HR: 1330h
AN: S12A-0365    [PDF]
TI: The 3 November 2002 M7.9 Denali Fault, Alaska Earthquake: Double Difference Relocation of Aftershocks.
AU: * Williams, T W
EM: travis@giseis.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, P.O. Box 757320, Fairbanks, AK 99775-7320 United States
AU: Ratchkovski, N
EM: natasha@giseis.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, P.O. Box 757320, Fairbanks, AK 99775-7320 United States
AU: Hansen, R A
EM: roger @giseis.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, P.O. Box 757320, Fairbanks, AK 99775-7320 United States
AB: The M7.9 Denali Fault earthquake occurred at approximately 1:12 PM AST on 3 November 2002, rupturing nearly 300 km of the Denali fault, a major right lateral strike-slip feature in central Alaska. This event is the largest earthquake recorded on the Denali fault system. The Denali Fault earthquake was preceded by the 23 October 2002 M6.7 Nenana Mountain earthquake that ruptured a segment of the Denali fault about 20 km to the west of the M7.9 epicenter. Following the Nenana Mountain event, the Alaska Earthquake Information Center (AEIC) began the deployment of a temporary network of broadband and strong motion seismometers to supplement the 350 existing stations of the Alaska Seismic Network in recording aftershocks. This network was distributed along the Alaska, Glenn, Richardson and Denali highways and several instruments along the Nebesna Road. Six of these instruments were installed prior to the M7.9 event and 20 more in the week following. In the first month following the Denali Fault earthquake over 8 000 aftershocks were recorded. Here we present the double difference relocation results for aftershocks of the Nenana Mountain and Denali Fault events. The distribution of aftershocks indicated complex faulting along the rupture zone. Near the M7.9 epicenter, the aftershock distribution is bounded to the south by the Susitna Glacier fault but is not constrained by the Denali fault to the north. Many of the aftershocks north of the M7.9 epicenter have thrust mechanisms which may indicate that a series of small thrusts was activated by the earthquake north of the Denali fault. Additionally, heightened seismicity is observed on many smaller faults adjoining the Denali fault following the M7.9 event. From these observations, it is evident that the Denali Fault earthquake activated a significant portion of the Denali fault system in Central Alaska.
DE: 7230 Seismicity and seismotectonics
SC: Seismology [S]
MN: 2003 Fall Meeting