HR: 0800h
AN: S41B-0566    [Abstracts]
TI: Wave Gadiometry for USArray
AU: * Liang, C
EM: cliang1@memphis.edu
AF: Center For Earthquake Research and Information, University of Memphis, 3876 Central Ave, Memphis, TN 38152, United States
AU: Langston, C A
EM: clangstn@memphis.edu
AF: Center For Earthquake Research and Information, University of Memphis, 3876 Central Ave, Memphis, TN 38152, United States
AB: Wave gradiometry is a new array analysis technique that makes use of the wave amplitude variation across a small aperture array to find the phase velocity, wave directionality and geometrical spreading. In this study we apply wave gradiometry to USArray data for the Western North America. A weighted inversion method is introduced to compute spatial gradients that are linearly related to the station spacing and wave amplitude differences based on a first order of Taylor series approximation. The amplitude differences of station pairs with large truncation errors due to higher order terms are down-weighted in the inversion equations. The reduced time method is also effectively applied in the data processing under the assumption that the media inside of the sub- array is homogeneous. Synthetic waveforms using a wave number integration method and Gaussian plane waves are used to successfully test the process. Waveforms from the Kurile Islands earthquake of 13 January 2007 are analyzed. Preliminary results show that the average phase velocity of 100-125 seconds Rayleigh waves is about 4.0 km/s with the prominent feature that the Basin and Range and the west coast are dominated by velocity lows and highs, respectively. The wave directionality map reveals refraction into the continent at the plate boundary. Future work will include using waveforms of earthquakes from different directions and distances to understand the variations seen in the parameter maps derived by wave gradiometry and then use results in tomographic structure studies.
DE: 7200 SEISMOLOGY
DE: 7218 Lithosphere (1236)
DE: 7255 Surface waves and free oscillations
DE: 7260 Theory
DE: 7294 Seismic instruments and networks (0935, 3025)
SC: Seismology [S]
MN: 2007 Fall Meeting