HR: 0800h
AN: T11C-1277    [Abstracts]
TI: Validating Three-dimensional Velocity Models in China and East-Asia for use in Regional Seismic Event Location
AU: * Begnaud, M L
EM: mbegnaud@lanl.gov
AF: Los Alamos National Laboratory, P.O. Box 1663, MS F665, Los Alamos, NM 87545 United States
AU: Rowe, C A
EM: char@lanl.gov
AF: Los Alamos National Laboratory, P.O. Box 1663, MS F665, Los Alamos, NM 87545 United States
AU: Steck, L K
EM: lsteck@lanl.gov
AF: Los Alamos National Laboratory, P.O. Box 1663, MS F665, Los Alamos, NM 87545 United States
AB: We have developed a three-dimensional (3D) a priori geophysical model for the China/East Asia (CEA) region and are using it to construct 3D travel-time tables for seismic event relocation. Validation of this 3D model involves comparison of travel times to other 3D models, both a priori and tomograhic, as well as to observed arrival times from ground truth events. The CEA a priori model is constructed by patching one-dimensional velocity models from previous studies together and adjusting them to conform to known basin and crust thickness values. This type of model aids in the view of geophysical properties over a larger region than typical tomographic models can provide. Using several ray-tracing algorithms, we will produce fine-scale travel-time tables for various stations within the CEA model and compare the travel times to both tomographic models and other a priori models. The 3D travel-time tables will be used to relocate ground truth events for models and determine how these tables affect the regional locations. 3D models do display significant variation in velocities when compared to global one-dimensional models, especially for crust and upper-mantle structure. Our goal is to utilize these 3D variations and apply the 3D travel times on large portions of a seismic catalog to determine their effect. The use of 3D travel-time tables is still being investigated as a viable, operational alternative to one-dimensional models with corrections. As model resolution and accuracy improve, their use can continue to benefit regional event relocation results, but the trade-off with computational load and efficiency must be weighed for the more detailed parameterizations.
DE: 7230 Seismicity and seismotectonics
DE: 7260 Theory and modeling
DE: 7205 Continental crust (1242)
DE: 7218 Lithosphere and upper mantle
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting