NGA-Subduction Ground Motion Models for Interface and Intraslab Events, with a focus on Cascadia Regionalization
Grace Parker, USGS
Wednesday, May 15, 2019 at 10:30 AM
- Building 3, Rambo Auditorium
The Next Generation Attenuation Subduction (NGA-Sub) project is a multi-year, multidisciplinary project with the goal of developing an earthquake ground motion database and ground motion models for global subduction zone earthquakes, including those in Japan, Taiwan, Cascadia, Alaska, New Zealand, Mexico, and Central and South America. A combination of data inspection, regression techniques, ground motion simulations, and geometrical constraints are used to develop regionalized models for shaking intensity from interface and intraslab events. Complex path effects are observed in the data, including differences in distance-scaling between interface and intraslab events, forearc and back-arc effects, and regional variations. Our approach to model development was to first constrain a path term capturing these effects, then to subsequently investigate magnitude scaling, source depth scaling, and site effects. Regionalized terms of the ground-motion model include the model amplitude, anelastic attenuation, magnitude-scaling breakpoint, VS30-scaling, and sediment depth terms. This seminar will contain an overview of model development, and highlights the event-type and regional variations across the models, with a particular focus on Cascadia.