TSUNAMI EVACUATION BUILDINGS AS A RISK MANAGEMENT SOLUTION

The Pacific Northwest’s extreme disaster is a magnitude 9 earthquake on the Cascadia subduction zone, which would produce minutes of strong ground shaking, coastal subsidence, landslides, liquefaction, lateral spreads, and a near-field tsunami. The near-field tsunami will arrive in 15 to 30 minutes along the coast, exposing many low-lying coastal communities are inundation hazards.

To minimize extensive direct earthquake and tsunami damage, a number of strategically located, well-designed and constructed tsunami evacuation buildings (TEBs) are necessary. These TEBs need to meet an immediate occupancy performance level when subjected to long duration, large magnitude, subduction zone earthquakes rich in low frequency ground motions. In addition, TEBs need to withstand a variety of tsunami loads, including hydrodynamic stresses, debris impacts and scouring. Planning for routine functionality as well as community evacuation during low probability disasters will meet with many challenges, such as evacuation access for a physically disabled population and liability issues.

To enhance and expedite progress on the development of TEBs, we recommend a multidisciplinary comprehensive approach involving technical research, public awareness, and the eventual construction of a demonstration TEB at Cannon Beach, Oregon. The technical research would include a range of experiments at the O.H. Hinsdale Wave Research Facility at Oregon State University, such as inundation in urban waterfronts to determine efficacy of the constructed environment on tsunami height and flow velocity, and tsunami resistant buildings including deep foundations to determine wave loads, scouring and performance. Research would also include earthquake engineering and social science issues.