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Advancement in Source Estimation Techniques Using Broadband Regional Seismograms

Zhu, Lupei and Helmberger, Donald V. (1996) Advancement in Source Estimation Techniques Using Broadband Regional Seismograms. Bulletin of the Seismological Society of America, 86 (5). pp. 1634-1641. ISSN 0037-1106.

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One important constraint on source retrieval from regional seismograms comes from the amplitude difference between various phases (such as Pnl/surface wave, SV/SH). Because the misfit errors used in some waveform inversions are normalized by the data and synthetics, the amplitude information in the data has not been fully utilized. In this article, we modify the "cut and paste" source estimation technique (Zhao and Helmberger, 1994) by removing this type of normalization. It is shown that the modified method increases the stability and resolution of inversion. When multiple stations at different distance ranges are used, a distance scaling factor is introduced to compensate for the amplitude decay with distance. By applying the technique to the TERRAscope data, we have determined source mechanisms and depths of 335 southern Californian events with M_L ≧ 3.5. The amplitude decays with distance are r^(1.13) for Pnl, r^(0.55) for Love waves, and r^(0.74) for Rayleigh waves. In contrast to generally shallow source depths reported by the southern California short period network, the depth distribution from waveform inversion shows a strong peak around 12 km with few earthquakes occurring above 5 km and below 20 km.

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Additional Information:© 1996 Seismological Society of America. Manuscript received 12 April 1996. The authors thank H. Kanamori, E. Hauksson, T. Melbourne, and C. Scrivner at Seismological Laboratory of Caltech for their helpful comments on the manuscript. We also benefited from the waveform data achieve of TERRAscope network operated by the TERRAscope project at Caltech. This research was supported by SCEC, Contract No. 569933, NSF EAR 89-20136, and by the Department of Defense as monitored by the Air Force Office of Scientific Research under Contract F19628-95-C-0096. Contribution No. 5670, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California. Southern California Earthquake Center Contribution No. 324.
Funding AgencyGrant Number
Southern California Earthquake Center (SCEC)569933
NSFEAR 89-20136
Department of DefenseF19628-95-C-0096
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Caltech Division of Geological and Planetary Sciences5670
Southern California Earthquake Center324
Issue or Number:5
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36507
Deposited On:23 Jan 2013 18:47
Last Modified:03 Oct 2019 04:38

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