Reference frequency of teleseismic body waves

S. Oki, Y. Fukao, M. Obayashi

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Anelasticity of the Earth causes physical dispersion of seismic waves. The appropriate choice of reference frequency is important to determine arrival times of body waves, especially later arrival times, from broadband seismograms by fitting observed to synthetic waveforms. Our question is how to choose the reference frequency of physical dispersion, fo, consistent with the extensive data sets of hand-picked body wave arrival times compiled through the long history of seismology. Setting the reference frequency to be the conventional 1 Hz, we measured S-P differential travel times by waveform fitting. We found a systematic discrepancy between the measured and hand-picked S-P times that can be removed by changing fo from 1 to 2 Hz. This change of fo requires a correction in Q of the PREM model: (1 if Q is strictly frequency-independent, we need a 15% increase in Q value or (2) if Q is fixed to the value given by PREM at a period of 200 s, we need to introduce a small frequency dependence in Q, where the dependence is expressed by the power law with an exponent of 0.04.

Original languageEnglish
JournalJournal of Geophysical Research B: Solid Earth
Volume109
Issue number4
DOIs
Publication statusPublished - 2004 Apr 10
Externally publishedYes

Fingerprint

teleseismic wave
body wave
arrival time
Seismology
Seismic waves
Travel time
arrivals
anelasticity
frequency dependence
Earth (planet)
seismology
seismogram
waveforms
seismic wave
travel time
power law
seismograms
seismic waves
travel
history

Keywords

  • Anelasticity
  • Reference frequency
  • Teleseismic body waves

ASJC Scopus subject areas

  • Oceanography
  • Astronomy and Astrophysics
  • Atmospheric Science
  • Space and Planetary Science
  • Earth and Planetary Sciences (miscellaneous)
  • Geophysics
  • Geochemistry and Petrology

Cite this

Reference frequency of teleseismic body waves. / Oki, S.; Fukao, Y.; Obayashi, M.

In: Journal of Geophysical Research B: Solid Earth, Vol. 109, No. 4, 10.04.2004.

Research output: Contribution to journalArticle

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AB - Anelasticity of the Earth causes physical dispersion of seismic waves. The appropriate choice of reference frequency is important to determine arrival times of body waves, especially later arrival times, from broadband seismograms by fitting observed to synthetic waveforms. Our question is how to choose the reference frequency of physical dispersion, fo, consistent with the extensive data sets of hand-picked body wave arrival times compiled through the long history of seismology. Setting the reference frequency to be the conventional 1 Hz, we measured S-P differential travel times by waveform fitting. We found a systematic discrepancy between the measured and hand-picked S-P times that can be removed by changing fo from 1 to 2 Hz. This change of fo requires a correction in Q of the PREM model: (1 if Q is strictly frequency-independent, we need a 15% increase in Q value or (2) if Q is fixed to the value given by PREM at a period of 200 s, we need to introduce a small frequency dependence in Q, where the dependence is expressed by the power law with an exponent of 0.04.

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