Earthquakes are measured by special machines called seismometers. Scientists use the numbers from 1 to 10 to say how strong an earthquake is. This number system is called a scale, or a magnitude scale. Magnitude means how big or strong something is. Higher numbers mean stronger earthquakes.
The scale is a little bit tricky because for each number you go up in the scale, the strength of the earthquake is 10 times stronger. For example, a 5.0 earthquake is about 10 times stronger than a 4.0 earthquake, and 100 times stronger than a 3.0 earthquake.
Charles Richter created the Richter magnitude scale in 1935. Later, scientists started using the “moment magnitude scale” (MMS) instead. But the scales are about the same.
Here is a general idea of the scale:
|1.0-2.0||People do not feel these.|
|3.0||People can feel these, but they almost never cause damage.|
|4.0||Objects inside houses can move, causing noise. Things are rarely damaged.|
|5.0||Buildings that are not built well may be damaged. Light objects inside a house may be moved.|
|6.0||Medium power. May cause a lot of damage in a larger area.|
|7.0||Can damage things seriously over larger areas.|
|8.0-9.9||Massive (huge) damage is caused.|
|10.0+||There are no records of anything of this size.|