In this paper, we are interested in the seismic wave propagation into an uncertain medium. To this end, we performed an ensemble of 400 large-scale simulations that requires 4 million core-hours of CPU time. In addition to the large computational load of these simulations, solving the uncertainty propagation problem requires dedicated procedures to handle the complexities inherent to large dataset size and the low number of samples. We focus on the peak ground motion at the free surface of the 3D domain, and our analysis utilizes a surrogate model combining two key ingredients for complexity mitigation: (i) a dimension reduction technique using empirical orthogonal basis functions, and (ii) a functional approximation of the uncertain reduced coordinates by polynomial chaos expansions. We carefully validate the resulting surrogate model by estimating its predictive error using bootstrap, truncation, and cross-validation proce-dures. The surrogate model allows us to compute various statistical information of the uncertain prediction, including marginal and joint probability distributions, interval probability maps, and 2D fields of global sensitivity indices.
Citation
Sochala, P., De Martin, F., & Le Maître, O. (2020). MODEL REDUCTION FOR LARGE-SCALE EARTHQUAKE SIMULATION IN AN UNCERTAIN 3D MEDIUM. International Journal for Uncertainty Quantification, 10(2), 101–127. doi:10.1615/int.j.uncertaintyquantification.2020031165
Acknowledgements
The work of P. Sochala and F. De Martin has been supported by internal funding of BRGM. The authors are grateful to D. Keyes and P. Thierry for supporting the project “Earthquake Ground Motion Analysis and extreme computing on multi-Petaflops machine” at the KAUST Extreme Computing Research Center. The authors are also thankful to E. Chaljub, E. Maufroy, F. Hollender, and P.-Y. Bard for providing the velocity model data and for the fruitful discussions about the definition of the Mygdonian basin model.
