HR: 09:30h
AN: S11B-05 INVITED     [PDF]
TI: The Denali Fault: Crustal deformation before and after the 2002, Mw=7.9, Denali Fault Earthquake
AU: * Freymueller, J T
EM: jeff@giseis.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: Fletcher, H
EM: hilary@giseis.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: Hreinsd\'{o}ttir, S
EM: sigrun@giseis.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: Larsen, C F
EM: chris@giseis.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: B\"urgmann, R
EM: burgmann@seismo.berkeley.edu
AF: University of California, Berkeley, Department of Earth and Planetary Science, Berkeley, CA 94720 United States
AU: Calais, E
EM: ecalais@purdue.edu
AF: Purdue University, Department of Earth and Atmospheric Sciences, West Lafayette, IN 47907 United States
AU: Freed, A
EM: freed@purdue.edu
AF: Purdue University, Department of Earth and Atmospheric Sciences, West Lafayette, IN 47907 United States
AB: The Mw 7.9 November 3, 2002 Denali fault earthquake ranks among the largest continental strike slip earthquakes in the last few decades, and is perhaps the best-recorded earthquake of its size from a geodetic point of view. EDM surveys across the Denali fault were carried out by the USGS in the 1980s, which showed low shear strain rates across the fault. We have carried out GPS measurements on two transects across the Denali fault since 1997. These data show 6-8 mm/yr of right-lateral strike slip motion across the Alaska Range. We explain these data using a model in which one or two faults of the Denali fault system slip with a total slip rate of 8 mm/yr. Because the Denali fault forms a small circle about a pole of rotation just offshore of the Kenai Peninsula, we interpret the Denali fault as forming the northern boundary of a block comprising much of southern Alaska that rotates counter-clockwise relative to North America. Following the earthquake, with the technical support of UNAVCO, we have installed 16 continuous GPS sites at a wide range of distances from the rupture, and carried out repeated campaign-style surveys of more than 50 additional sites. Horizontal postseismic displacement rates at continuous sites up to 200 km from the rupture reached 1-2 mm/day in the first month after the event. They gradually decayed to ~0.2 mm/day 8 months after the event at the sites closest to the rupture. Displacement rates measured 8 months after the event were still ~10 times larger than the pre-earthquake secular rates.
DE: 1206 Crustal movements--interplate (8155)
DE: 1208 Crustal movements--intraplate (8110)
DE: 7230 Seismicity and seismotectonics
SC: Seismology [S]
MN: 2003 Fall Meeting