate the amount of volcanic gases, including H2O, CO2, and other species. We compared the volcanic gas emission rates of ash-free eruptions (eruptive gas emission rates) and total volcanic gas emission rates including the persistent degassing. The ratio of the eruptive gas emission rate to the total gas emission rate (eruptive/total gas ratios) showed a drastic change with eruption. An increase occurred immediately before the 2008 and after the 2009 eruptions. The VLP seismic events are likely caused by sudden outgassing at a shallow depth that is induced by the propagation of the gas phase expansion and rupture. We suggest that the rates of sudden outgassing are controlled by the distribution of gas phases in the conduit. The variability of the eruptive gas emission rates suggests changes in the gas phase distribution in the conduit. (C) 2015 Elsevier B.V. All rights reserved.