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Published February 1994 | Published
Journal Article Open

Source Estimation from Broadband Regional Seismograms


Recently developed source inversion techniques do not take full advantage of the broadband nature of regional seismograms. The reason is that Green's functions generated from flat-layered models are not correct for the complicated propagational phenomena associated with realistic crustal structure. The inversion is usually performed by removing short periods and inverting only selected portions of the records. In this article, we introduce a source estimation technique that allows for better use of the entire broadband record when only imperfect Green's function are available. The procedure desensitizes the timing between the principal crustal arrivals by fitting portions of the Green's functions independently. The preferred source is the orientation that minimizes the average L1 and L2 norms in term of the four parameters, M_0, strike, dip, and rake. The L2 error emphasizes the longer period surface waves while the L1 error weights the shorter period body waves. We obtain estimates of duration by modeling long period and broadband signals. The depth determination can be obtained directly from the surface reflected phases sP_mP or sS_mS or by cycling through the depth-dependent Green's functions. In addition to the source parameters, we obtain "δt" phase alignments shifts that can be used as Green's function corrections for relocating other events or as a guide to deriving new crustal models.

Additional Information

© 1994 by the Seismological Society of America. Manuscript received 10 February 1993. We thank Doug Dreger for ideas on source inversion and Hiroo Kanamori for efforts in producing these TERRAscope records. We also thank C. A. Langston and R. B. Herrmann for suggestions and comments. This research was supported by a Southern California Earthquake Center grant SCEC-USC 569933 of NSF EAR 89-20136 and by the Department of Defense as monitored by the Air Force Office of Scientific Research under the contract F49620-93-1-0221. Contribution No. 5245, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California.

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August 20, 2023
August 20, 2023