Since 1946, six tsunamis have killed more than 350 people and damaged a half billion dollars of property in Hawaii, Alaska, and the West Coast. Tsunamis are most often generated by earthquake-induced movement of the ocean floor. Landslides, volcanic eruptions, and even meteorites can also generate a tsunami. If a major earthquake is felt, a tsunami could reach the beach in a few minutes, even before a warning is issued. Areas at greatest risk are less than 25 feet above sea level and within one mile of the shoreline.
If you are in a tsunami risk area, learn how to protect yourself, your family, and your property. Be familiar with the tsunami warning signs. A strong earthquake lasting 20 seconds or more near the coast may generate a tsunami. A noticeable rapid rise or fall in coastal waters is also a sign that a tsunami is approaching.
The West Coast/Alaska Tsunami Warning Center (WC/ATWC) and The Pacific Tsunami Warning Center (PTWC) may issue the following bulletins:
- WARNING: A tsunami was or may have been generated, which could cause damage; therefore, people in the warned area are strongly advised to evacuate.
- WATCH: A tsunami was or may have been generated, but is at least two hours travel time to the area in watch status. Local officials should prepare for possible evacuation if their area is upgraded to a warning.
- ADVISORY: An earthquake has occurred in the Pacific basin, which might generate a tsunami. WC/ATWC and PTWC will issue hourly bulletins advising of the situation.
- INFORMATION: A message with information about an earthquake that is not expected to generate a tsunami. Usually only one bulletin is issued.
Plan for a Tsunami
Tsunami-specific planning should include the following:
- Learn about tsunami risk in your community. Contact your local emergency management office or American Red Cross chapter. Find out if your home, school, workplace or other frequently visited locations are in tsunami hazard areas. Know the height of your street above sea level and the distance of your street from the coast or other high-risk waters. Evacuation orders may be based on these numbers.
- If you are visiting an area at risk from tsunamis, check with the hotel, motel, or campground operators for tsunami evacuation information and how you would be warned. It is important to know designated escape routes before a warning is issued.
If you are at risk from tsunamis, do the following:
- Develop a Family Disaster Plan. Please see the “Family Disaster Plan” section for general family planning information. Tsunami-specific planning should include the following:
- Discuss tsunami with your family. Everyone should know what to do in case all family members are not together. Discussing tsunamis ahead of time will help reduce fear and anxiety, and let everyone know how to respond. Review flood safety and preparedness measures with your family.
- Plan an evacuation route from your home, school, workplace, or any other place you’ll be where tsunamis present a risk. If possible, pick an area 100 feet above sea level or go up to two miles inland, away from the coastline. If you can’t get this high or far, go as high as you can. Every foot inland or upwards may make a difference. You should be able to reach your safe location on foot within 15 minutes. After a disaster, roads may become impassable or blocked. Be prepared to evacuate by foot if necessary. Footpaths normally lead uphill and inland, while many roads parallel coastlines. Follow posted tsunami evacuation routes; these will lead to safety. Local emergency management officials can help advise you as to the best route to safety and likely shelter locations.
- Practice your evacuation route. Familiarity may save your life. Be able to follow your escape route at night and during inclement weather. Practicing your plan makes the appropriate response more of a reaction, requiring less thinking during an actual emergency situation.
For more information regarding Tsunami preparedness, visit the following:
- Pacific tsunami warning system
- National Oceanic and Atmospheric Administration
- West Coast and Alaska Tsunami Warning System
- For kids: Tsunami Warning” – and online children’s book that illustrates the danger of a tsunami
