Hydrothermal system of the active crater of Aso volcano (Japan) inferred from a three-dimensional resistivity structure model
Hydrothermal system of the active crater of Aso volcano (Japan) inferred from a three-dimensional resistivity structure model
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DOI：
10.1186/s40623-019-1017-7
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发表时间：
2019-04-10
影响因子：
3
通讯作者：
Inoue, Hiroyuki
中科院分区：
文献类型：
--
作者：
Kanda, Wataru;Utsugi, Mitsuru;Inoue, Hiroyuki
在过去20年中，对日本阿索火山的研究增进了我们对该火山活火山口下存在的浅层热液系统的了解。详细了解这种火山建筑物的地下结构，对于更好地了解火山流体的行为和火山爆发的触发机制至关重要。在这里，我们报告了一个三维（3-D）电阻率模型的活动火山口的中岳中心锥的阿索火山使用音频大地电磁（AMT）数据在2004-2005年期间获得的。AMT数据是在陨石坑周围的43个网格（网格点之间的距离：300米）上收集的。然而，到目前为止，只有二维截面电阻率模型已产生的这个调查区。利用三维反演，我们得到了一个电阻率模型，表现出类似的特性，那些的二维模型。在活跃的火山口下方观察到一个高度导电的区域，深度约为300米。根据最近的研究结果，浅热液系统的火山，我们解释这个导电带已形成高导电性酸性流体填充断裂区域。这一观点修改了过去对二维模型的解释，并促进了对活动陨石坑下流体行为的理解。
During the past two decades, studies of the Aso volcano in Japan have improved our understanding of the shallow hydrothermal system that exists beneath the active crater of this volcano. Detailed knowledge of the subsurface structure of this volcanic edifice is essential for developing a better understanding of the behavior of the volcanic fluids and of the triggering mechanism of volcanic eruptions. Here, we report a three-dimensional (3-D) electrical resistivity model for the active crater of the Nakadake central cone of Aso volcano using audio-frequency magnetotelluric (AMT) data obtained during 2004-2005. The AMT data were collected at 43 sites on a grid (distance between grid points:300m) around the crater. However, as yet, only two-dimensional sectional resistivity models have been generated for this survey area. Using 3-D inversion, we obtain a resistivity model that shows similar characteristics to those of the 2-D models. A highly conductive zone is observed beneath the active crater down to a depth of approximately 300m. Based on the recent findings regarding the shallow hydrothermal system of the volcano, we interpret this conductive zone to have been formed by highly conductive acidic fluids filling a fractured region. This view modifies the past interpretation made on the 2-D models and promotes understanding of fluid behavior beneath the active crater.