Question: what is the difference in earthquake magnitude?
Answer: The magnitude scale is logarithmic. That just means that if you add 1 to an earthquake's magnitude, you multiply the shaking by 10. ... For example, if the magnitude of one quake is 6 and another is 4, than the difference in magnitudes is 2, so the stronger earthquake shakes 10^2 or 100 times as hard as the milder one.