Deformation of basaltic shield volcanoes under cointrusive stress permutations

Chaput, Marie; Famin, Vincent; Michon, Laurent

doi:10.1002/2013jb010623

Cited by 30 publications

(39 citation statements)

References 131 publications

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“…The last known process that can be invoked to maintain a favourable stress field for dyking is the occurrence of a regional extension like in Iceland (Walker, 1993) or at Fuerteventura (Fernández et al, 2006). Chaput et al (2014a) recently showed from a thorough structural analysis carried out in Piton des Neiges that this volcano underwent a dominant NNE-SSW extension throughout its period of activity (i.e., between at least 2.2 and 0.03 Ma). The extension led to the development of a main N120-140 rift zone (Chevallier and Vatin-Perignon, 1982;Chaput et al, 2014a), parallel to the NW-SE rift zone and the South Volcanic Zone.…”

Section: Nw-se Rift Zone and South Volcanic Zone Related To The Deep mentioning

confidence: 99%

“…Chaput et al (2014a) recently showed from a thorough structural analysis carried out in Piton des Neiges that this volcano underwent a dominant NNE-SSW extension throughout its period of activity (i.e., between at least 2.2 and 0.03 Ma). The extension led to the development of a main N120-140 rift zone (Chevallier and Vatin-Perignon, 1982;Chaput et al, 2014a), parallel to the NW-SE rift zone and the South Volcanic Zone. Moreover, our data reveal that the VT seismicity is not restricted to the massif of Piton de la Fournaise but also develops at the scale of La Réunion edifice (Fig.…”

Section: Nw-se Rift Zone and South Volcanic Zone Related To The Deep mentioning

confidence: 99%

“…Such displacements are interpreted as resulting from outward dipping sill injections below the eastern flank of the edifice (Tinard, 2007;Famin and Michon, 2010;Clarke et al, 2013;Di Muro et al, 2014;Froger et al, 2015). According to Chaput et al (2014a), in the lack of décollement level within the edifice or at the crust/edifice interface, the favourable stress conditions to permit sill intrusions (i.e. 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.…”

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

confidence: 99%

“…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%

“…At the surface, rift zones manifest themselves by the localisation of cinder cones, pit craters, and eruptive fissures, which results from the long-term (millennia) eruptive history of the volcano. The wide range of their geometry, from radial or circumferential diffuse rift zones (e.g., Etna, Galapagos; Chadwick and Dieterich, 1995;Neri et al, 2005) to narrow km-long rift zones (e.g., Hawaiian shields; Walker, 1999) is known to depend, among other parameters, on the dynamics of the plumbing system, the deformation of the volcanic edifice, and the structure of the crust underneath (MacDonald, 1972;Dieterich, 1988;Chadwick and Dieterich, 1995;Walker, 1999;Walter and Troll, 2003;Michon et al, 2007;Chaput et al, 2014a). For the world's most active basaltic volcanoes, such as Kilauea and Etna, the rift zones are well identified, correspond to the upper boundary of flank displacements ( Fig.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Nw-se Rift Zone and South Volcanic Zone Related To The Deep mentioning

confidence: 99%

Section: Nw-se Rift Zone and South Volcanic Zone Related To The Deep mentioning

confidence: 99%

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

confidence: 99%

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

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Chaput

Pinel

Famin

et al. 2014

Geophys. Res. Lett.

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Sheared sills are observed at Piton des Neiges (the eroded basaltic volcano of La Réunion) and are a suspected cause of the coeruptive flank displacement of Piton de la Fournaise in 2007. We performed a 2-D numerical study to quantify the perturbation induced by sill injection within a volcanic edifice. Magma is considered as an inviscid and pressurized fluid injected in an initially stable edifice under gravity-controlled extension. Two cases of injection are tested, in an elastic homogeneous edifice or along a detachment controlled by a friction law. We show that sill injection induces tangential displacements. This effect is strongly increased when sills are emplaced along a detachment, producing extension behind the injection and potentially ending in a large-scale flank collapse. Sill injections can thus explain the cointrusive shear deformation observed at Piton des Neiges and the tangential displacements measured at Piton de la Fournaise in 2007.

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Sheared sheet intrusions as mechanism for lateral flank displacement on basaltic volcanoes: Applications to Réunion Island volcanoes

et al. 2014

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Field work carried out on the Piton des Neiges volcano (Réunion Island) suggests that the injection of magma along detachments could trigger flank failure by conjugate opening and shear displacement. We use 3-D numerical models to compare the ability of purely opened sheet intrusions, sheared sheet intrusions, and normal faults to induce flank displacement on basaltic volcanoes. We assume that shear stress change on fractures results from stress anisotropy of the host rock under gravity. Exploring a large range of stress anisotropies, fracture dips, and fracture depth over length ratios, we determine that the amount of shear displacement is independent of the proximity to the ground surface. Sheared sheet intrusions are the most efficient slip medium on volcanoes. Consequently, the largest flank displacement is induced by the longest, deepest sheared intrusion dipping closest to 45°in a host rock with the highest stress anisotropy. Using our model in a forward way, we provide shear and normal displacements for buried fractures. Applying the model to a pile of sills at the Piton des Neiges volcano, we determine that the mean shear displacement caused by each intrusion was 3.7 m, leading to a total of a 180-260 m of lateral displacement for the 50 m high pile of sills. Using our model in an inverse way, we formulate a decision tree to determine some fracture characteristics and the host rock stress anisotropy from ratios of maximum surface displacements. This procedure provides a priori models, which can be used to bound the parameter space before it is explored through a formal inversion. Applying the decision tree to the 1.4 m coeruptive flank displacement recorded at Piton de la Fournaise in 2007, we find that it probably originated from a shallow eastward dipping subhorizontal normal fault.

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Deformation of basaltic shield volcanoes under cointrusive stress permutations

Cited by 30 publications

References 131 publications

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

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

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

Sheared sheet intrusions as mechanism for lateral flank displacement on basaltic volcanoes: Applications to Réunion Island volcanoes

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