ShakeOut-D: Ground motion estimates using an ensemble of large earthquakes on the southern San Andreas fault with spontaneous rupture propagation

We simulate ground motion in southern California from an ensemble of 7 spontaneous rupture models of large (Mw7.8) northwest‐propagating earthquakes on the southern San Andreas fault (ShakeOut‐D). Compared to long‐period spectral accelerations from the Next Generation Attenuation (NGA) empirical rel...

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Bibliographic Details
Published in:Geophysical research letters 2009-02, Vol.36 (4), p.L04303-n/a
Main Authors: Olsen, K. B., Day, S. M., Dalguer, L. A., Mayhew, J., Cui, Y., Zhu, J., Cruz-Atienza, V. M., Roten, D., Maechling, P., Jordan, T. H., Okaya, D., Chourasia, A.
Format: Article
Language:English
Subjects:
Computational seismology
Earth sciences
Earth, ocean, space
Earthquake ground motions and engineering seismology
earthquake rupture dynamics
Earthquake source observations
Earthquakes
Exact sciences and technology
finite difference simulations
ground motion simulations
Mantle
Seismology
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Summary:We simulate ground motion in southern California from an ensemble of 7 spontaneous rupture models of large (Mw7.8) northwest‐propagating earthquakes on the southern San Andreas fault (ShakeOut‐D). Compared to long‐period spectral accelerations from the Next Generation Attenuation (NGA) empirical relations, ShakeOut‐D predicts similar average rock‐site values (i.e., within roughly their epistemic uncertainty), but significantly larger values in Los Angeles and Ventura basins due to wave‐guide focusing effects. The ShakeOut‐D ground motion predictions differ from those of a kinematically parameterized, geometrically similar, scenario rupture: (1) the kinematic rock‐site predictions depart significantly from the common distance‐attenuation trend of the NGA and ShakeOut‐D results and (2) ShakeOut‐D predictions of long‐period spectral acceleration within the basins of the greater Los Angeles area are lower by factors of 2–3 than the corresponding kinematic predictions. We attribute these differences to a less coherent wavefield excited by the complex rupture paths of the ShakeOut‐D sources.
ISSN:0094-8276
1944-8007
DOI:10.1029/2008GL036832