Tamburello G. auteur aut IRD Moune S. auteur aut IRD Allard P. auteur aut IRD Venugopal S. auteur aut IRD Robert V. auteur aut IRD Rosas-Carbajal M. auteur aut IRD Deroussi S. auteur aut IRD Kitou G. T. auteur aut IRD Didier T. auteur aut IRD Komorowski J. C. auteur aut IRD Beauducel François auteur aut IRD De Chabalier J. B. auteur aut IRD Le Marchand A. auteur aut IRD Le Friant A. auteur aut IRD Bonifacie M. auteur aut IRD Dessert C. auteur aut IRD Moretti R. auteur aut IRD text journalArticle eng text/pdf reformatted digital access Over the past two decades, La Soufriere volcano in Guadeloupe has displayed a growing degassing unrest whose actual source mechanism still remains unclear. Based on new measurements of the chemistry and mass flux of fumarolic gas emissions from the volcano, here we reveal spatio-temporal variations in the degassing features that closely relate to the 3D underground circulation of fumarolic fluids, as imaged by electrical resistivity tomography, and to geodetic-seismic signals recorded over the past two decades. Discrete monthly surveys of gas plumes from the various vents on La Soufriere lava dome, performed with portable MultiGAS analyzers, reveal important differences in the chemical proportions and fluxes of H2O, CO2, H2S, SO2 and H-2,H- which depend on the vent location with respect to the underground circulation of fluids. In particular, the main central vents, though directly connected to the volcano conduit and preferentially surveyed in past decades, display much higher CO2/SO2 and H2S/SO2 ratios than peripheral gas emissions, reflecting greater SO2 scrubbing in the boiling hydrothermal water at 80-100 m depth. Gas fluxes demonstrate an increased bulk degassing of the volcano over the past 10 years, but also a recent spatial shift in fumarolic degassing intensity from the center of the lava dome towards its SE-NE sector and the Breislack fracture. Such a spatial shift is in agreement with both extensometric and seismic evidence of fault widening in this sector due to slow gravitational sliding of the southern dome sector. Our study thus provides an improved framework to monitor and interpret the evolution of gas emissions from La Soufriere in the future and to better forecast hazards from this dangerous andesitic volcano. specialized la soufriere guadeloupe volcanic gas volcanic unrest hydrothermal gas multigas extensometry GUADELOUPE LA SOUFRIERE VOLCAN 066 062 9 11 art. 480 [25 p.] 2019 https://www.documentation.ird.fr/hor/fdi:010077458 10.3390/geosciences9110480 [F B010077458] https://www.documentation.ird.fr/hor/fdi:010077458 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers20-01/010077458.pdf IRD - Base Horizon / Pleins textes 2020-02-05 2025-02-24 fdi:010077458 fre