What is the principle underlying the determination of the strength of an earthquake?

An earthquake is a violent shaking of the earth’s surface. Several scales are used to measure the strength of an earthquake:

– Richter scale. The most common. To measure the magnitude of waves appearing during an earthquake, a seismograph is used. Usually, on this scale, the strength of an earthquake is from 1 to 8 points. Waves of 1 point are practically invisible to us and can be determined using other more sensitive devices. Waves of 8 points cause huge destruction of buildings, faults of the earth’s surface.

– Mercalli scale. On this scale, the strength of an earthquake can reach from 1 to 12 points.

The readings of these scales depend on the depth of the earthquake source.