HR: 0800h
AN: G21C-0656    [Abstracts]
TI: Dislocation Modeling and Comparison With GPS Data to Assess Possible Elastic Strain Accumulation in the Central Lesser Antilles: New Constraints From the NSF REU Site in Dominica Between 2001 and 2007
AU: * Staisch, L
EM: staischl@carleton.edu
AF: Dept. of Geology, Carleton College, One North College, Northfield, MN 55057, United States
AU: Styron, R H
EM: rstyron@uark.edu
AF: Dept. of Geosciences, University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701, United States
AU: James, S
EM: sjames@uark.edu
AF: Dept. of Geosciences, University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701, United States
AU: Turner, H L
EM: hturner@uark.edu
AF: Dept. of Geosciences, University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701, United States
AU: Ashlock, A
EM: andrew.ashlock@gmail.com
AF: Dept. of Geosciences, University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701, United States
AU: Cavness, C L
EM: ccavness@middlebury.edu
AF: Dept. of Geology, Middlebury College, Bicentennial Hall, Middlebury, VT 05753, United States
AU: Collier, X
EM: collier12@yahoo.com
AF: Dept. of Agriculture, University of Arkansas Pine Bluff, 1200 N. University Drive`, Pine Bluff, AR 71601, United States
AU: Fauria, K
EM: kfauria@uoregon.edu
AF: Dept. of Geological Sciences, University of Oregon, 1272 University of Oregon, Eugene, OR 97403, United States
AU: Feinstein, R
EM: rfeinst@uark.edu
AF: Dept. of Geosciences, University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701, United States
AU: Murphy, R
EM: rmurphy5@nd.edu
AF: Dept. of Civil Engineering and Geological Sciences, University of Notre Dame, 156 Fitzpatrick Hall, Notre Dame, IN 46556, United States
AU: Williams, B
EM: nikki50seminole@yahoo.com
AF: Dept. of Agriculture, University of Arkansas Pine Bluff, 1200 N. University Drive`, Pine Bluff, AR 71601, United States
AU: Mattioli, G S
EM: mattioli@uark.edu
AF: Dept. of Geosciences, University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701, United States
AU: Jansma, P E
EM: pjansma@uark.edu
AF: Dept. of Geosciences, University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701, United States
AU: Cothren, J
EM: jcothre@uark.edu
AF: Dept. of Geosciences, University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701, United States
AB: The Caribbean, North and South American plates are converging at a rate of 2 cm/yr in the central region of the Lesser Antilles arc. Here we report high-precision GPS data in concert with forward modeling of a simplified subduction zone geometry to assess strain accumulation for the Lesser Antilles trench. We are able to constrain both vertical and horizontal surface deformation from campaign and continuous GPS observations from 28 geodetic benchmarks located in Guadeloupe, Dominica and Aves Island. Precise station positions were estimated with GIPSY-OASIS II using an absolute point positioning strategy and final, precise orbits, clocks, earth orientation parameters, and x-files. All position estimates were updated to ITRF05 and a revised Caribbean Euler pole was used to place our observations in a CAR-fixed frame. Surface displacements for each site were estimated over 2-7 years. CAR-fixed velocities are projected onto a 500 kilometer transect from the LA trench to Aves Island and compared to calculated displacements for 88 different subduction models. Finite dislocations within an elastic half-space with variable parameters such as angle of the subducting slab, the downdip extent of the locked zone, and percentage of plate interface locking were investigated. Other parameters, such as trench length and slip remained constant. Using a chi-squared, best-fit statistical criterion, the GPS data constrain the subduction interface to a 75 kilometer downdip extent, a 10° dip angle, and near 50% locking. This implies that the subduction zone offshore Dominica is in an interseismic state, thus accumulating strain and causing small westward and upward displacement of the Lesser Antilles relative to the stable Caribbean interior.
DE: 1209 Tectonic deformation (6924)
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
SC: Geodesy [G]
MN: 2007 Fall Meeting