A tsunami is a series of water waves that send surges of water, which sometimes reach over 100 feet onto land and can cause widespread destruction. Tsunami is a Japanese word with the English translation “harbour wave”.

Most tsunamis, about 80 percent, take place within the Pacific Ocean, a geologically active area where volcanoes and earthquakes are common.

The formation of a Tsunami

Tsunamis can occur as a result of earthquakes, volcanic eruptions, landslides and other disturbances above or below.
When these events occur under the water, huge amounts of energy are released as a result of quick upward bottom movement.  For example, if a volcanic eruption occurs, the ocean floor may very quickly move upward several hundred feet.  When this happens, huge volumes of ocean water are pushed upward and a wave is formed.  A large earthquake can lift thousands of square kilometers of sea floor which will cause the formation of huge waves.

Tsunamis arise from the sudden displacement of gigantic water masses due to earthquakes on the sea bed, volcanic eruption above and under water, landslides or meteorite impacts. About 86 % of all Tsunamis result from so-called seaquakes.

Know how to prepare for a Tsunami

  • Find out if your home is in a vulnerable area. If you live in a low-lying area identify the quickest way to get to high ground.
  • Know the natural tsunami warning signs such as a strong earthquake or the sea pulling back from the coastline.
  • Discuss tsunamis with your family and friends. Everyone needs to know what to do in case everyone is not together.
  • Emergency supplies such as canned foods, drinking water, medication, flashlights, battery-powered radios and First Aid kits should be readily available.
  • Emergency equipment should also be on hand and working properly.

During a Tsunami

  • When fleeing a tsunami caused by a nearby earthquake, roads may be blocked or broken so be careful.
  • Tsunamis may occur without the initial pulling back of the sea and you might see a massive wall of water approaching land. If you can see the wave you are already too close to outrun it.
  • If you are unable to move to higher ground, go to an upper floor (at least the 3rd storey) or roof of a strong building. As a last resort, climb a strong tree if trapped on low ground.
  • If swept up by a tsunami, look for something to use as a raft.
  • A tsunami may last for hours so expect many waves.

After a Tsunami

  • Check for injuries and damage to property.
  • Stay tuned to a radio or television to know the latest emergency information.
  • Help injured or trapped people and call for help if necessary.
  • Check food supply and test drinking water. Fresh food that has come in contact with flood water may be contaminated and should be discarded.

Tsunamis that have affected Antigua and Barbuda

  • April 6 1690 – Earthquake near Antigua and Nevis believed to have triggered landslides into the sea which generated tsunami waves. These were observed in Antigua, Nevis and St. Thomas.
  • The 1755 Great Lisbon earthquake in Portugal, which had a magnitude of between 8.5 and 9.0, caused tsunamis throughout the Caribbean.