Earthquake scenario selection for portfolio holders in CEUS: A case study with Oklahoma DOT

Portfolio managers of spatially distributed assets in the central and eastern United States (CEUS) and other low- to moderate seismic hazard regions require scenario-based seismic risk assessment for the purpose of emergency management and planning. Uncertainties regarding the long-term seismicity of the region, unknown faults, and limited historical records complicate the selection of an earthquake scenario. Through a case study with the Oklahoma Department of Transportation (ODOT) and their  portfolio of bridges, we look at one such exercise, which consists of two scenario earthquakes: one scenario earthquake selected from the U.S. Geological Survey Building Seismic Safety Commission (BSSC) scenario catalog, a magnitude (M) 7.2 event on the Meers fault, and a second aftershock selected by the consequence-driven earthquake scenario selection (Co-DESS) method. The latter is driven by ODOT’s desired service actions to be included during the earthquake drill; in this case, we identify an earthquake that is likely to trigger inspections for bridges across multiple districts, thereby testing not only inspection protocols but also coordination efforts between district groups. We find that the Co-DESS selected event is smaller in magnitude and offers different geographical options than selection through conventional selection methods, while still meeting necessary consequences for an effective earthquake exercise.