Surface Wave Path Corrections and Source Inversions in Southern California

Ying Tan, Teh-Ru Song, Shengji Wei, & Donald V. Helmberger

Published December 2010, SCEC Contribution #1604

The Cut-and-Paste (CAP) methodology for recovering source parameters has proven useful in many regions. The method uses a library of 1D Green’s functions which are broken into segments and matched to observations where adjustable timing shifts and path corrections are found along with the source parameters. If these path corrections are known, we can use the same method but recover both mechanism and location, a procedure we call CAPloc. Here, we use 160 events with known locations to develop maps of Rayleigh and Love wave delays for Southern California using the TriNet array. We assume a 15 km thick seismogenic layer which is uniform in depth but can vary laterally in 10 km grids and use tomography to define the velocity variation which is up to 15%. Synthetics generated from 2D cross-sections connecting source and station pairs indicates that 1D synthetics are sufficient in modeling but simply shifted in time for most paths. This simplification allows source inversion for both mechanisms and locations to be easily obtained by grid-search. We test the usefulness of two station inversions involving PAS and GSC which have waveform data since 1960 against the full-array with considerable success when the events are bracketed.

Tan, Y., Song, T., Wei, S., & Helmberger, D. V. (2010). Surface Wave Path Corrections and Source Inversions in Southern California . Bulletin of the Seismological Society of America, 100(6), 2891-2904. doi: 10.1785/0120090063.