HR: 11:05h
AN: S52B-04    [Abstracts]
TI: Integrating global and regional datasets for tomography in North America
AU: * Nettles, M
EM: nettles@eps.harvard.edu
AF: Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138
AU: Dziewo\'{n}ski, A M
EM: dziewons@eps.harvard.edu
AF: Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138
AB: The velocity structure of the upper mantle under North America is of great interest as the USArray project's deployment of a dense grid of broadband seismographs begins. The data from the stations of \linebreak USArray will provide a regional-scale complement to the large volume of high-quality seismic data now available from the Global Seismographic Network of the Incorporated Research Institutions for Seismology. We explore approaches for combining regional and global datasets for tomography of the North American upper mantle. We use a large dataset of surface-wave phase-delay measurements (35~$\leq T \leq$~350~s) made at stations of the IRIS GSN, the U.S. National Seismic Network (USNSN), and the Canadian National Seismograph Network (CNSN). We supplement this dataset with phase-delay measurements made at a selected set of PASSCAL array deployments, including MOMA, BEAAR, and RISTRA. We determine a regional model of the three-dimensional radially anisotropic shear velocity structure under North America that is consistent with long-wavelength, global models of the upper mantle, but that resolves structure on a wavelength of a few hundred kilometers throughout most of the continent. The correspondence between major geological features and those imaged in our mantle model is generally good. Radial anisotropy is observed to be weaker under cratonic regions than under the Basin and Range, where the amplitude of radial anisotropy reaches 4--6%.
DE: 7200 SEISMOLOGY
DE: 7218 Lithosphere and upper mantle
SC: Seismology [S]
MN: 2004 AGU Fall Meeting