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Tsunamis are a series of large ocean waves generated by major earthquakes beneath the ocean floor or major landslides into the ocean. When the waves enter shallow water, they may rise to several feet or, in rare cases, tens of feet, striking the coast with devastating force. People on the beach or in low coastal areas need to be aware that a tsunami could arrive within minutes after a severe earthquake. The tsunami danger period can continue for many hours after a major earthquake. A tsunami can occur during any season of the year and at any time, day or night.
 
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.
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Take the appropriate steps to be prepared
  • 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.
  • Plan evacuation routes from your home, school, workplace and other places you could be where tsunamis present a risk. If possible, pick areas 100 feet (30 meters) above sea level or go as far as 2 miles (3 kilometers) inland, away from the coastline. If you cannot get this high or far, go as high or far as you can. Every foot inland or upward may make a difference. You should be able to reach your safe location on foot within 15 minutes.
  • Find out what the school evacuation plan is.Find out if the plan requires you to pick your children up from school or from another location. Telephone lines during a tsunami watch or warning may be overloaded, and routes to and from schools may be jammed.
  • Practice your evacuation routes. 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.
  • If you are a tourist, familiarize yourself with local tsunami evacuation protocols. You may be able to safely evacuate to the third floor and higher in reinforced concrete hotel structures.

If you are in a coastal area and feel an earthquake that lasts 20 seconds or longer:

  • Drop, cover and hold on. You should first protect yourself from the earthquake.
  • When the shaking stops, gather members of your household and move quickly to higher ground away from the coast. A tsunami may be coming within minutes.
  • Avoid downed power lines and stay away from buildings and bridges from which heavy objects might fall during an aftershock.
 
What to Do During a Tsunami Watch
  • Use a NOAA Weather Radio or tune to a Coast Guard emergency frequency station or a local radio or television station for updated emergency information.
  • Locate household members and review evacuation plans. Be ready to move quickly if a tsunami warning is issued.

What to Do During a Tsunami Warning
  • If you hear an official tsunami warning or detect signs of a tsunami, evacuate at once.
  • Take your emergency preparedness kit. Having supplies will make you more comfortable during the evacuation.
  • Take your pets with you. If it is not safe for you, it’s not safe for them.
  • Get to higher ground as far inland as possible. Watching a tsunami could put you in grave danger. If you can see the wave, you are too close to escape it.
What is the best source of information in a tsunami situation?

The International Tsunami Warning System monitors ocean waves after any Pacific earthquake with a magnitude greater than 6.5. If waves are detected, warnings are issued to local authorities who can order the evacuation of low-lying areas if necessary.
 
The National Oceanic and Atmospheric Administration (NOAA)’s National Weather Service operates two tsunami warning centers:
 
West Coast/Alaska Tsunami Warning Center (WC/ATWC), Palmer, Alaska. Serves Alaska, Washington, Oregon, California, the U.S. Atlantic and Gulf of Mexico coasts, Puerto Rico, the U.S. Virgin Islands and Canada.Pacific
 
Tsunami Warning Center (PTWC), Ewa Beach, Hawaii. Serves Hawaii and the U.S. Pacific territories, and as an international warning center for the Pacific and Indian oceans and the Caribbean Sea.


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