A Probabilistic Framework for Coseismic Tsunami Design-Video

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Video Summary

The presentation introduces a probabilistic method for assessing combined seismic and tsunami demands on port structures. Conventional design treats the hazards independently, but earthquakes can damage structures before tsunami waves arrive. The proposed approach extends standard seismic hazard analysis to estimate the joint annual exceedance rates of ground acceleration and tsunami height.<br /><br />The method was applied to the Friday Harbor Ferry Terminal in Washington, using Cascadia subduction-zone models. Results show that conditioning tsunami demand on seismic shaking—and vice versa—can substantially reduce design demands compared with assuming the independent maximum loads occur together. For a 2,500-year return period, the presenter reported reductions of about 76% in seismic demand and 62% in tsunami demand. Because reliable correlation models are not yet available, the analysis uses conservative assumptions.<br /><br />The presentation notes that codes require tsunami design for some facilities and jurisdictions, but current practice does not specify how many combined seismic–tsunami load pairs designers should consider.

Keywords

seismic tsunami hazard

port structures

joint annual exceedance

Friday Harbor Ferry Terminal

Cascadia subduction zone