GEOSCAN, résultats de la recherche


TitreNear surface S-wave seismic reflection profiling - new approaches and insights
AuteurPugin, A J -M; Brewer, K; Cartwright, T; Pullan, S E; Perret, D; Crow, H; Hunter, J A
SourceFirst Break vol. 31, 2013 p. 49-60,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20120226
ÉditeurEAGE Publications
Documentpublication en série
Mediapapier; en ligne; numérique
Sujetsprofils sismiques; levés de reflexion sismiques; méthodes sismiques; ondes transversales; ondes sismiques; géophysique
Illustrationslocation maps; profiles; photographs; plots
ProgrammeAquifer Assessment & support to mapping, Géoscience des eaux souterraines
Résumé(disponible en anglais seulement)
Multi-component high resolution seismic reflection profiling has been extensively tested over a wide variety of ground surfaces across the southern provinces of Canada, showing new potential for applications of the method in groundwater and natural hazards research. The near-surface shear-wave reflection method using vibratory sources and short spacing land streamers equipped with three-component receivers is an excellent tool for accurately characterizing shear-wave velocities and recording optimal, non-aliased shear-wave data in the most polarized direction. A small portable multi-component vibrator developed at the Geological Survey of Canada (GSC) named 'Microvibe' provides higher frequency S-wave and P-wave signals than can be acquired with a Minivib I. In this paper we show that the shear-wave polarization can vary with depth and it may be necessary to combine multiple components together to achieve an optimized stacked section. Significant velocity anisotropies of up to 15% have been observed between the horizontal and vertical directions when using this multi-component Microvibe source. We make key recommendations based on time and space sampling recording windows for successful near surface PP-wave, PS-wave and SS-wave seismic reflection surveys. Using field examples and velocity measurements, we show the complexity of velocities in non-homogeneous media in the near surface.