HR: 09:05h
AN: T51E-05    [Abstracts]
TI: Earthquake Cycle Deformation and Forearc Sliver Translation in the Rupture Zone of the 1960 Chile Earthquake
AU: * Bevis, M
EM: mbevis@osu.edu
AF: Ohio State University, School of Earth Sciences, 125 S Oval Mall, Columbus, OH 43210, United States
AU: Wang, K
EM: KWang@NRCan.gc.ca
AF: Pacific Geoscience Center, 9860 W Saanich Rd, Sidney, BC V8L 4B2, Canada
AU: Hu, Y
EM: yhu@NRCan.gc.ca
AF: University of Victoria, School of Earth and Ocean Sciences, Victoria, BC V8P 5C2, Canada
AU: Kendrick, E
EM: kendrick.42@osu.edu
AF: Ohio State University, School of Earth Sciences, 125 S Oval Mall, Columbus, OH 43210, United States
AU: Smalley, R
EM: rsmalley@memphis.edu
AF: University of Memphis, CERI, 3890 Central Ave, Memphis, TN 38152, United States
AB: We present GPS velocity solutions for the entire latitudinal range of the rupture zone of the great (Mw ~ 9.5) 1960 earthquake. Previous studies presented velocity solutions only for the northern half of this zone. The new measurements indicate that the pattern of opposing, roughly arc-normal, motions previously documented in the north also occur in the south. Interseismic shortening (eastward motion) is dominant near the coast, whereas postseismic transient deformation (westward motion) is dominant near the Chile-Argentina border. The new observations also reveal for the first time than in the southern part of the rupture zone a forearc sliver is travelling northward due to dextral motion across the Liquine-Ofqui fault system. This dextral shearing has a maximum rate of about 6.5 mm/yr near the southern end of the rupture zone, and declines to the north. We also observe a southwards decrease in the margin-normal velocities of the coastal area. We suggest that this decrease reflects a change either in the width or the frictional properties of the megathrust zone. The thermal structure of the megathrust zone varies with distance to the triple junction. We present a fairly simple 3D viscoelasatic finite element model that demonstrates that while our interpretation is not unique, it is broadly consistent with the GPS observations available to date.
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8104 Continental margins: convergent
DE: 8108 Continental tectonics: compressional
SC: Tectonophysics [T]
MN: 2007 Fall Meeting