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FEMA Media Library

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Guidelines for Design of Structures for Vertical Evacuation from Tsunamis (FEMA P 646)

Vertical evacuation is a programmatic issue central to the National Tsunami Hazard Mitigation Program, driven by the fact that there are coastal communities along the West Coast of the United States that are vulnerable to tsunamis that could be generated within minutes of an earthquake on the Cascadia Subduction Zone. Vertical evacuation structures provide a means to create areas of refuge for communities in which evacuation out of the inundation zone is not feasible. This guidance document includes the following information to assist in the planning and design of tsunami vertical evacuation structures: general information on the tsunami hazard and its history; guidance on determining the tsunami hazard, including tsunami depth and velocity; different options for tsunami vertical evacuation structures; guidance on siting, spacing, sizing, and elevation considerations; determining tsunami and earthquake loads and related structural design criteria; and structural design concepts and other considerations.