Question

An earthquake of M8 causes the amplitude of ground motion to be _____ times larger than a M7 earthquake and _____ times larger than a M6 earthquake.

Answer 1

Answer: 10, 100

Explanation:

Magnitudes are based on a logarithmic scale (base 10). For each whole number you go up, the amplitude of the ground motion recorded by a seismograph goes up ten times. Using this scale, a magnitude 5 earthquake would result in ten times the level of ground shaking as a magnitude 4 earthquake (and 32 times as much energy would be released).

1 unit increase corresponds to 10 fold increase in magnitude.