HR: 0800h
AN: S51A-0141    [Abstracts]
TI: Stress Field Along the Central Denali Fault, Alaska, From Relocated Aftershocks of the 2002 Earthquake Sequence
AU: * Walter, J
EM: jacob.walter@colorado.edu
AF: University of Colorado at Boulder, Department of Geological Sciences, 2200 Colorado Avenue, Boulder, CO 80309-0399
AU: Ratchkovski, N
EM: natasha@giseis.alaska.edu
AF: Alaska Earthquake Information Center, Geophysical Institute, University of Alaska Fairbanks, 930 Koyukuk Drive, Fairbanks, AK 99775
AB: The Mw 7.9 November 2002 Denali Fault Event was one of the largest intra-continental earthquakes in recent recorded history. More importantly, no such major strike-slip earthquake has been as well-recorded by modern seismic instruments. Augmented by data from temporary stations, we located aftershocks of this event with a high accuracy. By reviewing waveforms and revising previous arrival picks and then applying a double-difference relocation algorithm (Waldhauser and Ellsworth, 2000), we have created the most up-to-date catalog of aftershock locations for the larger aftershocks (M $>$ 3.4). By calculating focal mechanisms, we have shown characteristics of faulting along the ruptured faults. We have identified subsidiary faults just east of the Richardson highway, both north and south of the Denali Fault striking in a similar orientation as the Fault, that exhibit reverse faulting. By implementing the program ZMAP (Wiemer, 2001) we mapped the stress directions across the extent of the rupture. While predominantly a strike-slip rupture, the stress mapping shows some regions of reverse faulting interchanged with regions of strike-slip motion. Furthermore, the orientations of the stress fields exhibit no change across the fault. Where the Talkeetna, Hines Creek, and Denali Faults converge, the largest notable variance in the stress directions occur due to complex interactions with the Hines Creek and Talkeetna Faults as the Denali Fault ruptured.
DE: 1734 Seismology
SC: Seismology [S]
MN: 2004 AGU Fall Meeting