Energy consumption by magmatic fragmentation and pyroclast ejection during Vulcanian eruptions

Alatorre‐Ibargüengoitia, M. A.; Scheu, Bettina; Dingwell, Donald B.; Delgado-Granados, Hugo; Taddeucci, Jacopo

doi:10.1016/j.epsl.2009.12.051

Cited by 69 publications

(73 citation statements)

References 34 publications

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“…Departures from this trend, however, exist if a well-connected pore network efficiently releases pore pressure and reduces the energy available to achieve complete fragmentation (Mueller et al 2005;Mueller 2007). Whilst the process of fragmentation depends on the energy stored in the pore space, the ejection of the fragmented pyroclasts and the progression of an explosive eruption require additional stored energy, transformed into kinetic energy after fragmentation (Alatorre-Ibargüengoitia et al 2010). In other words, the pressure available to drive the ejection of ballistics (P ef ) equals the initial pressure stored in the pore fraction (P 0 ) minus the pressure required to fragment the porous magma (P th ):…”

Section: Fragmentation and Ballistic Ejectionmentioning

confidence: 99%

“…Colima (red diamond) best fits the criterion of Koyaguchi et al (2008) with S 3 =3.1. In contrast, the average of all volcanic material tends for S 3 =2 MPa (grey line; see Alatorre-Ibargüengoitia et al 2010). The superimposed porosity distribution reveals the material present in the conduit and helps constrain the overpressure required to initiate fragmentation.…”

Section: Eruption-style Transitionmentioning

confidence: 99%

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Magmatic architecture of dome-building eruptions at Volcán de Colima, Mexico

Lavallée¹,

Varley

Alatorre‐Ibargüengoitia

et al. 2011

Bull Volcanol

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Changes in the physical, chemical and rheological properties of ascending magma regulate the style of volcanic eruptions. Volcán de Colima's eruptive cycles of lava dome growth and explosions have been thoroughly monitored during the period 1998-2010 and provide a remarkable opportunity for deepening our understanding of the underlying processes responsible for the evolution of magma properties. Here, we integrate direct observation with analytical and experimental data to: (1) constrain the configuration of the shallow plumbing system and its influence on eruptive activity, (2) describe the rheological behaviour of the magma and (3) assess the conditions that lead to fragmentation and, ultimately, to explosive eruptions. The configuration of the shallow plumbing system was inferred from direct observation of extrusion sites and porosity of the erupted products. During the ongoing eruptive phase, magma was never extruded from a central vent: Both explosive and effusive activities were restricted to discrete vents inside the crater. Extensive field-based density measurements on 500 blocks in pyroclastic flow deposits reveal a bimodality of porosity at values of 12 and 26 vol.%. The least porous rocks tend to be altered, whereas the more porous rocks are pristine. This bimodal distribution, combined with the lack of a central vent, suggests the presence of a central, dense, altered plug, the fragments of which are entrained during explosive eruptions. During effusive periods, the plug appears to deflect the ascent of magma at a shallow depth and, consequently, the site of lava extrusion. The rheological properties and deformation-induced seismogenic behaviour of the magmas were investigated using a uniaxial deformation apparatus instrumented with acoustic sensors. The homogeneity in the physicochemical properties of the erupted magma permits the description of a flow law at eruptive temperature and strain rate conditions. The crystal-rich magma of Volcán de Colima exhibits a shear thinning rheology and becomes increasingly brittle at higher strain rates. Complete failure of magma can be predicted using the material failure forecast method, which integrates the acceleration of released acoustic energy throughout the deformation. Rapid decompression experiments of samples pressurised with argon were performed to assess the fragmentation conditions under which explosive eruptions progress. In the absence of gas loss due to permeable flow, the pore pressure required to fragment volcanic products is inversely proportional to the porosity. At Volcán de Colima, a rapid decompression of >6 MPa is required to fragment magma averaging 26 vol.% pores and to thereby instigate an explosive eruption. Analysis of ballistic impacts (4-6 km Editorial responsibility: M.A. Clynne

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Section: Fragmentation and Ballistic Ejectionmentioning

confidence: 99%

Section: Eruption-style Transitionmentioning

confidence: 99%

Magmatic architecture of dome-building eruptions at Volcán de Colima, Mexico

Lavallée¹,

Varley

Alatorre‐Ibargüengoitia

et al. 2011

Bull Volcanol

View full text Add to dashboard Cite

show abstract

“…The porosity of a rock controls the amount of gas stored and therefore the energy available for release during fragmentation for a given decompression step (Spieler et al, 2004;Alatorre-Ibargüengoitia et al, 2010). Earlier studies have defined the fragmentation threshold (the minimum pore pressure differential required to fully fragment the sample) as being inversely proportional to the porosity (Spieler et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Experimental constraints on phreatic eruption processes at Whakaari (White Island volcano)

Mayer

Scheu

Gilg

et al. 2015

Journal of Volcanology and Geothermal Research

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f Kakapo Disaster Resilience Trust, 2/48 Brockworth Place, Riccarton, Christchurch 8011, New Zealand a b s t r a c tVigorous hydrothermal activity interspersed by sequences of phreatic and phreatomagmatic eruptions occur at Whakaari (White Island volcano), New Zealand. Here, we investigate the influence of sample type (hydrothermally altered cemented ash tuffs and unconsolidated ash/lapilli) and fragmentation mechanism (steam flashing versus gas expansion) on fragmentation and ejection velocities as well as on particle-size and shape. Our rapid decompression experiments show that fragmentation and ejection speeds of two ash tuffs, cemented by alunite and amorphous opal, increase with increasing porosity and that both are significantly enhanced in the presence of steam flashing. Ejection speeds of unconsolidated samples are higher than ejection speeds of cemented tuffs, as less energy is consumed by fragmentation. Fragmentation dominated by steam flashing results in increased fragmentation energy and a higher proportion of fine particles. Particle shape analyses before and after fragmentation reveal that both steam flashing and pure gas expansion produce platy or bladed particles from fracturing parallel to the decompression front. Neither fragmentation mechanisms nor sample type show a significant influence on the shape. Our results emphasize that, under identical pressure and temperature conditions, eruptions accompanied by the process of liquid water flashing to steam are significantly more violent than those driven simply by gas expansion. Therefore, phase changes during decompression and cementation are both important considerations for hazard assessment and modeling of eruptions in hydrothermally active environments.

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“…As the purpose of this study is to calculate maximum horizontal ranges of VBPs, an initial pressure of 25 MPa is adopted which implies an overpressure towards the upper end of the range calculated by Burgisser et al (2011). This value is also higher than the initial pressure estimated for Popocatépetl volcano (11-13 MPa) and slightly higher than the one estimated for Colima volcano (19-22 MPa) (Alatorre-Ibargüengoitia et al, 2010).…”

Section: Quantitymentioning

confidence: 89%

“…First, a caprock model proposed by Alatorre-Ibargüengoitia et al (2010) approximating conditions during small volume explosive eruptions is used in order to estimate initial velocities of ejected VBPs. Initial velocities for higher energy eruptions are calculated by using an approach based on the conversion efficiency of thermal to kinetic energy (Sato and Taniguchi, 1997).…”

Section: Introductionmentioning

confidence: 99%

Maximum horizontal range of volcanic ballistic projectiles ejected during explosive eruptions at Santorini caldera

Konstantinou

2015

Journal of Volcanology and Geothermal Research

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Energy consumption by magmatic fragmentation and pyroclast ejection during Vulcanian eruptions

Cited by 69 publications

References 34 publications

Magmatic architecture of dome-building eruptions at Volcán de Colima, Mexico

Magmatic architecture of dome-building eruptions at Volcán de Colima, Mexico

Experimental constraints on phreatic eruption processes at Whakaari (White Island volcano)

Maximum horizontal range of volcanic ballistic projectiles ejected during explosive eruptions at Santorini caldera

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