Dernière mise à jour le : 4 septembre 2016

Etude de la zone critique : variations temporelles des données sismiques

DESCRIPTION

Near-surface seismic methods are mainly used to determine the geometrical characteristics of hydrosystems (and to provide elements that are interesting for hydrogeologists such as separating aquifer layers, setting up systems boundaries, highlighting fractures etc.). Recent methodological advances suggest the high potential of seismic methods to investigate the mechanical properties of the Critical Zone (CZ), by exploiting the full wealth of seismic records. Indeed, the behavior of Shear (S) and Pressure (P) waves in the presence of water is partially decoupled, so that the ratio of their propagation velocities VP/VS is strongly linked to water saturation. We propose here a time-lapse application of this approach. Two seismic acquisitions were carried out under distinct hydrogeological conditions along the same line at the Ploemeur hydrogeological observatory (South Brittany, France). Vertical component seismic data were recorded to extract: (i) P-wave first arrival times and (ii) Rayleigh-wave phase velocities. The significant variations with time and space, of both datasets, indicate marked changes in mechanical properties of the CZ that have to be compared to soil moisture variations in the unsaturated zone and groundwater level variations.

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keyboard_arrow_right Titre : Etude de la zone critique : variations temporelles des données sismiques
keyboard_arrow_right Type de documentation : Articles
keyboard_arrow_right Auteur(s) personne(s) : Thiesson Julien, Longuevergne Laurent, Guérin R, Bodet L., Pasquet Sylvain, Dangeard M.
keyboard_arrow_right Date de publication : 4 septembre 2016
keyboard_arrow_right Tags thématiques : séisme, hydrogéologie
keyboard_arrow_right Localisation : PLOEMEUR
keyboard_arrow_right Langue : Français

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