Exciting news! We're transitioning to the Statewide California Earthquake Center. Our new website is under construction, but we'll continue using this website for SCEC business in the meantime. We're also archiving the Southern Center site to preserve its rich history. A new and improved platform is coming soon!

Inclusion of Frequency-Dependent Spatial Correlation into the SDSU Broadband Ground-Motion Generation Method

Nan Wang, Rumi Takedatsu, Kim B. Olsen, & Steven M. Day

Published August 14, 2019, SCEC Contribution #9643, 2019 SCEC Annual Meeting Poster #014

Seismic losses (such as disruption of distributed infrastructure and losses to portfolios of structures) are typically dependent upon the regional distribution of ground-motion intensities, rather than the intensity at only a single site. Ground motion time series recorded at stations separated by up to a few tens of kilometers show a frequency-dependent spatial coherency structure, and measures such as PGVs, PGAs and peak spectral accelerations are found to be correlated. Quantifying ground motion over a spatially-distributed region is therefore important and requires information on the correlation between the ground motion intensities at different sites during a single event, where the spatial correlation can be significant within 50 km. Exclusion of spatial correlation in ground motion simulations can result in an under-estimation of the seismic risk. The San Diego State University (SDSU) module on the Southern California Earthquake Center (SCEC) Broadband Platform (BBP) is a hybrid method that merges low-frequency deterministic synthetics and high-frequency stochastic scattering functions. We have implemented frequency-dependent spatial correlation into the SDSU method on the SCEC BBP using a post-processing method. This method makes use of a two-dimensional Gaussian random variable that has covariance corresponding to the spatial cross-correlation model developed from the Pacific Earthquake Engineering Research Center (PEER) Next Generation Attenuation (NGA) West2 database. Our results for the Loma Prieta, CA, event show that the frequency-dependent spatial correlation in our broadband synthetics compares well to that estimated from seismic observations.

Wang, N., Takedatsu, R., Olsen, K. B., & Day, S. M. (2019, 08). Inclusion of Frequency-Dependent Spatial Correlation into the SDSU Broadband Ground-Motion Generation Method. Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
Ground Motions