Volcanic sintering: Timescales of viscous densification and strength recovery

Vasseur, Jérémie; Wadsworth, Fabian B.; Lavallée, Yan; Hess, Kai‐Uwe; Dingwell, Donald B.

doi:10.1002/2013gl058105

Cited by 97 publications

(95 citation statements)

References 39 publications

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“…2008; Vasseur et al, 2013;Wadsworth et al, 2014), it is yet to encompass the complexity of natural crystal-bearing magmas. Likewise, while such cycles lead to ample preservation of tuffisites in glassy deposits at the surface (e.g., Stasiuk et al, 1996;Tuffen and Dingwell, 2005;Castro et al, 2014) they are rarely recognized in crystal-bearing magmas (Kolzenburg et al, 2012).…”

Section: Magma Fragmentation and Tuffisite Formationmentioning

confidence: 99%

“…When Eo ≪ 1, the model described below can be used. Sintering of high viscosity liquid droplets, such as silicate melts at magmatic temperatures, have been found to scale with a characteristic timescale across a large range of viscosities (Vasseur et al, 2013;Wadsworth et al, 2014). This is the capillary timescale (τ) defined by Taylor (1934), that describes the relaxation of a droplet to a sphere under the excess surface stress exerted by interfacial tension and is dependent on the particle radius and the Newtonian melt viscosity µ via:…”

Section: Sintering Data Analysismentioning

confidence: 99%

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Blowing Off Steam: Tuffisite Formation As a Regulator for Lava Dome Eruptions

et al. 2016

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Tuffisites are veins of variably sintered, pyroclastic particles that form in conduits and lava domes as a result of localized fragmentation events during gas-and-ash explosions. Those observed in-situ on the active 2012 lava dome of Volcán de Colima range from voids with intra-clasts showing little movement and interpreted to be failure-nuclei, to sub-parallel lenses of sintered granular aggregate interpreted as fragmentation horizons, through to infilled fractures with evidence of viscous remobilization. All tuffisites show evidence of sintering. Further examination of the complex fracture-and-channel patterns reveals viscous backfill by surrounding magma, suggesting that lava fragmentation was followed by stress relaxation and continued viscous deformation as the tuffisites formed. The natural tuffisites are more permeable than the host andesite, and have a wide range of porosity and permeability compared to a narrower window for the host rock, and gaging from their significant distribution across the dome, we posit that the tuffisite veins may act as important outgassing pathways. To investigate tuffisite formation we crushed and sieved andesite from the lava dome and sintered it at magmatic temperatures for different times. We then assessed the healing and sealing ability by measuring porosity and permeability, showing that sintering reduces both over time. During sintering the porosity-permeability reduction occurs due to the formation of viscous necks between adjacent grains, a process described by the neck-formation model of Frenkel (1945). This process leads the granular starting material to a porosity-permeability regime anticipated for effusive lavas, and which describes the natural host lava as well as the most impervious of natural tuffisites. This suggests that tuffisite formation at Volcán de Colima constructed a permeable network that enabled gas to bleed passively from the magma. We postulate that this progressively reduced the lava dome's ability to seal and build pressure that drives explosions. Indeed, the time interval between explosions during 2007-2011 gradually increased before the onset of a period of quiescence starting in June 2011. We suggest that the permeability evolution during tuffisite formation has important consequences for modeling of gas-and-ash explosions, common at dome-forming volcanoes.

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Section: Magma Fragmentation and Tuffisite Formationmentioning

confidence: 99%

Section: Sintering Data Analysismentioning

confidence: 99%

Blowing Off Steam: Tuffisite Formation As a Regulator for Lava Dome Eruptions

et al. 2016

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“…These include planetesimal formation [1], welding in shallow volcanic interiors [2][3][4], formation of deposits of large meteorite impacts and volcanic supereruptions [5], adhesion of volcanic ash in commercial jet engines [6,7], and industrial fabrication of ceramics and glasses [8][9][10][11]. In most sintering scenarios of practical interest, the viscosity of the droplets is high and the droplets are small, such that the Ohnesorge and Eötvös numbers are high and low, respectively.…”

Section: Introductionmentioning

confidence: 99%

Topological inversions in coalescing granular media control fluid-flow regimes

et al. 2017

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“…In this case, models for the effect of spherical cavities on the stress required for fracturing are valid and they predict that the stress is reduced significantly as the bulk gas volume fraction increases (Sammis and Ashby 1986). This has been confirmed in the high Deborah number regime for porous liquids analogous to volcanic systems (Vasseur et al 2013) but remains untested in the low Deborah number regime where bubble deformation may be important.…”

Section: Extensions To Multiphase Magmasmentioning

confidence: 86%

When Does Magma Break?

Wadsworth¹,

Witcher²,

Vasseur³

et al. 2017

Advances in Volcanology

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Geophysical signals arriving at the Earth's surface originate from a source mechanism at depth but are not necessarily directly observable. Therefore, well-posed experiments can provide insights into source mechanics and, importantly, the parameters required to model aspects of the sources of unrest signals. In this Chapter we detail one such example of how experimental laboratory work has improved our understanding of unrest signals. We focus on the failure of single-and multi-phase magmas, demonstrating that the liquid viscosity, and therefore the temperature and volatile content of a magma of a given composition, is the limiting parameter in determining whether a magma will ascend viscously or whether it can fracture during ascent. This critical threshold is characterized by a Deborah number, the ratio of the timescale of relaxation to the timescale of local flow. We show that for single-phase magmatic liquids and for vigorously vesiculating magmas, a local Deborah number of 10 À2 is the limit above which mixed viscoelastic behaviour including fracture propagation can be expected, and a Deborah number of 1 is the limit above which magma is dominantly elastic and responds in a brittle manner to applied stresses. These thresholds can be understood in terms of the onset and peak of the Debye relaxation process for viscoelastic liquids. The apparent validity of a Maxwell model permits us to predict the maximum stress that can be supported by a volcanic liquid deforming in the high Deborah number range. We use these constraints to provide a map of timescales on which we contour dominant system responses from viscous to purely brittle; valid for all magmatic liquids. Finally, we explore the scaling necessary to extend these conceptual insights to crystal-and bubble-bearing magmas valid under specific conditions. The competing timescales of deformation and relaxation in magma are relevant to unrest source mechanisms that originate from magma deformation, such as long-period seismic signals that are used to predict eruption timing. KeywordsRheology Á Strain rate Á Experimental volcanology Á Glass transition Á Failure forecasting Á Low frequency earthquakes Á Viscous dissipation Glossary RheologyThe study of the response of a material to an applied stress or deformation. In the volcano-sciences this typically refers to magma-rheology which is dominated by the rheology of the liquid phase (a viscous or viscoelastic melt) and the additional effect of suspended phases (crystals and gases). Viscoelasticity A material response to an applied stress in which both elastic and viscous components of the deformation are observed. In magma, as the temperature decreases or the local strain rate increases, the elastic component becomes more dominant. When the viscous component is negligible, purely elastic behaviour and material-rupture can readily occur. See Rheology.

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Volcanic sintering: Timescales of viscous densification and strength recovery

Cited by 97 publications

References 39 publications

Blowing Off Steam: Tuffisite Formation As a Regulator for Lava Dome Eruptions

Blowing Off Steam: Tuffisite Formation As a Regulator for Lava Dome Eruptions

Topological inversions in coalescing granular media control fluid-flow regimes

When Does Magma Break?

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