Where Do Tsunamis Occur?

By Teo Spengler

Tsunamis: Do you know what to do if one occurs?

Where Do Tsunamis Occur?

If you have ever driven to a low coastal area, you might have seen the sign "Tsunami Hazard Zone." Tsunamis are series of ocean waves caused by major movements in the ocean, such as earthquakes, landslides and volcanic activity. They can and do present mortal danger to people in certain coastal zones. If you are vacationing on the coast, it's important to know exactly what a tsunami is and what to do in case of a tsunami warning. Here are answers to some of the most pressing questions about tsunamis.

Q: What is a tsunami?

A: Tsunamis are among the most destructive natural disasters in the natural world. The word tsunami comes from the Japanese characters for harbor and wave. Tsunamis are most often caused caused by fairly shallow but powerful earthquakes of magnitude 7 or higher, generating a series of powerful waves. These waves inundate coastal areas, drowning people and damaging or destroying structures and houses.

Q: How dangerous are tsunamis?

A: In the past 250 years, over 420,000 people have been killed in tsunamis. In the same period, these waves have caused billions of dollars of property damage. Unlike ordinary waves that roll in, with the wave water turning in circles, tsunami waves do not roll. The water comes in straight, like a wall of water.

Q: How often do tsunamis occur?

A: Most of the losses of life and property damage have been caused by local tsunamis, when earthquakes occur close to populated shores. Local tsunamis happen about once a year.

Q: Where do tsunamis occur?

A: Tsunamis often occur in the Pacific. The heavy oceanic plates in this region slip under the light continental plates. Broken plates cause the seafloor to move up and down, a movement that transfers energy to the ocean.

Q: Can tsunamis be prevented or forecast?

A: Since humankind cannot control earthquakes, there is no way to prevent tsunamis. Advances have been made in forecasting tsunamis, thanks to a new type of real-time, deep-ocean tsunami detector and high-resolution inundation models. As of yet, however, there is no proof that these inundation forecast models will work for every tsunami. But experts estimate that they can prevent some loss of life associated with tsunamis.

Q: Is there an official warning system?

A: Many countries and the coastal states in the United States have tsunami warning systems set up. These systems take information from the tsunami-forecasting equipment and connect it with a communications system that broadcasts the tsunami warning over the radio and even on the beaches in affected areas.

Q: What should I do if I hear a warning?

If you hear a tsunami warning while you are on a beach or in a low-lying beach town, you should leave the area immediately. Head as fast as you can for higher ground. Although some warnings prove to be false alarms, lives have been lost when people ignore the warnings or head to the beach to take photos. You should also leave the beach for higher ground if you hear that a major earthquake has happened that might affect your area.

About the Author

Teo Spengler earned a J.D. from U.C. Berkeley's Boalt Hall. As an Assistant Attorney General in Juneau, she practiced before the Alaska Supreme Court and the U.S. Supreme Court before opening a plaintiff's personal injury practice in San Francisco. She holds both an M.A. and an M.F.A in creative writing and enjoys writing legal blogs and articles. Spengler splits her time between French Basque Country and California.