Implications of deflation-inflation event models on Kilauea Volcano, Hawai'i
Implications of deflation-inflation event models on Kilauea Volcano, Hawai'i
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DOI：
10.1016/j.jvolgeores.2020.106832
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发表时间：
2020-05-15
影响因子：
2.9
通讯作者：
Frazer, Neil
中科院分区：
文献类型：
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作者：
Anderson, Alyssa N.;Foster, Ames H.;Frazer, Neil
火山区地表形变可以揭示地下岩浆储集层以及岩浆如何在地下储集层之间输送的信息，是火山减灾监测的重要组成部分。在夏威夷基拉韦厄火山观察到的一个突出的形变类型是断续的通货紧缩-膨胀(DI)事件，它记录在地表形变数据中，其特征是顶峰地区在几个小时到几天的时间内发生通货紧缩，然后迅速再膨胀。DI事件的确切原因尚不清楚，但通常提出的解释是，连接南部火山口岩浆储集层和较浅的Halema‘uma’u储集层的管道发生了暂时堵塞，从而中断了岩浆的流入。这一模型是通过检验假设来检验的，即在DI事件的收缩阶段，阻止到达Halemailma‘u水库的岩浆体积被添加到南破火山口水库。使用质量平衡法和变形模型，预测了储层的预期变形(倾斜)模式，并将其与2010至2012年间16个大型(4亩弧度)DI事件的倾斜观测进行了比较。虽然预测的来自南破火山口水库的膨胀造成的倾斜足够强烈，足以被检测到，但在倾斜观测中看不到这个信号。我们还探讨了堵塞发生在南破火山口水库下方的可能性，以及包括南破火山口水库与喷发点之间直接连接的替代配置。我们测试的简单的双水库模型都不能充分满足观测结果。选定的DI事件表明，倾斜向量在通货紧缩过程中在震级和方位方向上都发生了变化。我们的结论是，在这些DI事件期间，峰顶储存和管道系统的活动部分比两个相连的洞室要复杂得多，这些峰顶储集层更有可能有自己的源水管道，以某种复杂的方式连接到深部岩浆源。(C)2020爱思唯尔B.V.保留所有权利。
Surface deformation of volcanic areas can reveal information about subsurface magma reservoirs and how magma is transported between them, which is an important part of volcano monitoring for hazard mitigation. One prominent style of deformation observed at Kilauea volcano, Hawai'i, is episodic deflation-inflation (DI) events, which are recorded in surface deformation data and characterized by deflation of the summit region over hours to days followed by rapid re-inflation. The exact cause of DI events is unknown, however, a commonly proposed explanation is that a temporary blockage occurs in the conduit connecting the south caldera magma reservoir to the shallower Halema'uma'u reservoir, thus interrupting the influx of magma. This model is investigated by testing the hypothesis that during the deflationary phase of a DI event, the volume of magma blocked from reaching the Halemailma'u reservoir is added to the south caldera reservoir. Using a mass balance approach and deformation modeling, the expected deformation (tilt) pattern was predicted for the reservoirs and compared to tilt observations from 16 large (>4 mu rad magnitude) DI events between 2010 and 2012. While the predicted tilts due to inflation from the south caldera reservoir are strong enough to be detected, this signal is not seen in the tilt observations. We also explore the possibility that the blockage occurs below the south caldera reservoir, as well as alternative configurations that include a direct connection between the south caldera reservoir and the eruption site. None of the simple two-reservoir models we test are able to adequately satisfy the observations. Selected DI events show that tilt vectors change in both magnitude and azimuthal direction over the course of deflation. We conclude that the portion of the summit storage and plumbing system active during these DI events is more complicated than two connected chambers, and that it is more likely that these summit reservoirs have their own source conduits connecting in some complex way to the deep magma source. (C) 2020 Elsevier B.V. All rights reserved.