Comparing Liquefaction Hazard Assessment Methods for Fuel Storage Facilities in Portland’s CEI Hub

The state of Oregon faces significant seismic risk from the Cascadia Subduction Zone (CSZ). An area of particular concern is Oregon’s Critical Energy Infrastructure (CEI) Hub, which contains over 90% of the state’s liquid fuel supply. Many CEI Hub facilities were built before state seismic codes addressed CSZ hazards and are located on liquefaction-susceptible soils. The Oregon Department of Environmental Quality’s Fuel Tank Seismic Stability (FTSS) program requires facilities to complete geotechnical studies, seismic vulnerability assessments, and risk mitigation implementation plans to address potential earthquake impacts. This paper provides an overview of the FTSS-mandated geotechnical seismic assessments for CEI Hub facilities, highlighting trends in methodology and variability in estimates of liquefaction and resulting displacements. Synthesis of these assessments provides an understanding of current practices for seismic vulnerability assessments in the Pacific Northwest.