气候变化领域集成服务门户(CCPortal): Comparison of Bubble Shape Model Results With Textural Analysis: Implications for the Velocity Profile Across a Volcanic Conduit

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DOI	10.1029/2021JB021841
	Comparison of Bubble Shape Model Results With Textural Analysis: Implications for the Velocity Profile Across a Volcanic Conduit
	Ohashi M.; Ichihara M.; Kennedy B.; Gravley D.
发表日期	2021
ISSN	21699313
卷号	126 期号:6
英文摘要	Tube pumice, which is characterized by aligned elongated bubbles, is valuable for our understanding of the shear field in a volcanic conduit. Most previous studies interpreted that tube pumice forms through simple shear, assuming a parabolic velocity profile across a volcanic conduit. However, simple shear cannot account for the observation that tube pumice is rare in plinian fall deposits but frequent in ignimbrites at the Taupō volcano, if the pyroclastic flows that formed them erupted through a wider vent and had a lower average shear rate. Here, we analyze the dynamics of bubble deformation that occurred during the 232 CE Taupō eruption by combining a bubble deformation model with a conduit flow model. The results indicate that bubble deformation is largely controlled by the velocity profile across a conduit. If the conduit flow has a parabolic velocity profile, the amount of bubble elongation is unrealistic compared to the Taupō fall deposits. It is more likely that the conduit flow has a plug-like velocity profile due to viscous heating. We numerically confirmed that bubbles in the plug-like flow are subject mainly to pure shear and accumulate less strain for elongation. We also calculated a viscous heating flow of the ignimbrite phase. We modeled a wider conduit, which suppresses viscous heating around the conduit walls and causes a higher proportion of the conduit to experience parabolic flow, compared to the plinian phase. The increased proportion of a parabolic profile may explain the high frequency of elongated bubbles in the ignimbrite phase pumice. © 2021. American Geophysical Union. All Rights Reserved.
英文关键词	bubble deformation; bubble texture; conduit flow; tube pumice
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187053
作者单位	Earthquake Research Institute, University of Tokyo, Tokyo, Japan; Department of Earth and Planetary Sciences, Kyushu University, Fukuoka, Japan; Department of Geological Sciences, University of Canterbury, Christchurch, New Zealand
推荐引用方式 GB/T 7714	Ohashi M.,Ichihara M.,Kennedy B.,et al. Comparison of Bubble Shape Model Results With Textural Analysis: Implications for the Velocity Profile Across a Volcanic Conduit[J],2021,126(6).
APA	Ohashi M.,Ichihara M.,Kennedy B.,&Gravley D..(2021).Comparison of Bubble Shape Model Results With Textural Analysis: Implications for the Velocity Profile Across a Volcanic Conduit.Journal of Geophysical Research: Solid Earth,126(6).
MLA	Ohashi M.,et al."Comparison of Bubble Shape Model Results With Textural Analysis: Implications for the Velocity Profile Across a Volcanic Conduit".Journal of Geophysical Research: Solid Earth 126.6(2021).