Temporal Variations of Near-surface Seismic Data at the Ploemeur (France) Hydrogeological Observatory - INSU - Institut national des sciences de l'Univers Accéder directement au contenu
Communication Dans Un Congrès Année : 2016

Temporal Variations of Near-surface Seismic Data at the Ploemeur (France) Hydrogeological Observatory

M. Dangeard
  • Fonction : Auteur
R Guérin
Laurent Longuevergne
Julien Thiesson

Résumé

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.
Fichier non déposé

Dates et versions

insu-01360089 , version 1 (05-09-2016)

Identifiants

Citer

M. Dangeard, Sylvain Pasquet, L. Bodet, R Guérin, Laurent Longuevergne, et al.. Temporal Variations of Near-surface Seismic Data at the Ploemeur (France) Hydrogeological Observatory. Near Surface Geoscience 2016 - 22nd European Meeting of Environmental and Engineering Geophysics , Sep 2016, Barcelone, Spain. ⟨10.3997/2214-4609.201602076⟩. ⟨insu-01360089⟩
119 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More