The effect of edifice load on magma ascent beneath a volcano

Pinel, Virginie; Jaupart, Claude

doi:10.1098/rsta.2000.0601

Cited by 167 publications

(153 citation statements)

References 9 publications

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“…Initially, the stress gradient due to caldera collapse promotes the rise of magma (Fig.4a). In general, this may lead to post-caldera resurgence (Kennedy et al, 2012) and/or increased volcanism due to the decompression of a shallow reservoir that would favor the rise of magma from a deeper source if the reservoirs are hydraulically connected through a magmatic plumbing system (Pinel and Jaupart, 2000;Hooper et al, 2011). In case of significant unloading (Pl/Pe>5), the vertical orientation of σ3 beneath the caldera promotes shallow, flat-topped magma bodies (Fig.4b).…”

Section: Caldera Collapse Control On the Magma Plumbing Systemmentioning

confidence: 99%

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How caldera collapse shapes the shallow emplacement and transfer of magma in active volcanoes

Corbi

Rivalta

Pinel

et al. 2015

Earth and Planetary Science Letters

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Calderas are topographic depressions formed by the collapse of a partly drained magma reservoir. At volcanic edifices with calderas, eruptive fissures can circumscribe the outer caldera rim, be oriented radially and/or align with the regional tectonic stress field. Constraining the mechanisms that govern this spatial arrangement is fundamental to understand the dynamics of shallow magma storage and transport and evaluate volcanic hazard. Here we show with numerical models that the previously unappreciated unloading effect of caldera formation may contribute significantly to the stress budget of a volcano. We first test this hypothesis against the ideal case of Fernandina, Gal ‡pagos, where previous models only partly explained the peculiar pattern of circumferential and radial eruptive fissures and the geometry of the intrusions determined by inverting the deformation data. We show that by taking into account the decompression due to the caldera formation, the modeled edifice stress field is consistent with all the observations. We then develop a general model for the stress state at volcanic edifices with ! 1 calderas based on the competition of caldera decompression, magma buoyancy forces and tectonic stresses. These factors control: 1) the shallow accumulation of magma in stacked sills, consistently with observations; 2) the conditions for the development of circumferential and/or radial eruptive fissures, as observed on active volcanoes. This top-down control exerted by changes in the distribution of mass at the surface allows better understanding of how shallow magma is transferred at active calderas, contributing to forecasting the location and type of opening fissures.

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Section: Caldera Collapse Control On the Magma Plumbing Systemmentioning

confidence: 99%

“…The lateral growth of sill-like reservoirs is discouraged beyond the ! 11 caldera rim (Fig.4c), where the driving force of magma is reduced (Pinel and Jaupart, 2000).…”

Section: Caldera Collapse Control On the Magma Plumbing Systemmentioning

confidence: 99%

How caldera collapse shapes the shallow emplacement and transfer of magma in active volcanoes

Corbi

Rivalta

Pinel

et al. 2015

Earth and Planetary Science Letters

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“…It can change the emplacement depth of magmas. Pinel and Jaupart (2000) studied the influence of the gravitational stress on magma ascent and showed that a volcanic edifice can work as a magma filter that prevents the eruption of dense magmas. Their discussion was, however, based on the static criterion for a crack to extend (e.g., Watanabe et al, 1999).…”

Section: Influences Of Topographic Loadmentioning

confidence: 99%

Analog experiments on magma-filled cracks: Competition between external stresses and internal pressure

et al. 2014

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We have performed two series of analog experiments using gelatin to study the propagation of liquid-filled cracks in stressed medium. The first series was designed to study the competition between the external stress and the liquid excess pressure in controlling the propagation direction. We systematically controlled the external stress and the liquid excess pressure by changing the surface load and the liquid volume. An ascending crack progressively deflected to be perpendicular to the maximum tensile direction of the external stress. The degree of deflection depends on the ratio of the shear stress on a crack plane to the average liquid excess pressure. More deflection was observed for a crack with a larger ratio. No significant deflection was observed for the ratio less than 0.2. The volcanic activity in a compressional stress field might be understood in the context of this competition. The first series also demonstrated the importance of the gradient of the crack normal stress as a driving force for propagation. The vertical gradient of the gravitational stress generated by a mountain load can control the emplacement depth of magmas, and it might lead to the evolution of eruption style during the lifetime of a volcano. The second series was designed to study the three-dimensional interaction of two parallel buoyancy-driven cracks. The deflection of the second crack takes place, when the ratio of the shear stress generated by the first one to the average excess pressure of the second crack is larger than 0.2. If the second crack reaches the first one, the interaction can lead to the coalescence of two cracks. It has directivity: the region of coalescence extends more in the direction perpendicular to the first crack than in the direction parallel to it. It reflects the stress field around the first crack. This directivity might cause a characteristic spatial variation of magma chemistry through magma mixing.

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“…Multiple factors combining to generate such composite fields have been advocated and analyzed: loading due to the edifice (e.g., Dahm, 2000;Pinel and Jaupart, 2000;Maccaferri et al, 2011) and unloading (e.g., Maccaferri et al, 2014), the effects of volcano morphology (e.g., Tibaldi et al, 2014;Corbi et al, 2015), the generation of magma reservoirs and calderas (e.g., Tibaldi, 2015) and the anisotropy of host rocks (Gudmundsson, 2011a). Many dykes do not propagate all the way to the surface, but may be arrested by layers with variable associated stress (Gudmundsson and Philipp, 2006).…”

Section: Factors That Could Affect Stress and Strain In The Earsmentioning

confidence: 99%

Historical Volcanism and the State of Stress in the East African Rift System

et al. 2016

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Crustal extension at the East African Rift System (EARS) should, as a tectonic ideal, involve a stress field in which the direction of minimum horizontal stress is perpendicular to the rift. A volcano in such a setting should produce dykes and fissures parallel to the rift. How closely do the volcanoes of the EARS follow this? We answer this question by studying the 21 volcanoes that have erupted historically (since about 1800) and find that 7 match the (approximate) geometrical ideal. At the other 14 volcanoes the orientation of the eruptive fissures/dykes and/or the axes of the host rift segments are oblique to the ideal values. To explain the eruptions at these volcanoes we invoke local (non-plate tectonic) variations of the stress field caused by: crustal heterogeneities and anisotropies (dominated by NW structures in the Protoerozoic basement), transfer zone tectonics at the ends of offset rift segments, gravitational loading by the volcanic edifice (typically those with 1-2 km relief) and magmatic pressure in central reservoirs. We find that the more oblique volcanoes tend to have large edifices, large eruptive volumes, and evolved and mixed magmas capable of explosive behavior. Nine of the volcanoes have calderas of varying ellipticity, 6 of which are large, reservoir-collapse types mainly elongated across rift (e.g., Kone) and 3 are smaller, elongated parallel to the rift and contain active lava lakes (e.g., Erta Ale), suggesting different mechanisms of formation and stress fields. Nyamuragira is the only EARS volcano with enough sufficiently well-documented eruptions to infer its long-term dynamic behavior. Eruptions within 7 km of the volcano are of relatively short duration (<100 days), but eruptions with more distal fissures tend to have lesser obliquity and longer durations, indicating a changing stress field away from the volcano. There were major changes in long-term magma extrusion rates in 1977 (and perhaps in 2002) due to major along-rift dyking events that effectively changed the Nyamuragira stress field and the intrusion/extrusion ratios of eruptions.

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The effect of edifice load on magma ascent beneath a volcano

Cited by 167 publications

References 9 publications

How caldera collapse shapes the shallow emplacement and transfer of magma in active volcanoes

How caldera collapse shapes the shallow emplacement and transfer of magma in active volcanoes

Analog experiments on magma-filled cracks: Competition between external stresses and internal pressure

Historical Volcanism and the State of Stress in the East African Rift System

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