HR: 1340h
AN: T33A-1357    [Abstracts]
TI: Seismic Anisotropy at the Krafla Geothermal Field in Northern Iceland
AU: * Thompson, E
EM: erict@unc.edu
AF: University of North Carolina, Department of Geological Sciences CB #3315, Mitchell Hall, Chapel Hill, NC 27599-3315 United States
AU: Rial, J A
EM: jar@email.unc.edu
AF: University of North Carolina, Department of Geological Sciences CB #3315, Mitchell Hall, Chapel Hill, NC 27599-3315 United States
AU: Lees, J M
EM: jonathan_lees@unc.edu
AF: University of North Carolina, Department of Geological Sciences CB #3315, Mitchell Hall, Chapel Hill, NC 27599-3315 United States
AU: Shalev, E
EM: shalev@duke.edu
AF: Duke University, Nicholas School of the Environment & Earth Sciences Division of Earth & Ocean Sciences Box 90227, Durham, NC 27708-0235 United States
AU: Onacha, S
EM: onacha@duke.edu
AF: Duke University, Nicholas School of the Environment & Earth Sciences Division of Earth & Ocean Sciences Box 90227, Durham, NC 27708-0235 United States
AU: Kahn, D
EM: dsk6@duke.edu
AF: Duke University, Nicholas School of the Environment & Earth Sciences Division of Earth & Ocean Sciences Box 90227, Durham, NC 27708-0235 United States
AU: Malin, P E
EM: malin@duke.edu
AF: Duke University, Nicholas School of the Environment & Earth Sciences Division of Earth & Ocean Sciences Box 90227, Durham, NC 27708-0235 United States
AB: We deployed an array twenty PASSCAL L-28 4.5-Hz sensors for forty days during the summer of 2004 at the Krafla Geothermal field. During this time, twenty GeoSpace 1-Hz instruments recorded the seismicity for fifteen days. The Krafla Geothermal field is located approximately 60 km East of Akureyri in northern Iceland. The arrays recorded approximately 5 micro-earthquakes per day at a sampling rate of 500 Hz. This high sampling rate is required to exploit newly developed theories on the frequency-dependence of shear-wave splitting (SWS). The array covered an area approximately 5 km North/South by 4 km East/West. During the experiment, the re-injection of water into the geothermal reservoir was halted for ten days during which seismic activity decreased. When injection resumed, seismic activity returned to its previous intensity. We use SWS measurements to image fracture locations, sizes, and orientations in the geothermal field. These fractures control the directions of fluid migration in the subsurface. This information will aid engineers in locating productive drill sites. This will decrease the cost of geothermal exploration, hopefully making this clean source of energy economically competitive with more traditional forms of energy.
DE: 7230 Seismicity and seismotectonics
DE: 7203 Body wave propagation
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting