Simulation of Earthquake Ground Motions in the Eastern United States Using Deterministic Physics-Based and Site-Based Stochastic Approaches

Earthquake ground-motion recordings are scarce in the central and eastern United States (CEUS) for large-magnitude events and at close distances. We use two different simulation approaches, a deterministic physics-based method and a site-based stochastic method, to simulate ground motions over a wide range of magnitudes. Drawing on previous results for the modeling of recordings from the 2011 M-w 5.8 Mineral, Virginia, earthquake and using the 2001 M-w 7.6 Bhuj, India, earthquake as a tectonic analog for a large magnitude CEUS event, we are able to calibrate the two simulation methods over this magnitude range. Both models show a good fit to the Mineral and Bhuj observations from 0.1 to 10 Hz. Model parameters are then adjusted to obtain simulations for M-w 6.5, 7.0, and 7.6 events in the CEUS. Our simulations are compared with the 2014 U.S. Geological Survey weighted combination of existing ground-motion prediction equations in the CEUS. The physics-based simulations show comparable response spectral amplitudes and a fairly similar attenuation with distance. The site-based stochastic simulations suggest a slightly faster attenuation of the response spectral amplitudes with distance for larger magnitude events and, as a result, slightly lower amplitudes at distances greater than 200 km. Both models are plausible alternatives and, given the few available data points in the CEUS, can be used to represent the epistemic uncertainty in modeling of postulated CEUS large-magnitude events.