HR: 1330h
AN: T43B-03    [Abstracts]
TI: GPS Constraints on Lesser Antilles Forearc Motion and Rigid Caribbean Plate
AU: * López, A M
EM: alberto@earth.northwestern.edu
AF: Northwestern University, 1850 Campus Drive Locy Hall, Evanston, IL 60208 United States
AU: Stein, S
EM: seth@earth.northwestern.edu
AF: Northwestern University, 1850 Campus Drive Locy Hall, Evanston, IL 60208 United States
AU: Sella, G
EM: giovanni@earth.northwestern.edu
AF: Northwestern University, 1850 Campus Drive Locy Hall, Evanston, IL 60208 United States
AU: Dixon, T H
EM: tdixon@rsmas.miami.edu
AF: Rosentiel School of Marine and Atmospheric Sciences University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149 United States
AU: Calais, E
EM: ecalais@purdue.edu
AF: Earth & Atmospheric Sciences Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051 United States
AU: Jansma, P E
EM: pjansma@uark.edu
AF: University of Arkansas Department of Geosciences, 113 Ozark Hall, Fayetteville, AR 72701 United States
AB: We are using a decade of Global Positioning System data to address two tectonic problems of the Caribbean (CA) plate; 1) Whether a forearc sliver exists along the Lesser Antilles forearc and if so what is its dynamics and location, and 2) Whether the Caribbean plate is deforming internally. We approach this problem by developing GPS-derived velocity vectors at sites within the CA plate and its boundaries and comparing them to four decades of earthquake data. In a number of subduction zones, misfits between slip vectors and predicted convergence azimuths from Euler vectors suggest the presence of a forearc sliver, where trench-parallel motion is accommodated along a strike-slip fault system. Such a situation may be occurring at the eastern boundary of the CA plate along the Lesser Antilles (LA) forearc, where the North America (NA) plate subducts obliquely. Comparing slip vectors of shallow (0-60 km) thrust events to the predicted motions of GPS-based Euler vectors show a systematic northerly misfit, suggesting a trench-parallel component of motion taken up by the forearc sliver. This possibility can be tested with GPS data from the forearc. In addition, we use new GPS data to constrain the internal rigidity of the plate. Previous GPS work yielded a possible upper bound on internal deformation of 4-6 mm/yr. With an expansion in the data set on critically located stations in the CA plate (SANA, ROJO, CRO1 and AVES), we have computed new sets of Euler vector pairs for the CA-NA and CA-South America plate pairs.
DE: 1206 Crustal movements--interplate (8155)
DE: 1208 Crustal movements--intraplate (8110)
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
DE: 7230 Seismicity and seismotectonics
DE: 8158 Plate motions--present and recent (3040)
SC: Tectonophysics [T]
MN: 2005 Joint Assembly