Magma Ascent and the Style of Volcanic Eruptions
Magma Ascent and the Style of Volcanic Eruptions
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DOI：
10.1016/j.epsl.2006.11.016
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发表时间：
2006-12
期刊：
影响因子：
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通讯作者：
R. Scandone;K. Cashman;S. Malone
中科院分区：
文献类型：
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作者：
R. Scandone;K. Cashman;S. Malone
我们提出了一种新的方法来观察导致不同风格的硅火山喷发的事件序列。中小规模的喷发，无论是爆发性的还是喷涌性的，都可以用中地壳岩浆房中孤立岩浆的上升来解释。我们将岩浆上升分为四个不同的区域：供给系统、中间储存系统、输送系统和喷发系统。最重要的是，从中间储集系统通过输送系统上升到喷发系统首先需要一个裂缝网络的发展。最初，这个断裂网络允许单个岩浆批次的上升，在它们通过后打开，然后关闭。随着时间的推移，裂缝网络复杂性的增加增加了裂缝的连通性，从而增加了岩浆向上运动的便利性。在这个模型中，随后爆发的动力学完全由在运输系统中花费的时间控制。大型爆发需要从中间储存系统到爆发系统的运输系统的完全互连。此外，我们认为完全连接的管道是罕见的，只在特定条件下发展，并且通常在形成过程中产生灾难性的喷发。在这里，我们研究了说明这些过程相互作用的两个历史案例：1980年至2004年美国的圣海伦斯山和1991年菲律宾的皮纳图博山。
We propose a new way of looking at the sequence of events leading to different styles of silicic, volcanic eruptions. Small-to-medium sized eruptions, either explosive or effusive, are explained by the ascent of isolated magma batches from mid-crustal magma chambers. We separate magma ascent into four different zones: the Supply System, the Intermediate Storage System, the Transport System and the Eruptive System. Of primary importance is the concept that ascent from the Intermediate Storage System through the Transport System to the Eruptive System first requires the development of a fracture network. Initially, this fracture network allows the ascent of individual magma batches by opening and then closing after their passage. An increase in the complexity of the fracture network with time increases the connectivity of the fractures and hence the ease of upward magma movement. In this model, the dynamics of the ensuing eruptions are controlled entirely by the time spent in the Transport System. Large explosive eruptions require a full interconnectivity of the Transport System from the Intermediate Storage System to the Eruptive System. Moreover, we suggest that a fully connected conduit is rare, develops only under particular conditions, and typically generates catastrophic eruptions during formation. Here we examine two case histories that illustrate the interplay of these processes: Mt St. Helens, USA, between 1980 and 2004, and Mt. Pinatubo, Philippines, in 1991.