Marie Chaput
Institut de Physique du Globe de Paris
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Publication
Featured researches published by Marie Chaput.
Journal of Geophysical Research | 2014
Marie Chaput; Vincent Famin; Laurent Michon
We performed a microstructural study of Piton des Neiges (La Reunion Island) to understand how intrusions and stresses control each other in basaltic volcanoes. Our study reveals that three perpendicular intrusions trends coexisted during the 2 Myr history of the volcano: a N120–140°E rift zone, a perpendicular dike trend, and swarms of subhorizontal intrusions hereafter called “sill zones”. Independently, the inversion of fault-slip data shows that incompatible paleostress fields recurrently occurred along with the intrusions: a dominant NNE-SSW extension, a perpendicular extension, and strike-slip or compressional regimes. The orientations of paleostresses are consistent with the orientations of the three perpendicular intrusion populations. We propose that stress accumulation in the edifice under the effect of repeated magma injections resulted in permutations of the principal axes of the stress tensor, causing a reorientation of subsequent intrusions. Stress permutations were cyclical. Each cycle started with dike injections in an extensional stress field, reducing the deviatoric stress and switching the axes of principal stresses, and finished with sill intrusions in a compressional stress field. Sill zones acted as detachment planes, restoring the extensional stress field and initiating a new cycle of permutations. Our model of stress permutations is in agreement with the pattern of eruptions and deformation observed at Piton de la Fournaise. In contrast with the Hawaiian model of spreading on a decollement, stress permutations in La Reunions volcanoes imply that the basal deformation of the edifices, if any, is not sufficient to compensate the reduction of deviatoric stress caused by intrusions.
Geophysical Research Letters | 2014
Marie Chaput; Virginie Pinel; Vincent Famin; Laurent Michon; Jean-Luc Froger
Sheared sills are observed at Piton des Neiges (the eroded basaltic volcano of La Reunion) 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.
Journal of Geophysical Research | 2014
Valérie Cayol; Thibault Catry; Laurent Michon; Marie Chaput; Vincent Famin; Olivier Bodart; Jean-Luc Froger; Claudia Romagnoli
Field work carried out on the Piton des Neiges volcano (Reunion 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.
Journal of Volcanology and Geothermal Research | 2012
Stéphanie Barde-Cabusson; Anthony Finizola; Aline Peltier; Marie Chaput; N. Taquet; Stéphanie Dumont; Zacharie Duputel; Alexandra Guy; Lucie Mathieu; S. Saumet; F. Sorbadère; M. Vieille
Journal of Volcanology and Geothermal Research | 2009
Stéphanie Barde-Cabusson; G. Levieux; Jean-François Lénat; Anthony Finizola; A. Revil; Marie Chaput; Stéphanie Dumont; Zacharie Duputel; Alexandra Guy; Lucie Mathieu; S. Saumet; F. Sorbadère; M. Vieille
Journal of Volcanology and Geothermal Research | 2016
Elodie Brothelande; Jean-François Lénat; Marie Chaput; Lydie Gailler; Anthony Finizola; Stéphanie Dumont; Aline Peltier; Patrick Bachèlery; Stéphanie Barde-Cabusson; Svetlana Byrdina; Patrick Menny; Julien Colonge; Guilhem Amin Douillet; Jean Letort; Ludovic Letourneur; Olivier Merle; F. Di Gangi; David Nakedau; Esline Garaebiti
Journal of Geodynamics | 2016
Vincent Famin; Carole Berthod; Laurent Michon; Julia Eychenne; Elodie Brothelande; Marie-Myriam Mahabot; Marie Chaput
Tectonophysics | 2017
Marie Chaput; Vincent Famin; Laurent Michon
Archive | 2017
Marie Chaput; Vincent Famin; Laurent Michon
Journal of Geophysical Research | 2014
Marie Chaput; Vincent Famin; Laurent Michon