and numerical modeling
Laboratoire Géosciences Réunion - IPGP Université de la Réunion 15, Avenue René Cassin, BP 7151 97715 Saint Denis messagerie cedex 9 La Réunion phone: (33) 02 62 93 82 10 fax: (33) 02 62 93 82 6
PhD student from October 2009 to April 2013, La Reunion University
Thesis: Deformation and intrusive activity on basaltic shield volcanoes - From field work to numerical modeling (Piton des Neiges, La Réunion Island)
Advisors: Laurent Michon and Vincent Famin
Basaltic shield volcanoes deform under their own weight, especially during eruptive periods. In Hawaii, this co-eruptive deformation is mainly explained by slip events on a basal decollement plane, related to the forceful intrusion of magma into “rift zones” (i.e. high concentration of subvertical dikes in weakness areas). However, this explanation is not valid on many other basaltic shields where the existence of basal decollements is unlikely.
We used the deep incision of Piton des Neiges volcano (La Réunion) to observe the internal structure of a basaltic shield. By coupling a field work and a numerical study, we aimed at understand how deformation interacts with magmatic activity on such an edifice. Our structural study reveals that three populations of perpendicular intrusions coexist and that the main weakness areas are “sill zones” (i.e. high concentration of low-dipping intrusions). In parallel, our study of brittle deformation structures shows that two perpendicular extensional stress fields dominate in the edifice and that strike-slip and compressional regimes appear near sill zones. The directions of deformation are compatible with the orientations of intrusions and are also consistent with the directions of emplacement of large debris avalanches, which occurred on Piton des Neiges during its evolution. From these field data, we propose a deformation model of Piton des Neiges volcano where magma intrusion in the edifice generates cycles of stress permutations. The ultimate stage of each cycle consists in sill intrusion under a compressional regime. The numerical simulations, testing the influence of such injections on edifice deformation, reveal that sills can be major instability factors, capable of triggering large flank collapses. Our conceptual model, inferred from field work and quantified by numerical models, thus constitutes an alternative to the Hawaiian model of deformation, applicable on edifices like Piton de la Fournaise (La Réunion), Tenerife (Canary) or Fernandina (Galapagos). Our study finally demonstrates the essential interest of studying old eroded systems to understand active volcanoes.
- 2009-2013 PhD in Volcanology, Laboratoire GéoSciences Réunion, La Réunion University
- 2008-2009 Master's degree in Earth Sciences (2nd year), Laboratoire Magmas et Volcans - Blaise Pascal University, Clermont-Ferrand.
Thesis: Geoelectrical study of the Yasur volcano and Yenkahe horst, Tanna Island, Vanuatu. Volcanic, volcano-tectonic and hydrothermal fields.
Advisors: Anthony Finizola and Jean-François Lénat
2007-2008 Master's degree in Earth Sciences (1st year), Laboratoire GéoSciences Réunion, La Réunion University
Thesis: Significance of installing a continuous SP monitoring network on the Piton de la Fournaise summit, Reunion Island.
Advisor: Anthony Finizola
2009-2013 : Structural investigations and mapping of the inner structure of Piton des Neiges volcano
January 2010 : Oceanographic cruise ERODER-4, in the surroundings of La Reunion Island. Coring and sampling of the submarine part of the island and the surrounding plate.
July 2008: Geophysical field campaign at Yasur volcano (Tanna Island, Vanuatu). Geophysical study of Yasur-Yenkahe dome complex. Acquisition of electromagnetic (ERT and TDEM), geoelectrical (SP), and gravimetric data. ANR Project « Arc-Vanuatu », financed by ANR CATELL 2006.
Feb-May 2007 : Self-potential (SP) survey of the summital part of Piton de la Fournaise volcano.
August 2006: Field campaign at Piton de la Fournaise volcano, Reunion Island. Hydrothermal system study of Piton de la Fournaise by Self-Potential (SP) survey.
June 2005 : Field campaign at Stromboli volcano (Italy). Self-Potential (SP), soil gases (CO2) and thermometry.
2012-2013 : Lecturer - Department of Earth Sciences, La Réunion University. B.S and M.S level.
Disciplines: Introduction to Earth Sciences, Structural geology, Tectonics, Magmatic and metamorphic petrology, Earth history and evolution, field trips.
- Chaput, M., V. Pinel, V. Famin, L. Michon, and J.-L. Froger, 2014. Co-intrusive shear displacement by sill intrusion in a detachment: a numerical approach, Geophysical Research Letters, accepted.
- Chaput, M., V. Famin, and L. Michon, 2014. Deformation of basaltic shield volcanoes under co-intrusive stress permutations, Journal of Geophysical Research - Solid Earth, 119, doi: 10.1002/2013JB010623.
Barde-Cabusson S., Finizola A., Peltier A., Chaput M., Taquet N., Dumont S., Duputel Z.,Guy A., Mathieu L., Saumet S., Sorbadère F., Vieille M. 2012. Structural control of collapse events inferred by self-potential mapping on the Piton de la Fournaise volcano (La Réunion Island). J. Volcanol. Geotherm. Res., 209-210, 9-18. doi: 10.1016/j.jvolgeores.2011.09.014.
- Barde-Cabusson, S., Levieux, G., Lénat, J.-F., Finizola A., Revil, A., Chaput, M., Dumont, S., Duputel, Z., Guy, A., Mathieu, L., Saumet, S., Sorbadère, F. and Vieille, M., 2009. Transient self-potential anomalies associated with recent lava flows at Piton de la Fournaise volcano (Réunion Island, Indian Ocean). J. Volcanol. Geotherm. Res., vol. 187, 3-4, 158-166.
Articles in preparation
Cayol, V., T. Catry, L. Michon, M. Chaput, V. Famin, J.-L. Froger, and C. Romagnoli (2014), Sheared sheet intrusions as a trigger for lateral flank failure on basaltic volcanoes, in prep. Submission to Journal of Volcanology and Geothermal Research.
- Chaput, M., V. Famin and L. Michon (2012). Sill zones and stress permutations: an alternative to the Hawaiian model of basaltic volcano deformation. AGU Chapman Conference on Hawaiian volcanoes 2012, Hawaii, USA.
- Famin, V., M. Chaput, and L., Michon (2012). An unified model for the deformation of basaltic volcanoes. AGU Chapman Conference on Hawaiian volcanoes – Hawaii, USA – 19-24th August 2012.
- M., Chaput, V., Famin, L., Michon and T., Catry (2010). Large-scale destabilization of a basaltic shield volcano (Piton des Neiges volcano, La Réunion Island). 3rd Collapse Caldera Workshop (CCW) 2010, La Réunion Island. (Talk)
- Catry, T., V., Cayol, L., Michon, M., Chaput, V., Famin and C., Romagnoli (2010). Co-intrusive shear stress triggers flank collapse on basaltic volcanoes. 3rd Collapse Caldera Workshop (CCW) 2010, La Réunion Island. (Poster)
- M., Chaput, V., Famin, L., Michon and T., Catry (2010). Long term dismantling of a basaltic volcano (Piton des Neiges, La Réunion hotspot). EGU 2010, in Geophysical Research Abstracts 12, EGU2010-7726, Vienna, Austria. (Poster).
- Catry, T. V. Cayol, L. Michon, V. Famin, C. Romagnoli, M. Chaput (2010). Dikes and sills, what is the most likely trigger of volcano flank collapse? EGU 2010, in Geophysical Research Abstracts 13, EGU2010-7512, Vienna, Austria.
- Chaput, M., Dumont, S., Lénat, J.-F., Finizola, A., Gailler, L., Barde-Cabusson, S., Byrdina, S., Menny, P., Peltier, A., Colonge, J., Douillet, G., Letort, J., Bachèlery, P., Nakedau, D., Garaebiti, E. Structure and Hydrothermal System of Yasur volcano (Vanuatu archipelago) inferred from Gravimetry, Electric Resistivity Tomography, Time Domain Electro-Magnetism, Self-Potential, subsurface Temperature and soil CO2 concentration. STAR meeting, SOPAC Annual session, Port Vila (Vanuatu), 21-24 October 2009. Abstract & poster.
- Carole Berthod, M.S.1 (2011)