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

Jean Chery (1) , Manon Genti (1) , Philippe Vernant (1)

1 Géosciences Montpellier

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.

Mots clés: western Alps

Domaines: Géophysique [physics.geo-ph]

Jean Chery, Manon Genti, Philippe Vernant. Ice cap melting and low-viscosity crustal root explain the narrow geodetic uplift of the Western Alps. Geophysical Research Letters, 2016, 43 (7), pp.3193-3200. ⟨10.1002/2016GL067821⟩. ⟨hal-01332757⟩