Cointrusive shear displacement by sill intrusion in a detachment: A numerical approach

Chaput, Marie; Pinel, Virginie; Famin, Vincent; Michon, Laurent; Froger, Jean‐Luc

doi:10.1002/2013gl058813

Cited by 31 publications

(30 citation statements)

References 22 publications

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“…On the other hand, events being located in a very limited depth range (±50 m around a east dipping plane), we cannot totally rule out the possibility that seismicity is triggered on a single slowly slipping plane. Such slow slip process has been observed on other volcanoes [ Cervelli et al , ; Segall et al , ] and might involve a subhorizontal detachment such as observed during the April 2007 Piton de la Fournaise eruption [ Got et al , ; Chaput et al , ; Froger et al , ]. To better understand the physical process driving the shallow seismicity, we are currently working on inferring focal mechanisms of shallow earthquakes.…”

Section: Discussionsupporting

confidence: 89%

Uncovering the hidden signature of a magmatic recharge at Piton de la Fournaise volcano using small earthquakes

Lengliné

Duputel

Ferrazzini

2016

Geophysical Research Letters

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We apply a template matching method to detect and locate preeruptive earthquakes at Piton de la Fournaise volcano in 2014 and 2015. This approach enabled the detection of many events and unveiled persistent seismicity features through multiple eruptions. Shallow earthquakes define a ring‐shaped structure beneath the main crater. The repetitive occurrence of events along this structure suggests that it corresponds to a preexisting zone of weakness within the edifice. We also show evidence of deep magma transfer in 2015. More than 5000 deep earthquakes define an upward migration immediately followed by the occurrence of shallow events leading to an eruption 20 days later. This suggests the creation of a hydraulic connection between the lower part of the volcanic system and a magma reservoir located near sea level. We can envisage than such replenishments of the shallow reservoir occurred in the past but were undetected because of limited deep earthquake detections.

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Section: Discussionsupporting

confidence: 89%

Uncovering the hidden signature of a magmatic recharge at Piton de la Fournaise volcano using small earthquakes

Lengliné

Duputel

Ferrazzini

2016

Geophysical Research Letters

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“…subvertical σ 3 ) would be attained by horizontal stress accumulation under the effect of recurrent dyke injections along the rift zones, and the subsequent permutations of the principal stress tensors, as evidenced for Piton des Neiges volcano, the inactive twin of Piton de la Fournaise. In such an evolution, sills act as detachment planes, restoring the extensional stress field (Famin and Michon, 2010;Chaput et al, 2014aChaput et al, , 2014b.…”

Section: Summit and Outer Rift Zones Related To The Shallow Plumbing mentioning

confidence: 99%

Rift zones and magma plumbing system of Piton de la Fournaise volcano: How do they differ from Hawaii and Etna?

Michon

Ferrazzini

Muro

et al. 2015

Journal of Volcanology and Geothermal Research

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122

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International audienceOn ocean basaltic volcanoes, magma transfer to the surface proceeds by subvertical ascent from the mantle lithosphere through the oceanic crust and the volcanic edifice, possibly followed by lateral propagation along rift zones. We use a 19-year-long database of volcano-tectonic seismic events together with detailed mapping of the cinder cones and eruptive fissures to determine the geometry and the dynamics of the magma paths intersecting the edifice of Piton de la Fournaise volcano. We show that the overall plumbing system, from about 30 km depth to the surface, is composed of two structural levels that feed distinct types of rift zones. The deep plumbing system is rooted between Piton des Neiges and Piton de la Fournaise volcanoes and has a N30–40 orientation. Above 20 km below sea level (bsl), the main axis switches to a N120 orientation, which permits magma transfer from the lithospheric mantle to the base of the oceanic crust, below the summit of Piton de la Fournaise. The related NW-SE rift zone is 15 km wide, linear, spotted by small to large pyroclastic cones and related lava flows and emits slightly alkaline magmas resulting from high-pressure fractionation of clinopyroxene ± olivine. This rift zone has low magma production rate of ~ 0.5–3.6 × 10 −3 m 3 s −1 and an eruption periodicity of around 200 years over the last 30 ka. Seismic data suggest that the long-lasting activity of this rift zone result from regional NNE-SSW extension, which reactivates inherited lithospheric faults by the effect of underplating and/or thermal erosion of the mantle lithosphere. The shallow plumbing system (b11 km bsl) connects the base of the crust with the Central Cone. It is separated from the deep plumbing system by a relatively large aseismic zone between 8 and 11 km bsl, which may represent a deep storage level of magma. The shallow plumbing system feeds frequent, short-lived summit and flank (NE and SE flanks) eruptions along summit and outer rift zones, respectively. Summit rift zones are very active (~0.1–0.25 m 3 s −1), short (2–3 km), and present an orthogonal pattern confined to the central active cone of Piton de la Fournaise. Outer NE and SE rift zones are much less active (~4–7.3 × 10 −3 m 3 s −1) and extend from inside the Enclos Fouqué caldera to bound the mobile eastern volcano flank. We show that the outer rift zones are almost aseismic and are genetically linked to the seaward flank displacements, whose most recent events where detected in 2004 and 2007. East flank sliding is itself triggered by shallow (b 2 km depth) sill intrusions. We propose that the subvertical magma intrusions along the perpendicular summit rift zones, sill intrusions, and subsequent magma injections along the outer rift zones are controlled by cycles of stress permutations. We thus tentatively propose that as for Piton de la Fournaise, the regional stress field acting on Etna and Hawaiian volcanoes is an important parameter in the control of the magma transfer along their deep plumbing system whereas the dyna...

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“…Field studies have highlighted the presence of sills and laccoliths in volcanic complexes [e.g., Pasquare and Tibaldi , ; Burchardt , ]. Numerous geodetic surveys have also revealed the emplacement of sills, some of which resulting in eruptions, among others, in the Galápagos Islands [e.g., Amelung et al , ], Eyjafjallajökull volcano, Iceland [e.g., Pedersen and Sigmundsson , , ; Sigmundsson et al , ], in the Afar region, Ethiopia [e.g., Nobile et al , ; Pagli et al , ], and Piton de la Fournaise volcano, Réunion Island [e.g., Chaput et al , ].…”

Section: Introductionmentioning

confidence: 99%

Inelastic deformation during sill and laccolith emplacement: Insights from an analytic elastoplastic model

2017

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Numerous geological observations evidence that inelastic deformation occurs during sills and laccoliths emplacement. However, most models of sill and laccolith emplacement neglect inelastic processes by assuming purely elastic deformation of the host rock. This assumption has never been tested so that the role of inelastic deformation on the growth dynamics of magma intrusions remains poorly understood. In this paper, we introduce the first analytical model of shallow sill and laccolith emplacement that accounts for elastoplastic deformation of the host rock. It considers the intrusion's overburden as a thin elastic bending plate attached to an elastic‐perfectly plastic foundation. We find that, for geologically realistic values of the model parameters, the horizontal extent of the plastic zone lp is much smaller than the radius of the intrusion a. By modeling the quasi‐static growth of a sill, we find that the ratio lp/a decreases during propagation, as 1/a4ΔP, with ΔP the magma overpressure. The model also shows that the extent of the plastic zone decreases with the intrusion's depth, while it increases if the host rock is weaker. Comparison between our elastoplastic model and existing purely elastic models shows that plasticity can have a significant effect on intrusion propagation dynamics, with, e.g., up to a doubling of the overpressure necessary for the sill to grow. Our results suggest that plasticity effects might be small for large sills but conversely that they might be substantial for early sill propagation.

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Cointrusive shear displacement by sill intrusion in a detachment: A numerical approach

Cited by 31 publications

References 22 publications

Uncovering the hidden signature of a magmatic recharge at Piton de la Fournaise volcano using small earthquakes

Uncovering the hidden signature of a magmatic recharge at Piton de la Fournaise volcano using small earthquakes

Rift zones and magma plumbing system of Piton de la Fournaise volcano: How do they differ from Hawaii and Etna?

Inelastic deformation during sill and laccolith emplacement: Insights from an analytic elastoplastic model

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