Skip to content

Highlighting inner structures of Piton de la Fournaise by comparative analysis of unique 3D magnetic and electrical resistivity models

Romain Guillard1 , Lydie Gailler1, Solène Buvat1, Philippe Labazuy1, Erwan Thébault1, Edouard Régis2 and the ANR Scan4Volc team

  • Affiliations: 1 CNRS, IRD, OPGC, Laboratoire Magmas et Volcans, Université Clermont Auvergne, F-63000 Clermont-Ferrand, France; 2 OPGC, Observatoire de Physique du Globe de Clermont, Université Clermont Auvergne, F-63000 Clermont-Ferrand, France 

  • Presentation type: Poster

  • Presentation time: Monday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 126

  • Programme No: 3.1.18

  • Theme 3 > Session 1

Abstract

Imaging inner structure of a volcanic edifice is a fundamental challenge to better understand, constrain and predict its dynamics in order to answer scientific and societal issues. Piton de la Fournaise, a highly active and well-monitored basaltic shield volcano, is an ideal site for geophysical imaging. Such approaches provide essential information to constrain the geometry and spatio-temporal evolution of its active structures at different depths. Firstly, we applied an innovative data processing approach based on a rectangular harmonic analysis to 1) compile a large magnetic dataset acquired at different spatial (ground, UAV and helicopter-borne measurements) and temporal scales (from 2014 to 2024), and 2) provide a spatially consistent dataset for 3D high resolution numerical inversion of the Terminal Cone. Secondly, we carried out a high-resolution 3D electrical resistivity tomography of the same area using an innovative approach (FullWaver method). It presents the advantage of decoupling the electrical current injection and reception systems, enabling us to cover a large area with a complex topography down to a depth of about 1 km below the summit. A detailed comparative analysis of the 3D models provides new information on the nature of the active structures and their extension within the volcanic edifice. This gives us a picture of shallow magmatic and hydrothermal systems, weakness axes and preferential path for fluid circulation at different depths. These observations constitute a new reference of structure of the volcano and will make it possible to study the spatio-temporal evolution (i.e. 4D) of Piton de la Fournaise.