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TitleThere is no pure P- or S-wave land seismic source
AuthorPugin, A; Yilmaz, O
SourceSociety of Exploration Geophysicists, Annual International Meeting, Abstracts p. 5162-5166, https://doi.org/10.1190/segam2017-17650931.1
Alt SeriesNatural Resources Canada, Contribution Series 20170376
PublisherSociety of Exploration Geophysicists
MeetingSociety of Exploration Geophysicists 87th Annual Meeting; Houston; US; September 24-29, 2017
Documentbook
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceOntario
NTS31G/05
AreaOttawa
Subjectstectonics; seismic interpretations; seismic data; seismic surveys; seismicity; geophone arrays; seismic reflection surveys; s waves; p waves; seismic waves
Illustrationsdigrams; seismic profiles
ProgramAquifer Assessment & support to mapping, Groundwater Geoscience
AbstractWe conducted a field experiment at a soil site near Ottawa and recorded 9-C seismic data using a hand-held hammer and a receiver cable with 48 3-C 28-Hz geophones at 0.75-m intervals. The receiver spread length is 35.75 m and the near-offset is 0.75 m. We recorded three triplets of shot records with the impact source in vertical, inline horizontal, and crossline horizontal orientations. We identified several wave modes in the nine field records --- PP, PS, SP, and SS reflections, in addition to refracted waves. We then performed vertical sum of the three records associated with each of the three different source orientations (vertical, inline horizontal, and crossline horizontal) but with common geophone orientation, and computed the semblance spectra of the composite records. We ascertained the wave modes based on the semblance peaks.
This field test led to several important observations regarding characteristics of wave propagation in the nearsurface. First and foremost, based on our experience in using impulsive and vibroseis sources, there is no pure P- or S-wave land seismic source --- any source type can generate any combination of wave modes. Second, a wave mode may not be present in a record acquired with a given source-receiver orientation which theoretically should give rise to that mode, but can appear unexpectedly in a record acquired with a given source-receiver orientation which theoretically should not give rise to that mode. Third, the combination of wave modes captured by a specific sourcereceiver orientation depends on the Vp/Vs ratio. Finally, these observations led to a realization that for a complete
representation of the wavefield propagating within the nearsurface, we need to record multicomponent data.
Summary(Plain Language Summary, not published)
This abstract is delivering about new seismic methods that have the potential to increase the quality of the geophysical imaging of the earth with possible future improved application in environmental and energy sector studies
GEOSCAN ID306975