HR: 1340h
AN: H23A-1122    [Abstracts]
TI: Hydrogeophysical characterization of bedrock fracture orientations using azimuthal seismic refraction tomography
AU: * Sturtevant, K A
EM: ks58@buffalo.edu
AF: University at Buffalo, 876 Natural Sciences Complex, Buffalo, NY 14260
AU: Baker, G S
EM: gbaker@geology.buffalo.edu
AF: University at Buffalo, 876 Natural Sciences Complex, Buffalo, NY 14260
AU: Snyder, C
EM: csnyder@opaliaenv.com
AF: Opalia Environmental , 25 Monroe Place #11F, Brooklyn, NY 11201
AU: Kopczynski, S
EM: sarahk@crrel.usace.army.mil
AF: CRREL, 72 Lyme Road, Hanover, NH 03755
AB: Seismic anisotropy is a commonly analyzed attribute, mainly in oil exploration and crustal studies. Anisotropy interpretations can also be useful, however, in near-surface applications (upper 200 m) to aid in defining field-scale hydrologic parameters such as bedrock fracture orientation due to the link between seismic anisotropy and fracture anisotropy. A series of seismic refraction tomography profiles were collected in July of 2002 and August of 2003 at Birch Hill on Fort Wainwright in Fairbanks, Alaska, as part of a larger environmental site characterization study to better define the geologic setting and identify structures that may influence groundwater flow and contaminant migration. These data are also used in an effort to explore the usefulness of seismic anisotropy analysis as a tool in hydrogeophysical applications. The intersections of these profiles were analyzed using two different plots (polar and Cartesian) of velocity versus the azimuth of profile orientation. When identifying seismic anisotropy (if it exists) at a particular intersection, the velocities at multiple depths in the subsurface are compared among the intersecting profiles to determine if a particular azimuth indicates higher velocities. Site-wide seismic anisotropy trends were determined by comparing all the results from multiple intersections of over 30 profiles. Interpretable results were obtained from this study. Through the analysis of the intersections, tentative fracture anisotropy trends at the Birch Hill site were obtained. Correlations exist between the known fracture orientations and the anisotropy data.
UR: http://www.geophysics.buffalo.edu
DE: 1832 Groundwater transport
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting