Years to weeks of seismic unrest and magmatic intrusions precede monogenetic eruptions
Years to weeks of seismic unrest and magmatic intrusions precede monogenetic eruptions
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DOI：
10.1130/g37239.1
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发表时间：
2016-03-01
期刊：
影响因子：
5.8
通讯作者：
Marti, Joan
中科院分区：
文献类型：
--
作者：
Albert, Helena;Costa, Fidel;Marti, Joan
地震、变形和气体活动（不稳定）通常发生在火山爆发之前。利用监测数据跟踪这种活动的变化，使人们越来越有可能成功地预测平流层火山的喷发。然而，单基因火山并非如此。这些火山的喷发往往很小，但特别难以预测，因为它们发生在意想不到的地点，而且仪器监测数据非常有限。许多单基因火山场发生在高密度、人口稠密的地区和/或旅游目的地，因此即使是一次小的喷发也会产生重大的经济和社会影响。我们收集了有关动荡的可用仪器数据，并将其与新的地震活动历史记录结合起来。我们的发生地主要来自高岩浆通量的海洋岛屿（加那利群岛、冰岛、巴布亚新几内亚、墨西哥和日本）。我们发现地震活动可能在喷发前一到两年开始，但在大约两到三个月和一到两周时加剧。矿床的岩石学和地球化学特征表明，该次火山岩储层中存在多批岩浆相互作用，多次侵入与地震活动时间尺度相似。我们提出了这些喷发的一般模型，其中地壳中的早期岩脉侵入不喷发（例如，停滞的侵入）并形成小型管道系统，但它们可能是为后来的岩脉能够到达地表创造热流变途径的关键。这些观测结果为更好地预测类似环境下的单成因喷发和岩浆通量提供了一个概念性框架，并应有助于改进减轻其相关危害和风险的战略。
Seismic, deformation, and gas activity (unrest) typically precedes volcanic eruptions. Tracking the changes of this activity with monitoring data makes it increasingly possible to successfully forecast eruptions from stratovolcanoes. However, this is not the case for monogenetic volcanoes. Eruptions from these volcanoes tend to be small but are particularly difficult to anticipate since they occur at unexpected locations and there is very limited instrumental monitoring data. Many monogenetic volcanic fields occur in high-density, populated areas and/or tourist destinations, and thus even a small eruption can have a major economic and societal impact. We have gathered the available instrumental data for unrest and combined it with new historical accounts of seismicity. Our occurrences are mainly from high magmatic flux oceanic islands (Canary Islands, Iceland, Papua New Guinea, Mexico, and Japan). We find that seismic activity may start one or two years before eruption, but it intensifies at approximately two or three months, and one or two weeks. The petrological and geochemical characteristics of the deposits show that multiple magma batches interacted in a subvolcanic reservoir, and multiple intrusions occurred on a similar time scales to the seismicity. We propose a general model for these eruptions where early dike intrusions in the crust do not erupt (e.g., stalled intrusions) and make small plumbing systems, but they probably are key in creating a thermal and rheological pathway for later dikes to be able to reach the surface. These observations provide a conceptual framework for better anticipating monogenetic eruptions in similar settings and magmatic fluxes and should lead to improved strategies for mitigation of their associated hazards and risks.