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.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 1212 Earth's interior: composition and state (7207;
- 1213 Earth's interior: dynamics (1507;
- 8124 Earth's interior: composition and state (1212;