Geotechnical Reconnaissance of the 2002 Denali Fault, Alaska Earthquake
Robert Kayen,a) M.EERI, Eric Thompson,a) Diane Minasian,a) Robb E.S. Moss,b) M.EERI, Brian Collins,b) M.EERI, Nicholar Sitar,b) M.EERI, Douglas Dregerb), and Gary Carverc)
a) United States Geological Survey, 345 Middlefield Road, Menlo Park, CA 94043
b) University of California at Berkeley, Berkeley, CA 94720
c) Carver Geologic, Inc., P.O. Box 52, Kodiak, AK 99615
Reprinted From:
Earthquake Spectra, Volume 20, No. 3, pages 639—667, August 2004: © 2004,
Earthquake Engineering Research Institute
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The 2002 M7.9 Denali fault earthquake resulted in 340 km of ruptures along three separate faults, causing widespread liquefaction in the fluvial deposits of the alpine valleys of the Alaska Range and eastern lowlands of the Tanana River. Areas affected by liquefaction are largely confined to Holocene alluvial deposits, man-made embankments, and backfills. Liquefaction damage, sparse surrounding the fault rupture in the western region, was abundant and severe on the eastern rivers: the Robertson, Slana, Tok, Chisana, Nabesna and Tanana Rivers. Synthetic seismograms from a kinematic source model suggest that the eastern region of the rupture zone had elevated strong-motion levels due to rupture directivity, supporting observations of elevated geotechnical damage. We use augered soil samples and shear-wave velocity profiles made with a portable apparatus for the spectral analysis of surface waves (SASW) to characterize soil properties and stiffness at liquefaction sites and three trans-Alaska pipeline pump station accelerometer locations.
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Sand boils in the upper Susitna Valley.
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