First detection of precursory ground inflation of a small phreatic eruption by InSAR
First detection of precursory ground inflation of a small phreatic eruption by InSAR
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DOI：
10.1016/j.epsl.2018.03.041
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发表时间：
2018-06
影响因子：
5.3
通讯作者：
Tomokazu Kobayashi;Y. Morishita;H. Munekane
中科院分区：
文献类型：
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作者：
Tomokazu Kobayashi;Y. Morishita;H. Munekane
潜水喷发是由浅层地热流体源加压引起的。与典型的岩浆喷发相比，它们相对较小，但可能非常危险。然而，由于其规模小，其发生难以预测。在这里，我们显示了检测本地分布的地面膨胀之前，在箱根火山，日本，小潜水喷发，通过应用干涉合成孔径雷达分析。火山喷发初期，地面膨胀以每月1.5mm的速度缓慢进行，空间尺度约为1.200m，在800-900年来首次喷发前2个月，地面膨胀加速，地面抬升达1.30cm，喷发发生在变形最大的部位附近。变形速度与位于海平面以下4.8km的球形源的膨胀有很好的相关性，因此，来自球形源（可能是岩浆库）的热量和/或火山流体供应直接驱动了地下热液活动。我们的研究结果表明，高空间分辨率的变形数据可以是一个很好的指示地下压力条件与精确的空间精度在潜水喷发的准备过程中。
Phreatic eruptions are caused by pressurization of geothermal fluid sources at shallow levels. They are relatively small compared to typical magmatic eruptions, but can be very hazardous. However, owing to their small magnitudes, their occurrences are difficult to predict. Here we show the detection of locally distributed ground inflation preceding a small phreatic eruption at the Hakone volcano, Japan, through the application of interferometric synthetic aperture radar analysis. The ground inflation proceeded the eruption at slow speed of ∼5 mm/month with a spatial size of ∼200 m in the early stage, and then it accelerated 2 months before the eruption that occurred for the first time in 800–900 yrs. The ground uplift reached ∼30 cm, and the eruption occurred nearby the most deformed part. The deformation speed correlated well with inflation of spherical source located at 4.8 km below sea level, thus suggesting that heat and/or volcanic fluid supply from the spherical source, maybe magma reservoir, directly drove the subsurface hydrothermal activity. Our results demonstrate that high-spatial-resolution deformation data can be a good indicator of subsurface pressure conditions with pinpoint spatial accuracy during the preparatory process of phreatic eruptions.