Estimation of Ground Motion Variability in the CEUS

Sanaz Rezaeian, Xiaodan Sun, Brandon Clayton, & Stephen Hartzell

Published August 14, 2017, SCEC Contribution #7625, 2017 SCEC Annual Meeting Poster #258

The Next Generation Attenuation for Eastern U.S. (NGA-East) project (Goulet et al., 2017) has adopted the Sammon’s mapping approach for estimating ground motion uncertainties in the Central and Eastern United States (CEUS). Although this approach offers a convenient way of rendering a complex problem into a simple graphical form, the physics of the problem are obscured. We estimate the ground motion uncertainty in the CEUS by using two alternative simulation methods (Rezaeian et al., 2017): a deterministic physics-based method, and a stochastic method. Both of these methods have been previously used to simulate motions for the 2011 M 5.8 Mineral, Virginia, and the 2001 M 7.6 Bhuj, India (a tectonic analog for CEUS), earthquakes. Utilizing the NGA-East ground motion database, we model additional motions for the CEUS, and then simulate scenario M 6.0, 6.5, 7.0, 7.5, and 8.0 events. To estimate the uncertainty using the physics-based method, we use several realizations for the model parameters of mechanism, slip, stress drop, rupture velocity, source depth, Q, and 1D velocity structure. Because these variations are a subset of all possible model variations, the resulting uncertainty is regarded as a lower bound estimate. The stochastic method generates ground motions using a set of 6 nonstationary parameters, describing the Arias intensity, duration, frequency and bandwidth of the motion. Each parameter is assigned a probability distribution calibrated using the CEUS database. Because a full distribution is assigned to each parameter, we regard the resulting uncertainty as an upper bound estimate. Our median amplitudes for PGA, and PSA at a variety of periods compare well with NGA-East. The variability in ground motion is examined as a function of magnitude, distance, and period. The average log-normal standard deviation from the physics-based and the stochastic methods, considered to be lower and upper bounds, are compared to NGA-East.

- Goulet, C., Y. Bozorgnia, N. Kuehn, L. Al Atik, R. Youngs, R. Graves, and G. Atkinson (2017). NGA-East Ground-Motion Models for the U.S. Geological Survey National Seismic Hazard Maps. PEER Report 2017/03, Pacific Earthquake Engineering Research, Berkeley, CA
- Rezaeian, S., S. Hartzell, X. Sun, and C. Mendoza (2017). Simulation of Earthquake Ground Motions in the Eastern United States Using Deterministic Physics‐Based and Site‐Based Stochastic Approaches, Bulletin of the Seismological Society of America, 107, 149-168

Key Words
Ground Motion Simulation, Uncertainty, Central and Eastern U.S.

Citation
Rezaeian, S., Sun, X., Clayton, B., & Hartzell, S. (2017, 08). Estimation of Ground Motion Variability in the CEUS. Poster Presentation at 2017 SCEC Annual Meeting.

Related Projects & Working Groups
Ground Motions