Graves, Robert W. and Clayton, Robert W.
Modeling path effects in three-dimensional basin structures.
Bulletin of the Seismological Society of America, 82
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Path effects for seismic wave propagation within three-dimensional (3-D) basin structures are analyzed using a reciprocal source experiment. In this experiment, a numerical simulation is performed in which a point source is excited at a given location and then the wave field is propagated and recorded throughout a 3-D grid of points. Using the principle of reciprocity, source and receiver locations are reversed. This allows the modeling of path effects into a particular observation site for all possible source locations using only one simulation. The numerical technique is based on the use of paraxial extrapolators and currently tracks only acoustic waves. However, the method is capable of handling arbitrary media variations; thus, effects due to focusing, diffraction, and the generation of multiple reflections and refractions are modeled quite well.
The application of this technique to model path effects for local earthquakes recorded at stations in the Los Angeles area of southern California indicates the strong influence of the 3-D crustal basins of this region on the propagation of seismic energy. The modeling results show that the Los Angeles, San Fernando, and San Gabriel basins create strong patterns of focusing and defocusing for paths into these stations from various source locations. These simulations correlate well with earthquake data recorded at both stations. By comparing these calculations with earthquake data, we can begin to evaluate the importance of these basin effects on observed patterns of strong ground motions.
|Additional Information:||© 1992 Seismological Society of America.
Manuscript received 19 February 1991.
We would like to thank Amoco Foundation Inc. for the generous fellowship support of R. W. G. during this study. Some of the computations were done on a Convex C1/XP purchased under NSF Grant EAR-8721205. We also thank Donald V. Helmberger and Paul G. Somerville for suggestions to this work. Contribution no. 4988, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California.|
|Funding Agency||Grant Number|
|Amoco Foundation, Inc.||UNSPECIFIED|
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|Other Numbering System Name||Other Numbering System ID|
|Caltech Division of Geological Planetary Sciences||4988|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited On:||11 Oct 2012 15:13|
|Last Modified:||31 Jan 2017 21:29|
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