Vertical Evacuation from Tsunamis

This publication was equally funded by the National Oceanic and Atmospheric Administration (NOAA), which leads the National Tsunami Hazard Mitigation Program (NTHMP) and by the Federal Emergency Management Agency (FEMA), which is responsible for the implementation portion of the National Earthquake Hazard Reduction Program (NEHRP). This project was originally undertaken to address the need for guidance on how to build a structure that would be capable of resisting the extreme forces of both a tsunami and an earthquake. This question was driven by the fact that there are many communities along our nation's west coast that are vulnerable to a tsunami triggered by an earthquake on the Cascadia subduction zone, which could potentially generate a tsunami of 20 feet in elevation or more within 20 minutes. Given their location, it would be impossible to evacuate these communities in time, which could result in a significant loss of life. This issue came into sharp relief with the December 26, 2004 Sumatra earthquake and Indian Ocean tsunami. While this event resulted in a tremendous loss of life, this would have been even worse had not many people been able to take shelter in multi-story reinforced concrete buildings. Without realizing it, these survivors were among the first to demonstrate the concept of vertical evacuation from a tsunami. Many coastal communities subject to tsunami located in other parts of the country also have the same issue. In these cases, the only feasible alternative is vertical evacuation, using specially designed, constructed and designated structures built to resist both tsunami and earthquake loads. The design of such structures was the focus of the earlier work on this project, which resulted in the FEMA publication, Guidelines for Design of Structures for Vertical Evacuation from Tsunamis (FEMA P646). This is a companion publication intended to present information on how vertical evacuation design guidance can be used and encouraged at the state and local level. It is meant to help state and local government officials and interested citizens by providing them with the information they would need to address the tsunami hazard in their community, to help determine if vertical evacuation is an option they should consider, and if so, how to fund, design and build such a refuge.