Ground Motion Prediction Equations for the Central and Eastern United States

Abstract:

New ground motion prediction equations (GMPE) G15 model for the Central and Eastern United States (CEUS) is presented. It is based on the modular filter based approach developed by Graizer and Kalkan (2007, 2009) for active tectonic environment in the Western US (WUS). The G15 model is based on the NGA-East database for the horizontal peak ground acceleration and 5%-damped pseudo spectral acceleration RotD50 component (Goulet et al., 2014). In contrast to active tectonic environment the database for the CEUS is not sufficient for creating purely empirical GMPE covering the range of magnitudes and distances required for seismic hazard assessments. Recordings in NGA-East database are sparse and cover mostly range of M<6.0 with limited amount of near-fault recordings. The functional forms of the G15 GMPEs are derived from filters—each filter represents a particular physical phenomenon affecting the seismic wave radiation from the source. Main changes in the functional forms for the CEUS relative to the WUS model (Graizer and Kalkan, 2015) are a shift of maximum frequency of the acceleration response spectrum toward higher frequencies and an increase in the response spectrum amplitudes at high frequencies. Developed site correction is based on multiple runs of representative V_S30 profiles through SHAKE-type equivalent-linear programs using time histories and random vibration theory approaches. Site amplification functions are calculated for different V_S30 relative to hard rock definition used in nuclear industry (Vs=2800 m/s). The number of model predictors is limited to a few measurable parameters: moment magnitude M, closest distance to fault rupture plane R, average shear-wave velocity in the upper 30 m of the geological profile V_S30, and anelastic attenuation factor Q₀. Incorporating anelastic attenuation Q₀ as an input parameter allows adjustments based on the regional crustal properties. The model covers the range of magnitudes 4.0<M<8.5, distances of 0<R<1000 km, S-wave velocities of 450<V_S30<2800 m/s and frequencies of 0.1<f<100 Hz. Comparison are made of the G15 model with existing CEUS GMPEs including the new NGA-East model. In general, the G15 model produces results lower than the median EPRI 2013 model at high frequencies (f>10 Hz) and is within the range of other models for frequencies lower than 2.5 Hz