Teaching kids about quakes, tsunamis
My 13-year-old daughter was riveted Saturday by the terrible news of the strong Chilean earthquake and tsunami warnings (which she learned about on Twitter). She wanted to know if it was connected to the earthquake hours earlier off the coast of Japan, and with the one in Haiti last month.
We talked about the theory of plate tectonics that she learned about (and I got a refresher on) when she was in sixth grade. I was glad she had retained an understanding of it, though exactly how tsunamis move across the ocean was less clear.
The Chilean earthquake was far more powerful than the one in Haiti that killed an estimated 200,000 or more in January. Saturday's quake and its aftermath are going to be in the news for some time, and if you didn’t teach your kids about earthquakes when Port-au-Prince was struck, now is a good time, especially with the added potential for disaster from tsunamis.
Here are some sites that can help:
And the Federal Emergency Management Agency, or FEMA has one on tsunamis here.
Here is some information on plate tectonics, the theory that continents, mountains, volcanoes and earthquakes are created when vast geological plates in the Earth's outer layer move and collide.
Tsunami comes from the Japanese word for harbor wave. They are not huge waves that ride on top of the surface of the ocean, (as I mistakenly used to think when I was a kid and called them tidal waves).
They are, rather, huge waves created by some undersea disturbance--an earthquake or volcanic eruption--that travel in all directions from the point of that disturbance. The principle is the same as the ripples you see if you throw a rock into water.
But these waves can travel in the open water as fast as 450 miles per hour. As they approach the shoreline, where the waters are much less deep, the ocean bottom pushes them up to a great height, sometimes as high as 100 feet.
Are the recent earthquakes connected, even if they aren’t on the same geographical plates? According to National Geographic, there is a theory that says it is possible. Read about it here.
The state at the highest risk of a tsunami is Hawaii, where people are being evacuated from coastal regions today because of the Chilean earthquake. Hawaii is struck about once a year, with a particularly damaging one every seven years.
According to FEMA, Alaska is also at high risk, and the states of California, Oregon and Washington are hit with a damaging tsunami about every 18 years.
The Chilean earthquake was rated as an 8.8 on the Richter scale, which makes it extremely powerful, more powerful than the Haiti earthquake. To understand how earthquakes are rated, go to this Scholastic website. There you will learn about how the measuring scale for earthquakes works. Today’s was 8.8, and the one in Haiti was 7.0 Here are some comparisons, according to Scholastic:
9.0 — Causes complete devastation and large-scale loss of life.
8.0 — Very few buildings stay up. Bridges fall down. Underground pipes burst. Railroad rails bend. Large rocks move. Smaller objects are tossed into the air. Some objects are swallowed up by the earth.
7.0 — It is hard to keep your balance. The ground cracks. Roads shake. Weak buildings fall down. Other buildings are badly damaged.
6.0 — Pictures can fall off walls. Furniture moves. In some buildings, walls may crack.
5.0 — If you are in a car, it may rock. Glasses and dishes may rattle. Windows may break.
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Posted by: sideswiththekids | March 3, 2010 8:21 AM | Report abuse
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