Since tsunami are long-wavelength waves, a long time can pass between crests or troughs. Any part of the wave can make landfall first. In 1755 in Lisbon, Portugal, a tsunami trough hit land first. A large offshore earthquake did a great deal of damage on land. People rushed out to the open space of the shore. Once there, they discovered that the water was flowing seaward fast and some of them went out to observe. What do you think happened next? The people on the open beach drowned when the crest of the wave came up the beach. Large tsunami in the Indian Ocean and more recently Japan have killed hundreds of thousands of people in recent years. The west coast is vulnerable to tsunami since it sits on the Pacific Ring of Fire. Scientists are trying to learn everything they can about predicting tsunamis before a massive one strikes a little closer to home. Although most places around the Indian Ocean did not have warning systems in 2005, there is a tsunami warning system in that region now. Tsunami warning systems have been placed in most locations where tsunami are possible. Click image to the left or use the URL below. URL:

tsunami as waves

Tsunami are deadly ocean waves from the sharp jolt of an undersea earthquake. Less frequently, these waves can be generated by other shocks to the sea, like a meteorite impact. Fortunately, few undersea earthquakes, and even fewer meteorite impacts, generate tsunami.

wave height

Tsunami waves have small wave heights relative to their long wavelengths, so they are usually unnoticed at sea. When traveling up a slope onto a shoreline, the wave is pushed upward. As with wind waves, the speed of the bottom of the wave is slowed by friction. This causes the wavelength to decrease and the wave to become unstable. These factors can create an enormous and deadly wave. Landslides, meteorite impacts, or any other jolt to ocean water may form a tsunami. Tsunami can travel at speeds of 800 kilometers per hour (500 miles per hour).

instructional diagrams

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tsunami is japanese for

a) tidal wave

b) large wave

-->  c) harbor wave

d) great wave

the 2004 indian ocean tsunami killed so many people because

a) it struck all around the indian ocean so many settlements were hit.

b) it was an enormous wave, generated by an enormous earthquake.

c) the people of the region did not expect a tsunami so there was no warning system.

-->  d) all of the above

a ship at sea will probably not know when a tsunami passes beneath it.

-->  a) true

b) false

a tsunami wave grows large

a) as soon as the wave is generated.

b) when it combines with large ocean waves.

-->  c) when the wave is pushed upward by the shore.

d) none of the above

if you are on a beach and the water rushes out to sea, you should

a) follow it to see what is happening.

-->  b) run in the other direction as fast as possible.

c) stay where you are to see what happens next.

d) relax and not worry about it.

tsunami have high wave heights and short wavelengths.

a) true

-->  b) false

why is the west coast of north america especially vulnerable to tsunami?

-->  a) a lot of earthquakes happen around the pacific ring of fire.

b) the islands of the pacific, like hawaii, have a lot of volcanic activity.

c) the ocean is so big that lots of meteorites can strike it.

d) with all that water, the waves can travel faster and grow higher.

tsunami can travel at speeds of

a) 80 kilometers per hour

-->  b) 800 kilometers per hour

c) 8 kilometers per hour

d) 8000 kilometers per hour

tsunami warnings have been placed where tsunamis are possible.

-->  a) true

b) false

you would be more likely to drown in a tsunami in a flat region than on a steep beach because the wave could travel farther inland and you couldnt outrun it.

-->  a) true

b) false

diagram questions

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