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Comparative validation of a set of physics-based simulations of the 2008 Chino Hills earthquake using different velocity models

Ricardo Taborda, & Jacobo Bielak

Published July 2013, SCEC Contribution #1889

We present a set of ground-motion simulations of the 2008 Mw 5.4 Chino
Hills earthquake using different seismic-velocity models available for southern
California. The simulations are tailored for a maximum frequency of 4 Hz and a minimum
shear-wave velocity of 200 m=s. We use the community models developed by
the Southern California Earthquake Center, CVM-S and CVM-H. In the case of
CVM-H, we use two available alternatives, with and without considering the geotechnical
layers (GTL). We compare the simulation results obtained with the models
against each other and validate the synthetics with recordings obtained at more than
300 stations. The comparisons are used to gain insight into the sensitivity of the results
to differences in the models and to make conclusions about the strengths of each model’s
description of the crustal structure and the GTL in the region. The validation is
done using a goodness-of-fit (GOF) criterion. We find the GOF values show a better
match at frequencies below 1 Hz, within the basins, and below 0.5 Hz in general. The
models, however, do not converge at frequencies lower than 0.5 Hz, and the areas
where each model leads to better results do not always coincide. The synthetics start
to deviate significantly from observations at frequencies above 1 and 2 Hz, although
very good agreement with data can still be found at individual locations, even at the
higher frequencies. CVM-S yields the best results at frequencies up to 0.25 Hz. Our
results reveal significant sensitivity of the ground motion to the differences in the
structural representation of basins and shallow layers in the models. This indicates
the models need to be cross referenced. We close by offering suggestions on the type
of improvements that could be adopted in the future.

Taborda, R., & Bielak, J. (2013, 7). Comparative validation of a set of physics-based simulations of the 2008 Chino Hills earthquake using different velocity models. Oral Presentation at CIG/QUEST/IRIS Joint Workshop on Seismic Imaging of Structure and Source. doi: 10.1785/0120130266.