HR: 1400h
AN: G33A-03    [Abstracts]
TI: Definition and Kinematics of the Nicaraguan Forearc and Stable Caribbean From GPS Geodesy
AU: * Styron, R H
EM: rstyron@uark.edu
AF: Department of Geosciences, University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701, United States
AU: Turner, H L
EM: hturner@uark.edu
AF: Department of Geosciences, University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701, United States
AU: James, S A
EM: sjames@uark.edu
AF: Department of Geosciences, University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701, United States
AU: Mattioli, G S
EM: mattioli@uark.edu
AF: Department of Geosciences, University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701, United States
AU: Jansma, P E
EM: pjansma@uark.edu
AF: Department of Geosciences, University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701, United States
AB: The Central American republic of Nicaragua's western margin is characterized by oblique subduction of the Cocos Plate, producing a volcanic arc in the overlying Caribbean Plate (DeMets, 2001). The arc sits in a structural depression with active faulting and related seismicity. Additionally, shear caused by oblique subduction requires accommodation in the forearc via elastic deformation or translation of a rigid forearc sliver. Recently reported GPS geodetic observations indicate nearly rigid forearc translation of ~15 mm yr ^-1 northwestward along the coast (relative to the stable Caribbean geodetic reference frame), with a small trenchward velocity component seen in the coastal sites (Turner et al., 2007). Here we report additional campaign GPS observations whose primary goal is to determine the nature of the boundary between the actively deforming forearc and the stable Caribbean plate to the east. To achieve this and to constrain rates of crustal deformation along this western boundary of the forearc, we have recently installed and occupied an arc- normal transect of 8 geodetic sites from the coast, through the Nicaraguan Depression, and into the stable Caribbean Interior Highlands (completed in early 2007). Along the transect, the new and existing sites are spaced 10- 15 km apart; some of these sites were initially installed in 2000 as part of our regional network. This transect is augmented by a less dense but more broad network of sites throughout western Nicaragua to observe changes in deformational style along strike.
DE: 1209 Tectonic deformation (6924)
SC: Geodesy [G]
MN: 2007 Joint Assembly