Measuring Earthquakes

Earthquakes can be measured several ways - by the magnitude of the earthquake wave as measured on a seismograph (that´s the Richter Scale, the one they talk about on TV) or by damage (the Mercalli Scale, which could vary from place to place).

The Richter Scale is logarithmic, which means that a quake of magnitude 5.0 causes a wave on a seismograph that is 10 times a magnitude 4.0 quake, and a 6.0 quake is 100 times the magnitude of a 4.0 quake. But it´s 30 times as much power. That means a 5.0 quake releases 30 times the energy of a 4.0 quake, and a 6.0 quake releases 900 times the energy of a 4.0 quake!