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U.S. Geological Survey, Seattle, WA
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- PublicationRestrictedSurface Rupture and Slip Distribution of the Denali and Totschunda Faults(2004-12)
; ; ; ; ; ; ; ; ; ; ; ;Haeussler, P. J.; U.S. Geological Survey ;Schwartz, D. P.; U.S. Geological Survey ;Dawson, T. E.; U.S. Geological Survey ;Stenner, H. D.; U.S. Geological Survey ;Lienkaemper, J. J.; U.S. Geological Survey ;Sherrod, B.; U.S. Geological Survey ;Cinti, F. R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Montone, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Craw, P. A.; U.S. Geological Survey ;Crone, A. J.; State of Alaska, Department of Natural Resources, Fairbanks, Alaska ;Personius, S. F.; U.S. Geological Survey; ; ; ; ; ; ; ; ; ; The 3 November 2002 Denali fault, Alaska, earthquake resulted in 341 km of surface rupture on the Susitna Glacier, Denali, and Totschunda faults. The rupture proceeded from west to east and began with a 48-km-long break on the previously unknown Susitna Glacier thrust fault. Slip on this thrust averaged about 4 m (Crone et al., 2004). Next came the principal surface break, along 226 km of the Denali fault, with average right-lateral offsets of 4.5–5.1 m and a maximum offset of 8.8 m near its eastern end. The Denali fault trace is commonly left stepping and north side up. About 99 km of the fault ruptured through glacier ice, where the trace orientation was commonly influenced by local ice fabric. Finally, slip transferred southeastward onto the Totschunda fault and continued for another 66 km where dextral offsets average 1.6–1.8 m. The transition from the Denali fault to the Totschunda fault occurs over a complex 25-km-long transfer zone of right-slip and normal fault traces. Three methods of calculating average surface slip all yield a moment magnitude of Mw 7.8, in very good agreement with the seismologically determined magnitude of M 7.9. A comparison of strong-motion inversions for moment release with our slip distribution shows they have a similar pattern. The locations of the two largest pulses of moment release correlate with the locations of increasing steps in the average values of observed slip. This suggests that slipdistribution data can be used to infer moment release along other active fault traces.141 26 - PublicationOpen AccessSurface Rupture of the November 2002 M7.9 Denali Fault Earthquake, Alaska, and Comparison to Other Strike-Slip Ruptures(2004-08)
; ; ; ; ; ; ; ; ; ;Haeussler, P. J.; U.S. Geological Survey, Anchorage, AK ;Schwartz, D. P.; U.S. Geological Survey, Menlo Park, CA ;Dawson, T. E.; U.S. Geological Survey, Menlo Park, CA ;Stenner, H. D.; U.S. Geological Survey, Menlo Park, CA ;Lienkaemper, J. J.; U.S. Geological Survey, Menlo Park, CA ;Cinti, F. R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Montone, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Sherrod, B.; U.S. Geological Survey, Seattle, WA ;Craw, P.; Division of Geological and Geophysical Surveys, Fairbanks, AK; ; ; ; ; ; ; ; On November 3, 2002, a moment-magnitude (Mw) 7.9 earthquake produced 340 km of surface rupture on the Denali fault and two related faults in central Alaska. The rupture, which proceeded from west to east, began with a 40-km-long break on a previously unknown thrust fault. Estimates of surface slip on this thrust were 3-6 m. Next came the principal surface break, along 220 km of the Denali fault. There, right-lateral offset averaged almost 5 m and increased eastward to a maximum of nearly 9 m. Finally, slip turned southeastward onto the Totschunda fault, where dextral offsets up to 3 m continued for another 70 km. This three-part rupture ranks among the longest documented strike-slip events of the past two centuries. The surface-slip distribution supports and clarifies models of seismological and geodetic data that indicated initial thrusting followed by rightlateral strike slip, with the largest moment release near the east end of the Denali fault. The Denali fault ruptured beneath the Trans-Alaska oil pipeline. The pipeline withstood almost 6 m of lateral offset, because engineers designed it to survive such offsets based on pre-construction geological studies. The Denali fault earthquake was typical of large-magnitude earthquakes on major intracontinental strike-slip faults, in the length of the rupture, the multiple fault strands that ruptured, and the variable slip along strike.156 559