HR: 0800h
AN: G51A-0067    [Abstracts]
TI: 2003-2004 Campaign GPS Geodetic Monitoring of Surface Deformation Proximal to Volcanic Centers, Commonwealth of Dominica, Lesser Antilles.
AU: * Davidson, R T
EM: rtdypb@umr.edu
AF: Department of Geological Sciences and Engineering, 125 McNutt Hall University of Missouri-Rolla, Rolla, MO 65409 United States
AU: Turner, H L
EM: hturner@uark.edu
AF: Department of Geosciences, 113 Ozark Hall University of Arkansas, Fayetteville, AR 72701 United States
AU: Blessing, B C
EM: bcblessi@mtu.edu
AF: Department of Geological Engineering and Sciences, Michigan Tech, 630 Dow Environmental Sciences and Engineering Building 1400 Townsend Drive, Houghton, MI 49931-1295 United States
AU: Parra, J
EM: paplotl@hotmail.com
AF: Geological Sciences Department, California State Polytechnic University - Pomona, 3801 W. Temple Ave, Pomona, CA 91768 United States
AU: Fitzgibbon, K
EM: kfitzgi@uark.edu
AF: Department of Geosciences, 113 Ozark Hall University of Arkansas, Fayetteville, AR 72701 United States
AU: Jansma, P
EM: pjansma@uark.edu
AF: Department of Geosciences, 113 Ozark Hall University of Arkansas, Fayetteville, AR 72701 United States
AU: Mattioli, G
EM: mattioli@uark.edu
AF: Department of Geosciences, 113 Ozark Hall University of Arkansas, Fayetteville, AR 72701 United States
AB: The Commonwealth of Dominica, located midway along the Lesser Antilles island arc, is home to several (at least eight) potentially active volcanic centers. Spurred by recent seismic crises on the island - in the south from 1998-2000 and in the north in 2003 - twelve GPS monuments were installed in two field campaigns in 2001 and 2003. All twelve sites, along with five of six newly installed sites, were occupied continuously for ~2.5 or more UTC days in 2004 using Ashtech Z-12 dual-frequency, code-phase receivers and choke ring antenna to assess the highly complex and possibly interconnected volcanic systems of Dominica. We examine data from the 2003-2004 epochs because of the highly variable, shallow seismicity preceding this period. This way one can potentially isolate the changes that occurred without the data from previous observations influencing the results. Although only two epochs have been included, data quality and reliability can be established from sites distant from volcanic centers, as such sites show consistent velocities from all three epochs of observation over the 2001-2004 period. Between 2003 and 2004, multiple sites show velocities that are inconsistent with a simple tectonic interpretation of elastic strain accumulation along the plate interface. Sites located in the vicinity of the volcanic centers in the south central part of the island are moving faster than the 3 epoch 2001-2004 average of the velocities, which is approximately 7mm/year. The four sites at which greater movement has been noted have velocities ranging from approximately 10 to 27 mm/year. We note that the largest surface deformation signal is seen in the south during the same period when the shallow seismicity was at a maximum in the north of the island. While the spatial distribution of sites remains sparse and the velocities relatively imprecise, the preliminary results may indicate shallow magmatic emplacement, geothermal fluctuations, or structural instability in that part of the island.
DE: 8499 General or miscellaneous
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting