Ice cap melting and low-viscosity crustal root explain the narrow geodetic uplift of the Western Alps

• Published in: Geophysical Research Letters
• Main Authors: Chery, Jean, Genti, Manon, Vernant, Philippe
• Other Authors: Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: western Alps; [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]; Ice cap
• Online Access: https://hal.archives-ouvertes.fr/hal-01332757; https://hal.archives-ouvertes.fr/hal-01332757/document; https://hal.archives-ouvertes.fr/hal-01332757/file/2016GL067821.pdf; https://doi.org/10.1002/2016GL067821

International audience More than 10 years of geodetic measurements demonstrate an uplift rate of 1–3 mm/yr of the high topography region of the Western Alps. By contrast, no significant horizontal motion has been detected. Two uplift mechanisms have been proposed: (1) the isostatic response to denudation responsible for only a fraction of the observed uplift and (2) the rebound induced by the Wurmian ice cap melting which predicts a broader uplifting region than the one evidenced by geodetic observations. Using a numerical model to fit the geodetic data, we show that a crustal viscosity contrast between the foreland and the central part of the Alps, the latter being weaker with a viscosity of 1021 Pa s, is needed. The vertical rates are enhanced if the strong uppermost mantle beneath the Moho is interrupted across the Alps, therefore allowing a weak vertical rheological anomaly over the entire lithosphere.