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Seismic velocity models for the Denali fault zone along the Richardson Highway, Alaska

Thomas M. Brocher, Gary S. Fuis, William J. Lutter, Nikolas I. Christensen and Natalia A. Ratchkovski
Seismic velocity models for the Denali fault zone along the Richardson Highway, Alaska (in The 2002 Denali Fault earthquake sequence, Charlotte Rowe (editor), Douglas Christensen (editor) and Gary Carver (editor))
Bulletin of the Seismological Society of America (December 2004) 94 (6, Part B): 85-106


Crustal-scale seismic-velocity models across the Denali fault zone along the Richardson Highway show a 50-km-thick crust, a near vertical fault trace, and a 5-km-wide damage zone associated with the fault near Trans-Alaska Pipeline Pump Station 10, which provided the closest strong ground motion recordings of the 2002 Denali fault earthquake. We compare models, derived from seismic reflection and refraction surveys acquired in 1986 and 1987, to laboratory measurements of seismic velocities for typical metamorphic rocks exposed along the profiles. Our model for the 1986 seismic reflection profile indicates a 5-km-wide low-velocity zone in the upper 1 km of the Denali fault zone, which we interpret as fault gouge. Deeper refractions from our 1987 line image a 40-km wide, 5-km-deep low-velocity zone along the Denali fault and nearby associated fault strands, which we attribute to a composite damage zone along several strands of the Denali fault zone and to the obliquity of the seismic line to the fault zone. Our velocity model and other geophysical data indicate a nearly vertical Denali fault zone to a depth of 30 km. Aftershocks of the 2002 Denali fault earthquake and our velocity model provide evidence for a flower structure along the fault zone consisting of faults dipping toward and truncated by the Denali fault. Wide-angle reflections indicate that the crustal thickness beneath the Denali fault is transitional between the 60-km-thick crust beneath the Alaska Range to the south, and the extended, 30-km-thick crust of the Yukon-Tanana terrane to the north.

ISSN: 0037-1106
EISSN: 1943-3573
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 94
Serial Issue: 6, Part B
Title: Seismic velocity models for the Denali fault zone along the Richardson Highway, Alaska
Title: The 2002 Denali Fault earthquake sequence
Author(s): Brocher, Thomas M.Fuis, Gary S.Lutter, William J.Christensen, Nikolas I.Ratchkovski, Natalia A.
Author(s): Rowe, Charlotteeditor
Author(s): Christensen, Douglaseditor
Author(s): Carver, Garyeditor
Affiliation: U. S. Geological Survey, Menlo Park, CA, United States
Affiliation: Los Alamos National Laboratory, Los Alamos, NM, United States
Pages: 85-106
Published: 200412
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 57
Accession Number: 2005-040984
Categories: SeismologyApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., 8 tables, geol. sketch maps
N63°10'00" - N63°49'60", W146°10'00" - W145°30'00"
Secondary Affiliation: University of Alaska, USA, United StatesCarver Geologic, Kodiak, AK, USA, United StatesUniversity of Wisconsin, USA, United StatesUniversity of Alaska, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200525
Program Name: USGSOPNon-USGS publications with USGS authors
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