Magma fragmentation by rapid decompression
Magma fragmentation by rapid decompression
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DOI：
10.1038/380146a0
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发表时间：
1996-03-14
期刊：
影响因子：
64.8
通讯作者：
Dingwell, DB
中科院分区：
文献类型：
--
作者：
Alidibirov, M;Dingwell, DB
在火山爆发过程中，导致岩浆破碎和火山碎屑产生的过程在火山学中具有根本的重要性。对爆炸性喷发的观察（1-3）以及对潜在过程的理论分析提出了这样一个问题，即熔岩穹丘或火山建筑物坍塌所导致的高粘性泡状岩浆的快速减压本身是否会产生爆炸性岩浆破碎和火山碎屑的形成。在这里，我们报告的结果，一个实验室调查的火山碎屑形成后迅速减压。1980年圣海伦火山喷发的岩浆样品，当从最初的12兆帕压力（温度在750-825摄氏度之间）迅速减压时，碎裂形成火山碎屑产物，在许多方面与真实的喷发中形成的产物相似。此外，我们观察到爆炸性碎裂的温度远低于那些通常与岩浆过程，这表明，即使是相对较冷的岩浆体可能是非常危险的，当受到快速卸载事件。
The processes leading to magma fragmentation and the generation of pyroclastic debris during explosive volcanic eruptions are of fundamental importance in volcanology. Observations of explosive eruptions(1-3), as well as theoretical analyses of the underlying processes: have raised the question of whether the rapid decompression of highly viscous, vesicular magma that results from the collapse of a lava dome or volcanic edifice can, in itself, produce explosive magma fragmentation and pyroclast formation. Here we report the results of a laboratory investigation of pyroclast formation following rapid decompression. Samples of magma from the 1980 eruption of Mount St Helens, when rapidly depressurized from initial pressures of up to 12 MPa (and at temperatures in the range 750-825 degrees C), fragmented to form pyroclastic products that are in many respects similar to those formed in real eruptions. Moreover, we observe explosive fragmentation at temperatures well below those normally associated with magmatic processes, suggesting that even relatively cool magma bodies can be very hazardous when subjected to rapid unloading events.