Paper No. 144-0
NEAR-SURFACE SH-WAVE REFRACTION AND REFLECTION AND THEIR APPLICATIONS IN OREGON
WANG, Zhenming, Kentucky Geological Survey, Univ of Kentucky, 228 Mining and Mineral Resources Building, Lexington, KY 40506-0107, zwang@kgs.mm.uky.edu, WOOLERY, Edward W., Department of Geological Sciences/Kentucky Geological Survey, Univ of Kentucky, 228 Mining and Mineral Resources Building, Lexington, KY 40506-0107, and MADIN, Ian P., Oregon Department of Geology and Mineral Industries, 800 NE Oregon Street #28, Suite 965, Portland, OR 97232

Thick, unconsolidated soils with high ground-water levels are present in most of western Oregon. These conditions often result in a lack of P-wave impedance contrasts necessary for reflection/refraction signal generation, thereby making the conventional energy source ineffectual for defining the near-surface soil properties. Shear waves, however, propagate only in the soil matrix and are not influenced by pore fluids. This makes shear-wave refraction/reflection more effective for characterizing near-surface soil properties and subsurface geometry. The SH-wave is a shear wave with a particle motion parallel to the ground surface, and is easily generated with hammers or other sources. SH-wave refraction and reflection techniques have been used to characterize near-surface site conditions and neotectonic features in western Oregon. The case histories include shear- wave velocity measurements of the top 30 meters of soils in communities throughout western Oregon, as well as fault characterizations in the Willamette Valley. These case histories show that SH-wave refraction and reflection methods are very effective for characterizing near-surface soil conditions.

GSA Annual Meeting, November 5-8, 2001
General Information for this Meeting
Session No. 144
Contributions of High-Resolution Geophysics to Understanding Neotectonics and Seismic Hazard
Hynes Convention Center: 210
1:30 PM-5:30 PM, Wednesday, November 7, 2001
 

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