New geological and hydrogeological implications of the resistivity distribution inferred from audiomagnetotellurics over La Fournaise young shield volcano (Reunion Island)

M. Courteaud 1, * M. Ritz 2 B. Robineau 1 J.L. Join 1 J. Coudray 1
* Corresponding author
1 LGSR - Laboratoire GéoSciences Réunion
2 IRD Hann Maristes - Institut de recherche pour le développement [Dakar, Sénégal]
Abstract : An audiomagnetotelluric survey has been performed along an inactive flank of La Fournaise volcano massif in Reunion island, to study the subsurface resistivity structure. One-dimensional modelling of the AMT data at each site revealed an extensive low-resistivity (less than 10 ω m) zone at a few hundred meters below the surface. The significance of this unexpected conductive substratum is discussed in relation with the proposed impact of volcano-tectonic processes (caldera and landslides collapses), and a new interpretation of the geological structure is proposed. Moreover, it is likely that these conductors are poorly permeable argilaceous materials; then they coincide with a limit in permeability and determine groundwater behavior.
Keywords : Geoelectric structures Audiomagnetotellurics La Fournaise volcano Volcano-tectonic processes Groundwater Reunion Island
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Journal articles
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https://hal.univ-reunion.fr/hal-02100580
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Submitted on : Tuesday, April 16, 2019 - 9:45:16 AM
Last modification on : Monday, September 2, 2019 - 9:43:00 AM

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M. Courteaud, M. Ritz, B. Robineau, J.L. Join, J. Coudray. New geological and hydrogeological implications of the resistivity distribution inferred from audiomagnetotellurics over La Fournaise young shield volcano (Reunion Island). Journal of Hydrology, Elsevier, 1997, 203 (1-4), pp.93-100. ⟨10.1016/S0022-1694(97)00090-5⟩. ⟨hal-02100580⟩

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