Measuring an earthquake's intensity

Part of Hall of Planet Earth.

Measuring an Earthquake's Intensity AMNH/R.Mickens

How do seismologists compare the relative intensity and effects of earthquakes? The most familiar way is through the Richter scale, which measures the amount of ground motion. The scale is calibrated logarithmically, meaning that a 5 is ten times greater than a 4. Measured in terms of actual energy release, each step on the Richter scale represents 33 times more energy.