A closer look at tsunamis

The chance of a major tsunami hitting the Cayman Islands is slim, but that is no reason not to understand them and know how best to survive one.

You are happily swimming at the beach and suddenly the water around you vanishes. It was sucked out to sea for some strange reason. You have never seen anything like this in your life. It’s difficult to comprehend, but you are standing in wet sand where there was an ocean just a minute ago. People around you are as bewildered by this strange phenomenon as you are. They yell for friends and family to come out and see all the stranded fish flopping around. A few grab cameras and start taking photos.

What do you do?

Run. You are about to be smashed by a tsunami, one of nature’s most bitter cruelties. As millions of people in 11 Asian and African countries tragically learned last month, tsunamis can devastate coastal communities and kill tens of thousands. They have done it throughout history and will continue to do so.

Many people may have died in Asia and Africa unnecessarily because they did not respond to warning signs and remained in the waves’ kill zone. The current death toll is more than 140,000 and expected to continue rising. This is one of the worst natural disasters of all time.

What are tsunamis? Tsunamis are a series of waves that are created when a huge amount of ocean water is moved suddenly. Usually this is achieved by powerful undersea earthquakes, but landslides, volcanic eruptions and even meteor strikes can cause tsunamis as well. For a demonstration, the next time you are in a bathtub, abruptly move your mostly-submerged body and then watch water begin crashing against the sides of the tub. This is what happens in the ocean. The sea floor moves suddenly and tons of water are jolted into high-speed action with potentially deadly consequences.

Tsunamis can be very wide, as much as 60 miles across, according to a National Geographic report. They can also arrive in intervals as long as an hour between waves so one should not assume the worst is over immediately after a wave hits.

Their speed and range is astonishing. The tsunamis that struck the Asian and African countries last week, for example, reportedly traveled at 500 mph in the open sea and was able to hit some coastal communities with lethal force after a 3,000 mile journey.

Tsunamis do not always strike coasts in the form of large breaking waves. Some tsunamis arrive only as a sudden rise in sea level. These are also extremely dangerous, however.

Many witnesses and survivors of a tsunami say it sounds like an approaching freight train.

Most of the world’s dangerous tsunamis occur in the Pacific today but they can happen anywhere. According to National Geographic, every coastline in the world is hit by a tsunami sooner or later. The Caribbean has been struck by 37 verified tsunamis over the last five centuries, killing nearly 10,000 people.

What to do. Experts recommend immediately moving away from beaches if you feel a strong earthquake or hear that a strong earthquake has just occurred. If the earthquake is strong enough and far enough away, it may take hours for a tsunami to arrive.

Lori Dengler, professor of geology at Humboldt State University and director of the Earthquake Education Center, is blunt about the proper thing to do. ‘If you feel an earthquake, get off the beach and find out about it later!’ (quoted in an Environmental News Network report)

In countries with rivers and streams, one should stay away from them because they might also pose a danger as tsunamis can travel upriver. Anyone in a boat who hears a report of a tsunami threat should not approach land. Finally, don’t get caught up in the excitement of watching an approaching wave. Get away from the beach as fast as you can. Head for high ground if possible.

Earthquakes and tsunamis, as terrible as they can be for us, are normal events in geological terms. The United States Geological Survey estimates several million earthquakes occur each year with some 20,000 of them per year detected and logged.

There is no factual support behind claims that earthquakes or tsunamis are more frequent or more powerful now than in the past.

Sources: National Geographic; United Sates Geological Survey; NOAA; Associated Press.

*Scientists do not call tsunamis ‘tidal waves’ because they are not caused by tides. Tsunami is the chosen name.

It’s a Japanese word that means ‘harbor wave’.

*The 9.0 earthquake of December 26 that caused the deadly tsunamis released an amount energy equivalent to 475,000 kilotons (475 megatons) of TNT, or amount equal to 23,000 Hiroshima bombs.

*The following are useful websites to learn more about tsunamis and tsunami safety: