← Back to Gallery

A Induced Seismicity Non-Ergodic Ground Motion Prediction Equation (GMPE) in the Oklahoma Region

We present a non-ergodic GMPE for shallow induced earthquakes in the Oklahoma region. The high-rate of earthquakes in the Oklahoma region provides the data needed to constrain the source-, path- and site-specific aspects of the GMM. The selected data set includes earthquakes with magnitudes from M 3.0 to 5.0, rupture distances less than 50 km and a minimum of five recordings per earthquake. Using the Abrahamson et al. (2014) crustal GMM adjusted for regional induced events as the reference ergodic model, we derive nonergodic adjustment terms based on a varying-coefficient model (VCM, following Landwehr et al., 2016) and the cell-specific approach by Kuehn et al. (2019) for anelastic attenuation. The VCM models a source-specific constant, as well as a site-specific constant and Vs30-scaling using a Gaussian process. The parameters required for the nonergodic adjustment terms (variances and length-scales of the Gaussian process and cell-specific attenuation coefficients) are estimated via Bayesian inference. We pay close attention to the uncertainty in all of the parameters of the model.

In a forward application, at different coordinates the estimated spatially varying coefficients allow to calculate both the median and epistemic uncertainty for the predicted ground-motion parameter as it varies spatially across the region. For coordinate locations that have no data, the non-ergodic model returns to the ergodic mean model but with large epistemic uncertainty.

Presenting Author: Nicolas M. Kuehn

Additional Authors