Degassing activity from Iwodake rhyolitic cone, Satsuma-Iwojima volcano, Japan: Formation of a new degassing vent, 1990-1999
Degassing activity from Iwodake rhyolitic cone, Satsuma-Iwojima volcano, Japan: Formation of a new degassing vent, 1990-1999
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DOI：
10.1186/bf03353017
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发表时间：
2002-01-01
影响因子：
3
通讯作者：
Kawanabe, Y
中科院分区：
文献类型：
--
作者：
Shinohara, H;Kazahaya, K;Kawanabe, Y
从1990年到1999年，在萨摩硫磺岛火山硫磺岳锥顶火山口观察到脱气活动的表面表现发生了巨大变化。在此期间，火山口底部中心形成了一个新的高温喷气孔区域，并成为直径为40 m的排气口。蚀变的火山岩在喷口形成过程中被喷出。尽管在喷射的火山灰中观察到了玻璃碎片，但这些玻璃来自覆盖火山口底部的蚀变硫磺岳流纹岩。在喷口形成之初，火山气体的最高延胡索温度和平衡温度最高约为900℃。 COSPEC 测量的 SO2 通量从 300 吨/天到 700 吨/天不等，与最大喷气孔温度直接相关。在此期间，沿着火山口南缘形成开放裂缝，几乎与喷口形成和喷气孔排放性质的变化同时发生。萨摩琉岛持续而强烈的脱气可能是由深层岩浆房通过对流岩浆柱的挥发性输送引起的。岩浆对流速率的增加可能导致了地表表现的巨大变化，包括 SO2 通量和喷气温度的增加、地面变形和喷口的形成。
Large changes in the surface manifestation of degassing activity were observed from 1990 to 1999 at the summit crater of Iwodake cone of Satsuma-Iwojima volcano. During this period, a new high-temperature fumarolic area formed in the center of the crater floor and became a degassing vent with a diameter of 40 m. Altered volcanic rocks were ejected during the course of vent formation. Although glass fragments were observed in the ejected ash, the glass comes from altered Iwodake rhyolite that covers the crater floor. The highest fumarolic temperature and equilibrium temperatures of volcanic gases had a maximum of about 900degreesC at the, beginning of the vent formation. The flux of SO2, measured by COSPEC, varied from 300 to 700 ton/day and correlated directly with maximum fumarole temperature. During this period, open fractures formed along the southern rim of the crater almost contemporaneously with the vent formation and changes in the nature of fumarolic discharges. The continuous and intense degassing at Satsuma-lwojima is likely caused by volatile transport from a deep magma chamber through a convecting magma column. An increase in the magma convection rate might have caused these large changes in surface manifestations, including increase in the SO2 flux and fumarolic temperatures, ground deformation, and the vent formation.