HR: 0800h
AN: S11B-0564    [Abstracts]
TI: Mantle Anisotropy in Northern Alaska: Analysis of ARCTIC Seismic Data Using Shear Wave Splitting
AU: * Litherland, M
EM: mairi@rice.edu
AF: Department of Earth Science Rice University, M.S. 126, P.O. Box 1892, Houston, TX 77251,
AU: Christensen, D
EM: doug@giseis.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, P.O. Box 757320, Fairbanks, AK 99775,
AU: Song, X
EM: xsong@uiuc.edu
AF: Department of Geology, 1301 W Green St., Urbana, IL 61801,
AB: Shear wave splitting observations from teleseismic SKS phases are used to infer the anisotropy under northern Alaska. SKS waveforms were examined from the ARCTIC PASSCAL experiment, which consisted of 15 broadband seismic stations. These stations were deployed between 2004 and 2007 with twelve in a 550 km north/south line between Fairbanks and the Arctic Ocean and three distributed in a sparse east/west line from Fairbanks to the Bering Sea. Results indicate that fast directions are mostly oriented in a slightly north of east direction for all stations, except the furthest west station at Nome which showed a nearly north/south fast direction. The time delays range from approximately 0.5 to 1.5 seconds, however stations in the Brooks Range yielded somewhat more northerly fast directions with higher splitting delay times. These fast directions reflect the anisotropy in the upper mantle and likely indicate that there is a strong regional east-northeast/west-southwest direction of the flow in the upper mantle under central and northern Alaska. This direction is generally parallel to crustal structures, such as mountain ranges and major faults. This orientation is also similar to the fast directions observed in the Alaska Range from the BEAAR PASSCAL experiment, but orthogonal to fast directions south of the Alaska Range.
DE: 7200 SEISMOLOGY
DE: 7203 Body waves
DE: 7208 Mantle (1212, 1213, 8124)
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
SC: Seismology [S]
MN: 2007 Fall Meeting