HR: 0803h
AN: NS11D-0790    [Abstracts]
TI: 3-D Resistivity Tomography for Cliff Stability Study at the D-Day Pointe du Hoc Historic Site in Normandy, France
AU: * Udphuay, S
EM: suwimon@geo.tamu.edu
AF: Dept. of Geology and Geophysics, Texas A&M University, College Station, TX 77843, United States
AU: Everett, M E
EM: everett@geo.tamu.edu
AF: Dept. of Geology and Geophysics, Texas A&M University, College Station, TX 77843, United States
AU: Guenther, T
EM: t.guenther@gga-hannover.de
AF: Institut für Geowissenschaftliche Gemeinschaftsaufgaben, Stilleweg 2, Hannover, 30655, Germany
AU: Warden, R R
EM: r-warden@tamu.edu
AF: Dept. of Architecture, Texas A&M University, College Station, TX 77843, United States
AB: The D-Day invasion site at Pointe du Hoc in Normandy, France is one of the most important World War II battlefields. The site remains today a valuable historic cultural resource. However the site is vulnerable to cliff collapses that could endanger the observation post building and U.S. Ranger memorial located just landward of the sea stack, and an anti-aircraft gun emplacement, Col. Rudder's command post, located on the cliff edge about 200 m east of the observation post. A 3-D resistivity tomography incorporating extreme topography is used in this study to provide a detailed site stability assessment with special attention to these two buildings. Multi-electrode resistivity measurements were made across the cliff face and along the top of the cliff around the two at-risk buildings to map major subsurface fracture zones and void spaces that could indicate possible accumulations and pathways of groundwater. The ingress of acidic groundwater through the underlying carbonate formations enlarges pre-existing tectonic fractures via limestone dissolution and weakens the overall structural integrity of the cliff. The achieved 3-D resistivity tomograms provide diagnostic subsurface resistivity distributions. Resistive zones associated with subsurface void spaces have been located. These void spaces constitute a stability geohazard as they become significant drainage routes during and after periods of heavy rainfalls.
DE: 0925 Magnetic and electrical methods (5109)
DE: 1835 Hydrogeophysics
DE: 4217 Coastal processes
SC: Near-Surface Geophysics [NS]
MN: 2007 Fall Meeting