Results 161 to 170 of about 1,522 (205)
International audienceWe address, through quantitative analysis of results from independent studies, the control of the discharge rate of explosive volcanic eruptions on the runout distance of highly hazardous pyroclastic density currents.
O Roche, Nourddine Azzaoui
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Multiphase flow dynamics of stratified pyroclastic density currents
We have simulated the dynamics of pyroclastic density currents to quantify the influence of the vertical stratification of particle concentration on their propagation and runout. The polydisperse pyroclastic mixture is described by discretizing the grain-size distribution into N particle classes and by adopting a non-equilibrium Eulerian transport ...
Orsucci, S. +3 more
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Generation of Overspill Pyroclastic Density Currents in Sinuous Channels
Journal of Geophysical Research: Solid Earth, 2021AbstractDue to their mobility, high velocities, and common occurrence, small‐volume pyroclastic density currents (PDCs) represent a major hazard around volcanoes. Small‐volume events are particularly sensitive to topography and channelization into drainage basins. Understanding the flow transition initiated by avulsion or overspill from valley confined
A. Kubo Hutchison, J. Dufek
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Geological Society, London, Special Publications, 1998
Abstract High-speed, gravity-driven flows of hot particles and gas are a common and highly destructive product of explosive volcanism. They range widely in nature from expanded, turbulent suspension currents formed by lateral blasts or by the fountaining of vertical eruption columns, to highly concentrated granular avalanches ...
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Abstract High-speed, gravity-driven flows of hot particles and gas are a common and highly destructive product of explosive volcanism. They range widely in nature from expanded, turbulent suspension currents formed by lateral blasts or by the fountaining of vertical eruption columns, to highly concentrated granular avalanches ...
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The Fluid Mechanics of Pyroclastic Density Currents
Annual Review of Fluid Mechanics, 2016Pyroclastic density currents are generated in explosive volcanic eruptions when gas and particle mixtures remain denser than the surrounding atmosphere. These mobile currents have a diversity of flow regimes, from energetic granular flows to turbulent suspensions. Given their hazardous nature, much of our understanding of the internal dynamics of these
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Revaluating the Vertical Velocity and Density Structure of Dilute Pyroclastic Density Currents
2023Dilute pyroclastic density currents (dilute PDCs) are frequent and hazardous volcanic phenomena. Better mitigating against PDC hazards requires understanding of the vertical velocity and density structures inside flows and how these are modified during flow runout, particle sedimentation, air entrainment and buoyancy reversal.
Uhle, D., Ardo, J., Lube, G., Jones, J.
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Effects of flow density on the dynamics of dilute pyroclastic density currents
Journal of Volcanology and Geothermal Research, 2004Abstract Dilute turbulent pyroclastic density currents may have densities as large as 10–100 kg m −3 . Laboratory experiments using dense gases show that for such currents, the speed of the head of the current depends on the density difference between the current and the surrounding air in a complex way.
Sarah E. Nield, Andrew W. Woods
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Density Stratification and Buoyancy Evolution in Pyroclastic Density Currents
Journal of Geophysical Research: Solid EarthAbstractPyroclastic density currents (PDCs) are density‐stratified along their vertical axis, with the near‐bed portion being denser than the upper portion, resulting from particle settling and ambient air entrainment at current margins. Whereas vertical density stratification likely influences mixing, sedimentation, and buoyancy of PDCs, many depth ...
Sean B. O’Donnell +6 more
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Generation of air lubrication within pyroclastic density currents
Nature Geoscience, 2019Pyroclastic 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 ...
Gert Lube +6 more
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Pyroclastic Density Currents at Volcán de Colima
2019In the last ~500 years, Volcan de Colima has generated numerous small-volume pyroclastic density currents (PDCs) that have been associated with dome emplacement, either by a partial collapse or by their explosive destruction. Large PDCs were generated by eruption column collapse in 1690, 1818, and 1913.
R. Saucedo +4 more
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