Experimental constraints on degassing and permeability in volcanic conduit flow

Burgisser, Alain; Gardner, James E.

doi:10.1007/s00445-004-0359-5

Cited by 126 publications

(130 citation statements)

References 36 publications

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“…These vesicles provide an indirect record of magma ascent conditions. A significant body of work has been aimed at using bubble number density and size distributions to constrain rates of eruptive magma ascent and the timing of gas exsolution (e.g., Mangan et al 1993;Cashman and Mangan 1994;Polacci et al 2003;Burgisser and Gardner 2005;Proussevitch et al 2007). Vesicle shape is another manifestation of magma ascent conditions, in particular bubble growth, coalescence, and shearing (e.g., Klug and Cashman 1996;Mangan and Cashmann 1996;Polacci et al 2003;Rust et al 2003;Okumura et al 2008;Wright and Weinberg 2009), and can therefore provide a valuable complement to conventional studies of pyroclast textures.…”

Section: Introductionmentioning

confidence: 99%

Relating vesicle shapes in pyroclasts to eruption styles

et al. 2013

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Vesicles in pyroclasts provide a direct record of conduit conditions during explosive volcanic eruptions. Although their numbers and sizes are used routinely to infer aspects of eruption dynamics, vesicle shape remains an underutilized parameter. We have quantified vesicle shapes in pyroclasts from fall deposits of seven explosive eruptions of different styles, using the dimensionless shape factor , a measure of the degree of complexity of the bounding surface of an object. For each of the seven eruptions, we have also estimated the capillary number, Ca, from the magma expansion velocity through coupled diffusive bubble growth and conduit flow modeling. We find that is smaller for eruptions with Ca 1 than for eruptions with Ca 1. Consistent with previous studies, we interpret these results as an expression of the relative importance of structural changes during magma decompression and bubble growth, such as coalescence and shape relaxation of bubbles by capillary stresses. Among the samples analyzed, Strombolian and Hawaiian fire-fountain eruptions have Ca 1, in contrast to Vulcanian, Plinian, and ultraplinian eruptions. Interestingly, the basaltic Plinian eruptions of Tarawera volcano, New Zealand in 1886 and Mt. Etna, Italy in 122 BC, for which the cause of intense explosive activity has

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Section: Introductionmentioning

confidence: 99%

Relating vesicle shapes in pyroclasts to eruption styles

et al. 2013

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“…The products of these lower pressure runs also have more distorted and elongated bubbles, as opposed to the smaller rounded ones at higher pressures. Burgisser and Gardner (2004) (Burgisser and Gardner, 2004). In our runs, the rhyodacite charges did not contain an added fluid, and so collapse could occur.…”

Section: Decompression Experimentsmentioning

confidence: 72%

“…Most recently, Burgisser and Gardner (2004) found a threshold at ~40 vol.%. In addition, Burgisser and Gardner (2004) found that the onset of permeability is not instantaneous, but takes on order of 180 seconds when high-silica rhyolite reaches that threshold. Those 180 seconds likely represent the amount of time required for complete networks of bubbles to connect.…”

Section: Degassing During Magma Ascent In the Conduitmentioning

confidence: 99%

Section: Degassing During Magma Ascent In the Conduitmentioning

confidence: 99%

“…Some studies suggest that wide-scale permeability occurs when porosity reaches a porosity threshold (Eichelberger et al, 1986;Westrich and Eichelberger, 1994;Blower, 2001;Burgisser and Gardner, 2004). Most recently, Burgisser and Gardner (2004) found a threshold at ~40 vol.%. In addition, Burgisser and Gardner (2004) found that the onset of permeability is not instantaneous, but takes on order of 180 seconds when high-silica rhyolite reaches that threshold.…”

Section: Degassing During Magma Ascent In the Conduitmentioning

confidence: 99%

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Experimental and model constraints on degassing of magma during ascent and eruption

Gardner¹,

Burgisser²,

Hort³

et al. 2006

Neogene-Quaternary Continental Margin Volcanism: A Perspective From Me´xico

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Surface volcanic gases may reflect volatile budgets of magma and forecast impending eruptions, and their release to the atmosphere may affect climate. The dynamics of magma degassing is complicated, however, by differences in the solubility, partitioning, and diffusion of the various volatiles, all of which can vary with pressure, temperature, and melt composition. To constrain possible gas outputs, we carried out experiments to determine how Cl partitions between water bubbles and silicate melt, and decompression experiments to examine how Cl behaves duringclosed-and open-system degassing. We incorporate our findings and those from the literature for CO 2 and S into a steady, isothermal, and homogeneous flow model to estimate fluxes of gases at the vent from ascending water-rich magma, assuming different scenarios for the onset and development of permeability in bubbly magma. We find that, for given permeability scenarios, total gas fluxes vary with magma flux, but ratios of gas species do not change. The S/Cl and SO 2 /CO 2 ratios do change, however, depending on whether the magma is oxidized or reduced. After magma fragments into a Plinian eruption column gases continue to escape from cooling pumice in the plume, but here the rate of gas release is controlled by diffusion, which varies with temperature.Degassing of pumice and ash was modeled by linking a steady-state plume model, which gives the vertical variation of mean temperature and velocity of particles inside the plume, to a conductive cooling model of pumices, which controls diffusion of Cl, CO 2 , and S in pumice. We find that gas loss increases with column height (mass flux) and initial temperature, because in both cases pumices cool over a longer time period, allowing more gas to diffuse out of the matrix glass. The amount of gas released also depends on the size distribution of particles in the erupting mixture, with less being released for a finely skewed distribution.

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A new bubble dynamics model to study bubble growth, deformation, and coalescence

Huber

Nguyen

et al. 2014

JGR Solid Earth

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We propose a new bubble dynamics model to study the evolution of a suspension of bubbles over a wide range of vesicularity, and that accounts for hydrodynamical interactions between bubbles while they grow, deform under shear flow conditions, and exchange mass by diffusion coarsening. The model is based on a lattice Boltzmann method for free surface flows. As such, it assumes an infinite viscosity contrast between the exsolved volatiles and the melt. Our model allows for coalescence when two bubbles approach each other because of growth or deformation. The parameter (disjoining pressure) that controls the coalescence efficiency, i.e., drainage time for the fluid film between the bubbles, can be set arbitrarily in our calculations. We calibrated this parameter by matching the measured time for the drainage of the melt film across a range of Bond numbers (ratio of buoyancy to surface tension stresses) with laboratory experiments of a bubble rising to a free surface. The model is then used successfully to model Ostwald ripening and bubble deformation under simple shear flow conditions. The results we obtain for the deformation of a single bubble are in excellent agreement with previous experimental and theoretical studies. For a suspension, we observe that the collective effect of bubbles is different depending on the relative magnitude of viscous and interfacial stresses (capillary number). At low capillary number, we find that bubbles deform more readily in a suspension than for the case of a single bubble, whereas the opposite is observed at high capillary number.

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Experimental constraints on degassing and permeability in volcanic conduit flow

Cited by 126 publications

References 36 publications

Relating vesicle shapes in pyroclasts to eruption styles

Relating vesicle shapes in pyroclasts to eruption styles

Experimental and model constraints on degassing of magma during ascent and eruption

A new bubble dynamics model to study bubble growth, deformation, and coalescence

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