Wednesday, April 27, 2011

Earthquakes 101 - Understanding Magnitude

A moderate earthquake is defined as magnitude 5.0 to 5.9; strong is 6.0 to 6.9; major is 7.0 to 7.9; and a great earthquake registers 8.0 or higher on the Richter scale. Because the scale is logarithmic, there is a tenfold increase in the amplitude of the shockwaves with each higher whole number on the scale. Some studies have estimated that this tenfold increase in the amplitude of the shockwaves would require thirty-two times more energy. So a magnitude 9 would generate thirty-two times more energy than a magnitude 8.