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Bulletin of the Seismological Society of America; December 2004; v. 94; no. 6B; p. S5-S22; DOI: 10.1785/0120040619
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The Susitna Glacier Thrust Fault: Characteristics of Surface Ruptures on the Fault that Initiated the 2002 Denali Fault Earthquake

Anthony J. Crone1, Stephen F. Personius1, Patricia A. Craw2, Peter J. Haeussler3 and Lauren A. Staft2

1 U.S. Geological Survey
MS 966, Box, 25046
Denver, Colorado 80225-0046
 (A.J.C., S.F.P.)

2 Alaska Division of Geological and Geophysical Surveys
3354 College Road
Fairbanks, Alaska 99709
 (P.A.C., L.A.S.)

3 U.S. Geological Survey
4200 University Drive
Anchorage, Alaska 99508
 (P.J.H.)

The 3 November 2002 Mw 7.9 Denali fault earthquake sequence initiated on the newly discovered Susitna Glacier thrust fault and caused 48 km of surface rupture. Rupture of the Susitna Glacier fault generated scarps on ice of the Susitna and West Fork glaciers and on tundra and surficial deposits along the southern front of the central Alaska Range. Based on detailed mapping, 27 topographic profiles, and field observations, we document the characteristics and slip distribution of the 2002 ruptures and describe evidence of pre-2002 ruptures on the fault. The 2002 surface faulting produced structures that range from simple folds on a single trace to complex thrust-fault ruptures and pressure ridges on multiple, sinuous strands. The deformation zone is locally more than 1 km wide. We measured a maximum vertical displacement of 5.4 m on the south-directed main thrust. North-directed backthrusts have more than 4 m of surface offset. We measured a well-constrained near-surface fault dip of about 19° at one site, which is considerably less than seismologically determined values of 35°–48°. Surface-rupture data yield an estimated magnitude of Mw 7.3 for the fault, which is similar to the seismological value of Mw 7.2. Comparison of field and seismological data suggest that the Susitna Glacier fault is part of a large positive flower structure associated with northwest-directed transpressive deformation on the Denali fault. Prehistoric scarps are evidence of previous rupture of the Sustina Glacier fault, but additional work is needed to determine if past failures of the Susitna Glacier fault have consistently induced rupture of the Denali fault.




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P. J. Haeussler, D. P. Schwartz, T. E. Dawson, H. D. Stenner, J. J. Lienkaemper, B. Sherrod, F. R. Cinti, P. Montone, P. A. Craw, A. J. Crone, et al.
Surface Rupture and Slip Distribution of the Denali and Totschunda Faults in the 3 November 2002 M 7.9 Earthquake, Alaska
Bulletin of the Seismological Society of America, December 1, 2004; 94(6B): S23 - S52.
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