The Relation Between Ground Motion, Earthquake Source Parameters, and Attenuation: Implications for Source Parameter Inversion and Ground Motion Prediction Equations

Itzhak Lior*, Alon Ziv

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Theoretical equations relating the root-mean-square (rms) of the far-field ground motions with earthquake source parameters and attenuation are derived for Brune's omega-squared model that is subject to attenuation. This set of model-based predictions paves the way for a completely new approach for earthquake source parameter inversion and forms the basis for new physics-based ground motion prediction equations (GMPEs). The equations for ground displacement, velocity, and acceleration constitute a set of three independent equations with three unknowns: the seismic moment, the stress drop, and the attenuation parameter. These are used for source parameter inversion that circumvents the time-to-frequency transformation. Initially, the two source parameters and the attenuation constant are solved simultaneously for each seismogram. Sometimes, however, this one-step inversion results in ambiguous solutions. Under such circumstances, the procedure proceeds to a two-step approach, in which a station-specific attenuation parameter is first determined by averaging the set of attenuation parameters obtained from seismograms whose one-step inversion yields well-constrained solutions. Subsequently, the two source parameters are solved using the averaged attenuation parameter. It is concluded that the new scheme is more stable than a frequency domain method, resulting in considerably less within-event source parameter variability. The above results together with rms-to-peak ground motion relations are combined to give first-order GMPEs for acceleration, velocity, and displacement. In contrast to empirically based GMPEs, the ones introduced here are extremely simple and readily implementable, even in low-seismicity regions, where the earthquake catalog lacks strong ground motion records.

Original languageAmerican English
Pages (from-to)5886-5901
Number of pages16
JournalJournal of Geophysical Research: Solid Earth
Volume123
Issue number7
DOIs
StatePublished - Jul 2018
Externally publishedYes

Bibliographical note

Publisher Copyright:
©2018. American Geophysical Union. All Rights Reserved.

Keywords

  • attenuation
  • ground motion prediction
  • inversion
  • source parameters
  • theoretical seismology

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