How earthquakes are measured

Updated 11:16 AM EDT, Tue April 28, 2015
(CNN) —  

Earthquakes are measured using seismographs, which monitor the seismic waves that travel through the Earth after an earthquake strikes.

Scientists used the Richter Scale for many years but now largely follow the “moment magnitude scale,” which the U.S. Geological Survey says is a more accurate measure of size.

Here are the magnitude classes:

Microearthquake:

– Magnitude: Less than 3.0

– Damage: Little to none

Minor earthquake:

– Magnitude: 3.0 - 3.9

– Damage: Little to none

Light earthquake:

– Magnitude: 4.0 - 4.9

– Damage: Moderate

Moderate earthquake:

– Magnitude: 5.0 - 5.9

– Damage: Considerable

Strong earthquake:

– Magnitude: 6.0 - 6.9

– Damage: Severe

Major earthquake:

– Magnitude: 7.0 - 7.9

– Damage: Widespread, heavy

Great earthquake:

– Magnitude: 8.0 and up

– Damage: Tremendous