HR: 14:40h
AN: NS23A-05    [Abstracts]
TI: Integrated Geophysical and Geological Fault Assessment at a Hazardous-Waste Landfill: Fluorspar Area Fault Complex, Central United States
AU: * Woolery, E
EM: woolery@uky.edu
AF: University of Kentucky, Dept. of Earth & Environmental Sciences 101 Slone Research Building, Lexington, KY 40506-0053, United States
AU: Baldwin, J
EM: baldwin@lettis.com
AF: William Lettis & Associates, 1777 Botelho Dr., Suite 262, Walnut Creek, CA 94506, United States
AU: Kelson, K
EM: kelson@lettis.com
AF: William Lettis & Associates, 1777 Botelho Dr., Suite 262, Walnut Creek, CA 94506, United States
AU: Hampson, S
EM: skhampson@alltel.com
AF: University of Kentucky, Kentucky Consortium for Energy and Environment 233 Mining & Minerals Building, Lexington, KY 40506, United States
AU: Givler, R
EM: givler@lettis.com
AF: William Lettis & Associates, 1777 Botelho Dr., Suite 262, Walnut Creek, CA 94506, United States
AB: Federal and Commonwealth of Kentucky regulations require proposed hazardous waste facilities undergo a surface-fault rupture hazard assessment prior to issuing construction permits. Permanent ground deformation may expose below-ground structures such as landfills and settling ponds, as well as above-ground structures such as tanks and incinerators to rupture and/or topple failure, and thus potential uncontrolled contaminant release. Regulations prohibit placing new hazardous waste facilities within 61 m (200 ft) of a Holocene-active fault. However, identifying and characterizing active faults in areas lacking geomorphic expression is a challenging task, as exemplified in and near the New Madrid seismic zone and Fluorspar Area fault complex (FAFC). In the mid-continent, surface manifestations of active faults are generally impeded by thick sequence of relatively weak, water-saturated Mississippi embayment sediment overlying bedrock. The soft sediment overburden and long recurrence interval between large earthquakes conceal neotectonic structures in bedrock and commonly fail to produce significant or noticeable geomorphic features. A proposed hazardous-waste landfill in western Kentucky is located within the upper Mississippi embayment and above the late Proterozoic-early Cambrian FAFC, an area also coincident with diffuse microseismicity. Integrated geophysical and geological methodologies were essential for a surface-fault rupture assessment. Nearly 1 km of SH-wave seismic reflection data were collected and interpreted for evidence of late Quaternary deformation. Five significant high-angle anomalies were interpreted to extend within approximately 7 m of the ground surface, near the upper limit of the seismic sampling. Eighty-six, densely spaced, continuous cores, each 9.1 m deep, intersected these features. Stratigraphic and chronological analyses were performed on the cores to assess the presence or absence of structure, and to determine the near-surface extent and age of the features. The upper 10 m of sediment ranged between nearly16 ka and greater than 125 ka. Interpretations of geologic cross sections indicate that the most abrupt elevation changes were constrained to post-date a 53.6 to 75.5 ka loess deposit; however, no perceptible displacement was found at the base of a younger loess dated between 16.6 and 23.5 ka. Collectively, these analyses indicate an absence of Holocene deformation beneath the proposed landfill site.
DE: 0900 EXPLORATION GEOPHYSICS
DE: 0935 Seismic methods (3025, 7294)
DE: 7221 Paleoseismology (8036)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Near-Surface Geophysics [NS]
MN: 2007 Fall Meeting