HR: 11:50h
AN: T42A-07    [Abstracts]
TI: Subduction of an Aseismic Ridge: Interseismic Deformation Above the Cocos Ridge, Costa Rica
AU: * LaFemina, P C
EM: plafemina@rsmas.miami.edu
AF: University of Miami - RSMAS, Division of Marine Geology and Geophysics, 4600 Rickenbacker Cswy, Miami, FL 33149 United States
AU: Dixon, T H
EM: tdixon@rsmas.miami.edu
AF: University of Miami - RSMAS, Division of Marine Geology and Geophysics, 4600 Rickenbacker Cswy, Miami, FL 33149 United States
AU: Scwartz, S
EM: sschwartz@emerald.ucsc.edu
AF: University of California - Santa Cruz, Earth Sciences 1156 High St, Santa Cruz, CA 95064 United States
AU: Protti, M
EM: jprotti@una.ac.cr
AF: OVSICORI, Universidad Nacional Apartado 2346-3000, Heredia, 3000 Costa Rica
AU: Gonzalez, V
EM: vgonzale@una.ac.cr
AF: OVSICORI, Universidad Nacional Apartado 2346-3000, Heredia, 3000 Costa Rica
AB: Subduction of aseismic ridges, seamounts and thickened, buoyant oceanic crust often results in deformation of the overriding plate. The Cocos Ridge and sub parallel seamount chains have been subducting along the Middle America Trench (MAT) for >0.5 Ma, resulting in cessation of volcanism, uplift of the Talamanca Range, deformation of the outer fore arc and shortening in the fore arc and back arc of southern Costa Rica and northern Panama. Large magnitude earthquakes (Mw >7.0) have occurred along the Osa segment of the MAT in 1983, 1941 and 1904 and along the north Panama deformed belt in 1916 and 1991. Previous studies demonstrated that orthogonal Cocos Plate-Panama block convergence is partitioned between ~8 cm/yr on the subduction interface and on out-of-sequence thrust faults in the fore arc and ~1 cm/yr along the northern Panama deformed belt. Additionally, it has been suggested that the subduction zone interface is fully locked from 10-50 km depth during the interseismic period (Norabuena et al., 2004). We reevaluate the pattern of strain accumulation across the Osa Peninsula and Fila Costena, located directly above the axis of the aseismic Cocos Ridge, integrating up to ten years of campaign GPS data, including new sites, and new geologic estimates of shortening. Additionally, we investigate the broader tectonic effects of aseismic ridge and seamount subduction on the arc and fore arc of Costa Rica.
DE: 1209 Tectonic deformation (6924)
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
DE: 3060 Subduction zone processes (1031, 3613, 8170, 8413)
DE: 8104 Continental margins: convergent
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: Fall Meeting 2005