HR: 0800h
AN: G21A-0134    [Abstracts]
TI: Tectonic Implications of Recent Campaign GPS Measurements Along the Central Region of the Lesser Antilles arc: Results from Dominica 2001-2004
AU: * Blessing, B C
EM: bcblessi@mtu.edu
AF: Michigan Technological University, 1400 Townsend dr., Houghton, MI 49931 United States
AU: Turner, H L
EM: hturner@uark.edu
AF: University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701 United States
AU: Fitzgibbon, K
EM: kfitzgi@uark.edu
AF: University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701 United States
AU: Davidson, R
EM: rtdypb@umr.edu
AF: University of Missouri-Rolla, 1870 Miners Circle, Rolla, MO 65409 United States
AU: Parra, J
EM: paplotl@hotmail.com
AF: Cal Poly Pomona, 3801 West Temple Avenue, Pomona, CA 91768 United States
AU: Jansma, P E
EM: pjansma@uark.edu
AF: University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701 United States
AU: Mattioli, G S
EM: mattioli@uark.edu
AF: University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701 United States
AB: The volcanic island of Dominica is located in the central region of the Lesser Antilles arc, an obliquely convergent boundary between the Caribbean and North American plates. An initial GPS campaign was conducted in 2001 to expand our regional GPS field for the eastern Caribbean and to provide baseline geodetic data for examining volcanic unrest in Dominica. In 2001, nine sites were established, the majority near the southern volcanic region, where a recent shallow seismic swarm had occurred. A second GPS campaign was conducted in 2003, following another seismic swarm in the north. This campaign re-occupied the original nine sites and established three more. The density of GPS sites on the island was improved and all the existing sites were reoccupied in 2004. Today there are eighteen high precision GPS sites on the island. All GPS observations were made with dual-frequency, code-phase receivers and choke ring antenna. At least 2.5 days of continuous observations were obtained on each site for each epoch in 2001, 2003, and 2004. Daily site positions were calculated with an absolute point positioning strategy using GIPSY-OASIS-II and final precise orbit and clock corrections from JPL. The measured surface deformation field on Dominica potentially contains components of motion from both shallow volcanic sources as well as elastic strain accumulation from the plate interface. Because volcanic deformation may be cyclical and superimposed on the background tectonic deformation field, we have chosen to examine on the observations from the far eastern and southern sites on the island, located well away from the region of shallow seismicity and any potentially active volcanic system. Caribbean-fixed residual velocity magnitudes range from 2$\pm$2 to 8$\pm$2 mm$/$yr directed approximately west. Although these results must be regarded as preliminary, they are consistent with simple models of elastic strain accumulation along the plate interface.
DE: 1200 GEODESY AND GRAVITY
DE: 1299 General or miscellaneous
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting