HR: 0800h
AN: DI31A-0260    [Abstracts]
TI: A New Approach to Determine the Inner-Core Rotation
AU: * Lindner, D
EM: lindner2@uiuc.edu
AF: Department of Geology, University of Illinois at Urbana-Champaign, 1301 W Green Street, Urbana, IL 61801, United States
AU: Song, X
EM: xsong@uiuc.edu
AF: Department of Geology, University of Illinois at Urbana-Champaign, 1301 W Green Street, Urbana, IL 61801, United States
AU: Ma, P
EM: pingma@uiuc.edu
AF: Department of Statistics, University of Illinois at Urbana-Champaign, 725 South Wright Street, Champaign, IL 61820, United States
AU: Christensen, D H
EM: doug@giseis.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775, United States
AB: We present a new approach to gain insight into the inner core rotation by separating the underlying structure from its time evolution. This is achieved by fitting existing seismic data with a smoothing spline analysis of variance model, which is implemented in the statistics package R. This model allows us to separate the structure from its time evolution without any a priori constraints, and also to estimate the error of the fit. Preliminary testing with synthetic datasets that feature both a non-linear structure and variable rotation and share existing earthquakes and stations geometry prove the success of this approach. The mantle and time-dependent inner-core structures are fitted simultaneously and can be separated. Applying this method to existing seismic data from S. Sandwich Islands earthquakes to Alaskan stations suggests an apparent change in the rotation rate of the inner-core within the last 20 years, implying a non-zero acceleration. We will include our newly acquired seismic data from the PASSCAL experiment ARCTIC in northern Alaska, which will increase our time-resolution as well as data coverage of the inner core structure. The results and possible implications on the inner-core rotation and its possible acceleration will be reported.
UR: http://www.geology.uiuc.edu/~xsong/arctic/arctic.html
DE: 1212 Earth's interior: composition and state (7207, 7208, 8105, 8124)
DE: 1213 Earth's interior: dynamics (1507, 7207, 7208, 8115, 8120)
DE: 8124 Earth's interior: composition and state (1212, 7207, 7208, 8105)
SC: Study of the Earth's Deep Interior [DI]
MN: 2007 Fall Meeting