| Tsunami Fact Sheet | ||||||
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Tsunamis are ocean waves produced by earthquakes or underwater landslides. The word is Japanese and means "harbor wave," because of the devastating effects these waves have had on low-lying Japanese coastal communities.
Tsunamis are often incorrectly referred to as tidal waves, but a tsunami is actually a series of waves that can travel at speeds averaging 450 (and up to 600) miles per hour in the open ocean. In the open ocean, tsunamis would not be felt by ships because the wavelength would be hundreds of miles long, with amplitude of only a few feet. This would also make them unnoticeable from the air. As the waves approach the coast, their speed decreases and their amplitude increases. Unusual wave heights have been known to be over 100 feet high. However, waves that are 10 to 20 feet high can be very destructive and cause many deaths or injuries.
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. Most deaths caused by a tsunami are because of drowning.
Two plate systems in the Atlantic Ocean are of concern to officials along the East Coast: one off the coast of Europe and Africa and the other north of the island of Puerto Rico. Both have the potential to cause Tsunamis that could affect our coastline.
In 1886, an earthquake struck the downtown Charleston area. It is reported that this earthquake caused minor tsunamis along the East Coast of the United States.
1. The best protection following a tsunami warning is to evacuate from coastal areas or move to a third- floor level.
2. A tsunami is a series of waves. Do not assume that one wave means that the danger is over. The next wave may be larger than the first one. Stay out of the area.
3. The greatest danger exists to those in areas at an elevation of less than 20 feet. Water being pushed inland by the tsunami will be bring massive amounts of debris as it pushes inland, including vehicles and small buildings.
Find out if your home is in a danger area. Know the height of your street above sea level and the distance of your street from the coast. Evacuation orders may be based on these numbers.
Be familiar with the tsunami warning signs. Because tsunamis can be caused by an underwater disturbance or an earthquake, people living along the coast should consider an earthquake or a sizable ground rumbling as a warning signal. A noticeable rapid rise or fall in coastal waters is also a sign that a tsunami is approaching.
Make sure all family members know how to respond to a tsunami, especially if you live on a barrier island or near a coastal water way.
Locate safe places outdoors
Teach children how and when to call 9-1-1 and which radio station to tune to for emergency information.
Have disaster supplies on hand
Develop an emergency communication plan
Ask an out-of-state relative or friend to serve as the "family contact." After a disaster, it’s often easier to call long distance. Make sure everyone in the family knows the name, address and phone number of the contact person.
Mitigation
Listen to a radio or television to get the latest emergency information, and be ready to evacuate if asked to do so. If you hear an official tsunami warning or detect signs of a tsunami, evacuate at once. Climb to higher ground. A tsunami warning is issued when authorities are certain that a tsunami threat exists.
Stay away from the beach. Never go down to the beach to watch a tsunami come in. If you can see the wave, you are too close to escape it.
Return home only after authorities advise it is safe to do so. A tsunami is a series of waves. Do not assume that one wave means that the danger is over. The next wave may be larger than the first one. Stay out of the area.
Stay tuned to a battery-operated radio for the latest emergency information.
Help injured or trapped persons.
Give first aid where appropriate. Do not move seriously injured persons unless they are in immediate danger of further injury. Call for help.
Remember to help your neighbors who may require special assistance — infants, elderly people, and people with disabilities.
Stay out of damaged buildings. Return home only when authorities say it is safe.
Enter home with caution. Use a flashlight when entering damaged buildings. Check for electrical shorts and live wires. Do not use any appliances or lights until an electrician has checked the electrical system.
Open windows and doors to help dry the building.
Shovel mud while it is still moist to give walls and floors an opportunity to dry.
Check food supplies and test drinking water. Fresh food that has come in contact with flood waters may be contaminated and should be thrown out. Have tap water tested by the local health department.
How the Public Can Help After a Disaster
· Financial aid is an immediate need of disaster victims. Financial contributions should be made through a recognized voluntary organization to help ensure that contributions are put to their intended use.
· Before donating food or clothing, wait for instructions from local officials. Immediately after a disaster, relief workers usually don’t have the time or facilities to setup distribution channels, and too often these items go to waste.
· Volunteers should go through a recognized voluntary agency such as the American Red Cross or Salvation Army. They know what is needed and are prepared to deal with the need. Local emergency services officials also coordinate volunteer efforts for helping in disasters.
· Organizations and community groups wishing to donate items should first contact local officials, the American Red Cross, or Salvation Army to find out what is needed and where to send it. Be prepared to deliver the items to one place, tell officials when you’ll be there, and provide for transportation, driver, and unloading.
· In 1964, an Alaskan earthquake generated a tsunami with waves between 10 and 20 feet high along parts of the California, Oregon, and Washington coasts. This tsunami caused more than $84 million in damage in Alaska and 123 fatalities in Alaska, Oregon, and California.
· Although tsunamis are rare along the Atlantic coastline, a severe earthquake on November 18, 1929, in the Grand Banks of Newfoundland generated a tsunami that caused considerable damage and loss of life at Placentia Bay, Newfoundland.
· In 1946, a tsunami with waves of 20 to 32 feet crashed into Hilo, Hawaii, flooding the downtown area and killing 159 people.
· The Tsunami Warning Centers in Honolulu, Hawaii, and Palme, Alaska, monitor disturbances that trigger tsunamis. When a tsunami is recorded, it is tracked and a tsunami warning is issued to the threatened area.
· Most deaths during a tsunami are a result of drowning. Associated risks include flooding, polluted water supplies, and damaged gas lines.
· Since 1945, more people have been killed as a result of tsunamis than as a direct result of an earthquake’s ground shaking.
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