用分析和数值模型探讨冰川火山空洞的形成和持续性

IF 2.8 3区 地球科学 Q2 GEOGRAPHY, PHYSICAL
Tryggvi Unnsteinsson, Gwenn E. Flowers, Glyn Williams-Jones
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引用次数: 0

摘要

地球上五分之一的火山都被冰雪覆盖,许多火山都有活跃的地热系统,与上覆的冰相互作用。这些冰川与火山的相互作用会将空隙融化成冰川,并受到冰动力学和地热输出的控制。据观察,冰川火山空洞会在火山喷发前形成,当在加拿大不列颠哥伦比亚省 Qw̓elqw̓elústen(米格火山群)的乔布冰川内发现此类特征时,引起了人们的关注。在这项研究中,我们使用分析和数值模型来模拟冰川火山空洞的形成、演变和稳态形态。分析稳态空洞几何形状显示空洞高度仅限于冰厚度的四分之一,而数值模型结果表明空洞高度h与冰厚度H和地热通量$\dot {Q}$成比例关系,即$h/H = a H^b \dot {Q}^c$,指数b = -n/2,c = 1/2,其中n为蠕变指数。将这一比例应用于乔布冰川内的冰川火山空隙表明,总地热通量有可能超过 10 兆瓦。我们的研究结果表明,冰层厚度的相对变化比地热通量的相对变化更能影响冰川火山空隙的形成和演化。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Formation and persistence of glaciovolcanic voids explored with analytical and numerical models

One fifth of Earth's volcanoes are covered by snow or ice and many have active geothermal systems that interact with the overlying ice. These glaciovolcanic interactions can melt voids into glaciers, and are subject to controls exerted by ice dynamics and geothermal heat output. Glaciovolcanic voids have been observed to form prior to volcanic eruptions, which raised concerns when such features were discovered within Job Glacier on Qw̓elqw̓elústen (Mount Meager Volcanic Complex), British Columbia, Canada. In this study we model the formation, evolution, and steady-state morphology of glaciovolcanic voids using analytical and numerical models. Analytical steady-state void geometries show cave height limited to one quarter of the ice thickness, while numerical model results suggest the void height h scales with ice thickness H and geothermal heat flux $\dot {Q}$ as $h/H = a H^b \dot {Q}^c$, with exponents b = −n/2 and c = 1/2 where n is the creep exponent. Applying this scaling to the glaciovolcanic voids within Job Glacier suggests the potential for total geothermal heat flux in excess of 10 MW. Our results show that relative changes in ice thickness are more influential in glaciovolcanic void formation and evolution than relative changes in geothermal heat flux.

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来源期刊
Journal of Glaciology
Journal of Glaciology 地学-地球科学综合
CiteScore
5.80
自引率
14.70%
发文量
101
审稿时长
6 months
期刊介绍: Journal of Glaciology publishes original scientific articles and letters in any aspect of glaciology- the study of ice. Studies of natural, artificial, and extraterrestrial ice and snow, as well as interactions between ice, snow and the atmospheric, oceanic and subglacial environment are all eligible. They may be based on field work, remote sensing, laboratory investigations, theoretical analysis or numerical modelling, or may report on newly developed glaciological instruments. Subjects covered recently in the Journal have included palaeoclimatology and the chemistry of the atmosphere as revealed in ice cores; theoretical and applied physics and chemistry of ice; the dynamics of glaciers and ice sheets, and changes in their extent and mass under climatic forcing; glacier energy balances at all scales; glacial landforms, and glaciers as geomorphic agents; snow science in all its aspects; ice as a host for surface and subglacial ecosystems; sea ice, icebergs and lake ice; and avalanche dynamics and other glacial hazards to human activity. Studies of permafrost and of ice in the Earth’s atmosphere are also within the domain of the Journal, as are interdisciplinary applications to engineering, biological, and social sciences, and studies in the history of glaciology.
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