Thursday, August 16, 2007

When the earth moves

Scientists no longer measure the energy of an earthquake by the Richter scale. Today they say a quake is of a certain magnitude. When you go from one magnitude to the next, say from 4 to 5, the earthquake energy is 32 times greater.

A magnitude 7.9 earthquake struck off the coast of central Peru last night. Its energy was equivalent to that released by the 1980 Mount St. Helens eruption, and slightly less than the world’s largest nuclear test, about 1,000 times stronger than Hiroshima.

As if it didn’t have enough problems with an approaching hurricane, the island of Hawaii was hit Monday with a magnitude 5.3 earthquake.

On Sunday, a 5.1 magnitude earthquake shook central Spain.

And last Thursday a 7.5 magnitude quake hit the Indonesian island of Java.

But John Bellini of the USGS says that 7.5 magnitude earthquakes happen 18 times a year, so it’s not unusual for two occur in one week: it’s actually quite common.
In fact a million earthquakes occur each year, three thousand a day. Most are magnitude 2 and not even felt by people.

Earthquake myths abound. Here’s the boring truth: No animal reliably senses an impending earthquake. Earthquakes do not occur in any particular type of weather or time of day. Despite what you might’ve seen in the movies, the ground will not open and swallow people. California will not fall into the sea. And there is no inconvenient truth for earthquakes: the rate at which they occur has remained constant despite all of man’s earth moving.

Of course, musicians know earthquakes too:

Carole King: The Earth moves under my feet; and
Jerry Lee Lewis: There’s a whole lotta shakin’ goin’ on

It must be because they still use the Richter scale.

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