What causes a tsunami
A tsunami is a natural disaster that is most often caused by earthquakes beneath the sea floor. As deep sea waves created by the quake approach land, the shallower waters leave less room for the waves' energy to disperse. As a result, the waters rise, sometimes as waves as high as 100 feet, but more often as a powerful, fast-moving flood with strong currents.
Tsunamis can result from local or distant events. Local event tsunamis are likely to be very fast moving. Tsunamis are extremely dangerous for coastal areas.
Where do tsunamis occur
According to USGS.gov, tsunami events in the United States are relatively rare compared to the rest of the world. Even so, many U.S. coastal communities are at risk and recent disasters elsewhere in the world have demonstrated how destructive they can be.
The extraordinary destruction and loss of life caused has led to a new focus on tsunami safety for coastal areas throughout the United States. If you live along the Pacific, Atlantic, Gulf or Caribbean coasts, the tips below will help you learn more about tsunami risks and prepare your family to act quickly should a tsunami occur.
Before a tsunami
Tsunamis can happen very quickly, so proper planning now can save valuable time later. Here are a few tips.
- Create a plan. Help ensure your family's safety by developing a disaster preparedness plan that includes a disaster survival kit and an emergency evacuation plan. Tsunami evacuation plans should identify shelters and/or safe areas higher than 100 feet above sea level or up to two miles inland.
- Move to higher ground. If you are near a shoreline and feel a strong earthquake, evacuate to higher ground immediately. Other immediate warning signs include water pulling away from the shore and a loud ocean roar.
- Listen to advisories. The National Weather Service provides a Tsunami Warning System that warns of advisories and watches. A tsunami watch means that a tsunami has not yet been verified, but an earthquake or other event has made one possible. When a tsunami watch is in effect, use a battery-powered radio to keep up with the latest information.
- Evacuate when a warning is given. A tsunami warning means that a tsunami is on its way. Evacuate immediately to higher ground or inland areas. Do not go to coastal areas to watch for the tsunami, regardless of their elevation. If it is too late to evacuate, go to an upper level of a sturdy building or the highest ground you can access as soon as possible.
After a tsunami
Knowing how to deal with the aftermath of a tsunami is important. Additional severe activity may follow initial quakes and early waves, so remain at a higher elevation until the tsunami threat has completely passed. Local officials will issue an "all clear" advisory when appropriate.
Once the "all clear" advisory has been given, use caution or seek professional help when returning to your home. Upon returning, you should:
- Inspect damage. Make note of any visible damage carefully. Be mindful and careful of all visible and potential dangers including live wires, electrical shorts and gas or sewage leaks.
- Check your water supplies. Use your emergency water or boil tap water before drinking until you are told the water supply is safe.
- Check food supplies. Food that came in contact with floodwaters may be contaminated and should be discarded.
Ready.gov provides additional information on pre-planning and preparing for natural disasters.