Slow-moving and far-travelled dense pyroclastic flows during the Peach Spring super-eruption

Roche, Olivier; Buesch, David C.; Valentine, Greg A.

doi:10.1038/ncomms10890

Cited by 82 publications

(55 citation statements)

References 31 publications

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“…The meaning of the negative pore pressure in experiments was thought to be related to basal slip boundary condition as shown in Roche et al (), and the maximum value of the negative peak was empirically correlated to the flow front velocity. This empirical law was used to approximate front velocities of natural flows (see Roche et al, ). Here we show that the whole pore pressure signal can be calculated based upon local physical properties of the flow.…”

Section: Resultsmentioning

confidence: 99%

Continuum Modeling of Pressure‐Balanced and Fluidized Granular Flows in 2‐D: Comparison With Glass Bead Experiments and Implications for Concentrated Pyroclastic Density Currents

2019

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Granular flows are found across multiple geophysical environments and include pyroclastic density currents, debris flows, and avalanches, among others. The key to describing transport of these hazardous flows is the rheology of these complex multiphase mixtures. Here we use the multiphase model MFIX in 2‐D for concentrated currents to examine the implications of rheological assumptions and validate this approach through comparison to experiments of both frictional and fluidized flows made of glass beads (Sauter mean grain‐size of 75 μm). Because the rheology of highly polydisperse, highly angular, polydensity granular mixtures is poorly known, we focus on simplified monodisperse or bidisperse mixtures described by the frictional flow theory of Schaeffer (1987, https://doi.org/10.1016/0022-0396(87)90038-6) and Srivastava‐Sundaresan, often referred to as the Princeton model (Srivastava & Sundaresan, 2003, https://doi.org/10.1016/S0032-5910(02)00132-8). We show that simulations including the latter model replicate well the flow shape, kinematics, and pore fluid pressure that match well‐constrained dam‐break experiments of initially fluidized or pressure‐balanced granular flows. Simulations reveal that pore fluid pressure is intrinsically modulated by dilation and compaction of the flow and hence can be generated in concentrated pyroclastic density currents. We use these simulations to interpret basal pore pressure signals from local flow properties (mixture density, solid velocity, and pore fluid pressure). Rheological changes retard these simulated flows considerably near the predicted runout, but most continuum models cannot inherently predict a zero velocity. We suggest an inertial number parameter that can be used to approximate deposition, and this approach could be a valuable tool used to validate simulations against natural pyroclastic current examples.

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Section: Resultsmentioning

confidence: 99%

Continuum Modeling of Pressure‐Balanced and Fluidized Granular Flows in 2‐D: Comparison With Glass Bead Experiments and Implications for Concentrated Pyroclastic Density Currents

2019

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“…They consist of a dense hot mixture of solid particles and volcanic gases, which is overridden by a dilute turbulent ash cloud [ Druitt , , Branney and Kokelaar , 2002, Sulpizio et al ., ; Dufek , ]. Pyroclastic flows can propagate in a fluid‐like manner, and the largest flows may have velocities of tens of meters per second and runout distances up to 100 km, even on subhorizontal slopes [ Roche et al ., ]. These flows can damage buildings and infrastructures, and they represent the first cause of death in volcanic environments [ Blong , ].…”

Section: Introductionmentioning

confidence: 99%

Effects of pore pressure in pyroclastic flows: Numerical simulation and experimental validation

Gueugneau

Kelfoun

Roche

et al. 2017

Geophysical Research Letters

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Pyroclastic flows are mixtures of volcanic gases and particles that can be very hazardous owing to their fluid‐like behavior. One possible mechanism to explain this behavior is the reduction of particles friction due to the internal gas pore pressure. To verify this hypothesis, we present a numerical model of a granular flow with high initial pore pressure that decreases with time as the gas‐particle mixture propagates. First, we validate the model by reproducing laboratory experiments. Then, the numerical code is applied to pyroclastic flows of Lascar volcano (1993 eruption, Chile). The simulation reproduces the runout and the morphological features of the deposits, with lateral levées, a central channel, and a lobate front. Our results support the hypothesis of the role of gas pore pressure in pyroclastic flows and explain both the fluid‐like behavior of the flows and the formation of lateral levees.

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“…Estimations of Mass Eruption Rates (MERs) obtained with different independent methods (Wilson and Walker, 1981;Hildreth and Mahood, 1986;Wilson and Hildreth, 1997;Baines and Sparks, 2005;Costa et al, 2014;Martí et al, 2016;Roche et al, 2016) indicate MERs of the orders 10 9 -10 11 kg/s (e.g., Bishop Tuff, Campanian Ignimbrite, Oruanui eruption, Taupo eruption, Peach Spring Tuff, Young Toba Tuff), implying durations of few to several hours only to evacuate even thousands of km 3 of magma.…”

Section: Introductionmentioning

confidence: 99%

Stress Field Control during Large Caldera-Forming Eruptions

Costa

Martı́

2016

Front. Earth Sci.

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Crustal stress field can have a significant influence on the way magma is channeled through the crust and erupted explosively at the surface. Large Caldera Forming Eruptions (LCFEs) can erupt hundreds to thousands of cubic kilometers of magma in a relatively short time along fissures under the control of a far-field extensional stress. The associated eruption intensities are estimated in the range 10 9 -10 11 kg/s. We analyse syn-eruptive dynamics of LCFEs, by simulating numerically explosive flow of magma through a shallow dyke conduit connected to a shallow magma (3-5 km deep) chamber that in turn is fed by a deeper magma reservoir (>∼10 km deep), both under the action of an extensional far-field stress. Results indicate that huge amounts of high viscosity silicic magma ( 10 7 > Pa s) can be erupted over timescales of a few to several hours. Our study provides answers to outstanding questions relating to the intensity and duration of catastrophic volcanic eruptions in the past. In addition, it presents far-reaching implications for the understanding of dynamics and intensity of large-magnitude volcanic eruptions on Earth and to highlight the necessity of a future research to advance our knowledge of these rare catastrophic events.

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Slow-moving and far-travelled dense pyroclastic flows during the Peach Spring super-eruption

Cited by 82 publications

References 31 publications

Continuum Modeling of Pressure‐Balanced and Fluidized Granular Flows in 2‐D: Comparison With Glass Bead Experiments and Implications for Concentrated Pyroclastic Density Currents

Continuum Modeling of Pressure‐Balanced and Fluidized Granular Flows in 2‐D: Comparison With Glass Bead Experiments and Implications for Concentrated Pyroclastic Density Currents

Effects of pore pressure in pyroclastic flows: Numerical simulation and experimental validation

Stress Field Control during Large Caldera-Forming Eruptions

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