Earthquake Magnitude Scale Magnitude Earthquake Effects Estimated Number Each Year 2.5 or less Usually not felt, but can be recorded by seismograph. Millions 2.5 to 5.4 Often felt, but only causes ...

There are a number of ways to measure the magnitude of an earthquake. Most scales are based on the amplitude of seismic waves recorded on seismometers. These scales account for the distance between ...

The magnitude of an earthquake is expressed by the Richter scale. An earthquake of magnitude 2 is the smallest quake that is normally felt by people. Earthquakes are commonly considered major if ...