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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >The generation of gas overpressure in volcanic eruptions
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The generation of gas overpressure in volcanic eruptions

机译：火山喷发中气体超压的产生

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Observations of natural eruption products show that different parts of a single magma batch may experience different degassing histories during ascent in a volcanic conduit. In non-explosive eruptions, lava issuing from a volcanic vent may contain overpressured gas bubbles. These important features of volcanic eruptions cannot be accounted for by existing flow models, which rely on simplifying hypotheses for the relationship between pressures in the gas phase and in the bulk flow. Volcanic flows involve highly compressible material which undergoes large viscosity variations as degassing proceeds. We show that these properties may lead to large gas overpressures in erupting lava. The magnitude of this overpressure depends on the initial volatile content of magma and is largest for relatively volatile-poor magmas, due to the extreme viscosity variations at water contents less than 1 wt%. We develop a simple analytical model to illustrate the main features of compressible viscous flows: (1) at any level, gas pressure is larger near the conduit axis than at the walls, (2) gas overpressure is an increasing function of mass discharge rate.
机译：对自然喷发产物的观察表明，单个岩浆批次的不同部分在火山管道中上升过程中可能经历不同的除气历史。在非爆炸性喷发中，从火山喷口喷出的熔岩可能包含超压气泡。现有的流动模型无法解释火山喷发的这些重要特征，现有的流动模型依赖于简化气相和整体流动压力之间关系的假设。火山流涉及高度可压缩的材料，随着脱气的进行，粘度会发生较大的变化。我们表明，这些性质可能导致熔岩喷发中的巨大气体超压。该超压的大小取决于岩浆的初始挥发性含量，并且由于水含量小于1 wt％时的极端粘度变化，对于相对挥发性较差的岩浆来说，最大压力是最大的。我们开发了一个简单的分析模型来说明可压缩粘性流的主要特征：（1）在任何水平下，导管轴线附近的气压都大于壁上的气压;（2）气体超压是质量排放速率的增加函数。

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