Have you ever heard the word tsunami? A tsunami is an ocean wave that can be a very large and dangerous and can flood coastal areas, causing incredible devastation. Most tsunamis are caused by the movement of the ocean floor during a large earthquake. Recent tsunamis in Indonesia, Samoa, Chile and Japan have shown the incredible power of these waves and the tragic effects they inflict on people and property. Those four tsunamis wiped out entire villages and resulted in the drowning deaths of thousands of people. As devastating as these waves are, you can protect yourself and others by knowing what to do if a tsunami occurs.
What can you do to protect yourself? First, if you are near the ocean and feel an earthquake that lasts for 20 seconds or longer, move away from the water to higher ground. Second, if you are at the beach and see the water draw out, exposing the sea floor, get away from the beach and go quickly to higher ground. If a tsunami warning is issued, follow the instructions from police or fire fighters. As a general rule though, you need to move inland to higher ground or to the fourth floor (or higher) of a strong building. Because tsunamis can last for up to two days, always make sure it is safe before returning to the shore.
What makes these waves so dangerous? It has to do with the distance between crests or peaks of the wave. Picture yourself on a beach. As you sit there, you will see a new wave come in about every three to ten seconds. If you sit there long enough, you will see the tide go in and out about every 12 hours. If you’re sitting there when a tsunami comes in (and hopefully you won’t be), the wave will come in and go out about every fifteen minutes. Because of the time between waves, tsunamis do not break and lose their energy at the shore, but rather, the water rushes over the land, creating strong currents that produce great damage.
How do we know when a tsunami is coming? Thankfully, giant tsunamis are rare. When they do occur, they normally follow large earthquakes. Scientists at the National Weather Service’s Tsunami Warning Centers work around the clock to monitor the earth so that tsunami warnings can be issued. These scientists use special ocean sensors to help detect tsunamis. These sensors, along with seismometers (which measure earthquakes), provide tsunami forecasters with the information they need. Even though forecasters can issue tsunami warnings within five minutes after an earthquake, sometimes the warning is too late for those near the coast. That’s why it’s important to know what to do.
While most tsunamis are caused by earthquakes, tsunamis can also be caused by land sliding into the ocean, underwater volcanic eruptions and even meteorites hitting the ocean. Scientists are still exploring new ways to help predict and warn people of tsunamis. But even with future improvements, you need to remember to move away from the water to higher ground if you see any signs of a tsunami.
Paul Whitmore is the Director of the National Tsunami Warning Center in Palmer, Alaska.
