Several areas of the United States are subject to tsunamis, and the coast north of San Francisco through the Canadian border has a history of catastrophic tsunamis. This report from FEMA details the tsunami risk in the United States:
Those who saw the damage from the Hurricane Katrina storm surge have noted that it looks very much like the tsunami damage. While a hurricane surge does not have the initial force of a fast moving tsunami, the wave action during the long period of inundation leads to very similar damage. It is likely that the New Orleans levees will be no more effective than the tsunami walls when the next great storm comes to the Louisiana Coast. As the Japanese learned, it is failing to work with realistic estimates of wave heights, not construction, that ultimately determines the usefulness of flood walls.