HR: 0800h
AN: C51B-0299    [Abstracts]
TI: Three-dimensional GPR investigation of intraglacial hydrologic structures
AU: * Bradford, J
EM: johnb@cgiss.boisestate.edu
AF: Boise State University CGISS, 1910 University Dr., Boise, ID 83725
AU: Harper, J
EM: joel@mso.umt.edu
AF: University of Montana Dept of Geol, 32 Campus Dr. #1296, Missoula, MT 59812
AU: Hess, S
EM: scotthess@cgiss.boisestate.edu
AF: Boise State University CGISS, 1910 University Dr., Boise, ID 83725
AU: Allen, A
EM: all@cgiss.boisestate.edu
AF: Boise State University CGISS, 1910 University Dr., Boise, ID 83725
AB: In a series of studies focused on investigating storage and routing of water within temperate glaciers we have conducted research over five field seasons at Bench Glacier, Chugach Mountains, Alaska.. To date, completed work includes instrumentation over 50 boreholes drilled to the bed of the glacier, logging of the boreholes with down-hole video imaging, and a variety of radar surveys. Each of these components of data collection suggests that internal void spaces are widespread and interconnected over a length scale of at least 10s of meters. The voids are not isolated spherical pockets, but rather planar openings. They are most likely the result of crevassing, but at this point we term them planar voids (cf., fractures, crevasses) to avoid an implication of process. Since the voids are apparently sometimes connected to the bed and each other, it is possible that they provide an additional dimension to the subglacial hydrological system - a place to store and route water. Hence, englacial voids may be an important component of the glacier drainage system and the linkage between hydrology and sliding dynamics. Here we discuss acquisition and analysis of a 50 MHz, three-dimensional ground-penetrating radar survey designed to investigate the 3D distribution and connectivity of the englacial void system. The survey covered a 100 x 100 m area. It was necessary to acquire the data with dense surficial coverage ( 2 m x 1 m grid spacing) in the both the in-line and cross-line directions to correctly image the void system which produced strong 3D dimensional scattering of the radar wavefield. The GPR data volume is supplemented with detailed video log and hydrologic measurements in 16 boreholes that were located within the survey grid.
DE: 0720 Glaciers
DE: 0736 Snow (1827, 1863)
DE: 0999 General or miscellaneous
DE: 1835 Hydrogeophysics
SC: Cryosphere [C]
MN: Fall Meeting 2005