what are the similarities between the earthquakes?
To compare two earthquakes in terms of shaking, you subtract one magnitude from the other and raise 10 to that power: 10^(M1-M2). 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.