气候变化领域集成服务门户(CCPortal): Generation of air lubrication within pyroclastic density currents

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DOI	10.1038/s41561-019-0338-2
	Generation of air lubrication within pyroclastic density currents
	Lube G.; Breard E.C.P.; Jones J.; Fullard L.; Dufek J.; Cronin S.J.; Wang T.
发表日期	2019
ISSN	17520894
卷号	12 期号:5
英文摘要	Pyroclastic density currents are highly dangerous ground-hugging currents from volcanoes that cause >50% of volcanic fatalities globally. These hot mixtures of volcanic particles and gas exhibit remarkable fluidity, which allows them to transport thousands to millions of tonnes of volcanic material across the Earth’s surface over tens to hundreds of kilometres, bypassing tortuous flow paths and ignoring rough substrates and flat and upsloping terrain. Their fluidity is attributed to an internal process that counters granular friction. However, it is difficult to measure inside pyroclastic density currents to quantify such a friction-defying mechanism. Here we show, through large-scale experiments and numerical multiphase modelling, that pyroclastic density currents generate their own air lubrication. This forms a near-frictionless basal region. Air lubrication develops under high basal shear when air is locally forced downwards by reversed pressure gradients and displaces particles upward. We show that air lubrication is enhanced through a positive feedback mechanism, explaining how pyroclastic density currents are able to propagate over slopes much shallower than the angle of repose of any natural granular material. This discovery necessitates a re-evaluation of hazard models that aim to predict the velocity, runout and spreading of pyroclastic density currents. © 2019, The Author(s), under exclusive licence to Springer Nature Limited.
语种	英语
scopus关键词	lubricant; modeling; pressure gradient; slope; velocity profile; volcano
来源期刊	Nature Geoscience
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/124676
作者单位	Institute of Geoscience, College of Sciences, Massey University, Palmerston North, New Zealand; Department of Earth Sciences, University of Oregon, Eugene, OR, United States; School of Engineering and Advanced Technology, College of Sciences, Massey University, Palmerston North, New Zealand; Institute of Fundamental Sciences, College of Sciences, Massey University, Palmerston North, New Zealand; School of Environment, University of Auckland, Auckland, New Zealand; Department of Mathematics and Statistics, University of Otago, Dunedin, New Zealand
推荐引用方式 GB/T 7714	Lube G.,Breard E.C.P.,Jones J.,et al. Generation of air lubrication within pyroclastic density currents[J],2019,12(5).
APA	Lube G..,Breard E.C.P..,Jones J..,Fullard L..,Dufek J..,...&Wang T..(2019).Generation of air lubrication within pyroclastic density currents.Nature Geoscience,12(5).
MLA	Lube G.,et al."Generation of air lubrication within pyroclastic density currents".Nature Geoscience 12.5(2019).