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What Are Tsunamis?

Please visit the National Oceanic and Atmospheric Administration (NOAA) website to learn about Tsunamis.

NOAA has primary responsibility for providing tsunami warnings to the Nation, and a leadership role in tsunami observations and research. Tsunami messages are issued by NOAA’s Tsunami Warning Centers.

Awareness Information

The Pacific Tsunami Warning Center (PTWC) is responsible for providing warnings to international authorities, Hawaii, and U. S. territories within the Pacific basin. All tsunamis are potentially dangerous, even though they may not damage every coastline they strike.

Be familiar with the tsunami warning signs. A strong earthquake 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.

Tsunamis most frequently come onshore as a rapidly rising turbulent surge of water choked with debris. They are not V-shaped or rolling waves, and are not “surfable.”

Tsunamis may be locally generated or from a distant source. On March 11, 2011, a magnitude 9.0 earthquake struck off Japan’s northeastern shore – the most powerful earthquake ever recorded to have hit Japan – generating enormous tsunami waves that spread across miles of shoreline. The March 11 earthquake took nearly 16,000 lives.

Plan for a Tsunami

Tsunami-specific planning should include the following:

  • Learn about tsunami risk in your community. Contact your local city office. 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.
  • 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.
  • 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.

What to Do if You Feel a Strong Coastal Earthquake

If you feel a strong earthquake when you are on the coast:

  • Drop, cover, and hold on. You should first protect yourself from the earthquake.
  • When the shaking stops, gather your family members and evacuate quickly.
  • Leave everything else behind. A tsunami may be coming within minutes. Move quickly to higher ground away from the coast.
  • Be careful to avoid downed power lines and stay away from buildings and bridges from which heavy objects might fall during an aftershock.
  • Return home only after local officials tell you it is safe. A tsunami is a series of waves that may continue for hours. Do not assume that after one wave the danger is over. The next wave may be larger than the first one.
  • Monitor warnings and advisories issued by the Japan Meteological Agency’s website.