Ground-Motion Simulation and Validation of the 2008 Chino Hills, California, Earthquake Using Different Velocity Models

Ricardo Taborda, & Jacobo Bielak

Published July 1, 2014, SCEC Contribution #1798

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 by SCEC's partners at Harvard University (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 geotechnical layers in the region. The validation is done using a goodness-of-fit (GOF) criterion. We find that 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 that the models need to be cross-referenced. We close by offering suggestions on the type of improvements that could be adopted in the future.

Citation
Taborda, R., & Bielak, J. (2014). Ground-Motion Simulation and Validation of the 2008 Chino Hills, California, Earthquake Using Different Velocity Models. Bulletin of the Seismological Society of America, 104(4), 1876-1898. doi: 10.1785/0120130266.

Related Projects & Working Groups
Computational science, Ground-Motion Prediction, Earthquake Engineering Implementation Interface, Community Modeling Environment