This publication presents the following information:
- General information on the tsunami hazard and its history;
- Guidance on determining the tsunami hazard, including the need for tsunami depth and velocity on a site-specific basis;
- Different options for vertical evacuation from tsunamis;
- Determination of tsunami and earthquake loads and structural design criteria necessary to address them; and
- Structural design concepts and other considerations.
This is the third edition of FEMA P-646, originally published in June 2008. In this third edition, revisions were made throughout the document, but particularly in the following areas:
- Expanded guidance on planning for vertical evacuation
- Additional guidance and commentary on structural design criteria contained in the new Chapter 6, “Tsunami Loads and Effects” of ASCE/SEI 7-16, Minimum Design Loads and Associated Criteria for Buildings and Other Structures (ASCE, 2016);
- Inclusion of guidance on using existing structures for vertical evacuation; and
- Operational guidance for tsunami vertical evacuation structures.
This third edition builds on the second edition, which included observations and lessons learned from the March 11, 2011 Tohoku tsunami; revised and enhanced the debris impact expression to remove over-conservatism in the prior edition; and updated reference documents to the most current versions.
This report is intended as a resource for state and local government officials, community planners, engineers, architects, building officials, emergency managers, tsunami planning activists, and building owners who are considering the construction and operation of tsunami-resistant structures that are intended to provide a safe haven for evacuees during short-term, high-risk tsunami events. It provides guidance on the planning, location, operation, design, and construction of structures that could be used as a refuge for vertical evacuation above rising waters associated with tsunami inundation. Much of the information contained in a report originally published as a companion to the first edition, FEMA P-646A, Vertical Evacuation from Tsunamis: A Guide for Community Officials (FEMA, 2009) has now been incorporated directly into this third edition.