How many aftershocks can be expected for each 1 decrease in earthquake magnitude?

The relationship between the magnitude of an earthquake and the number of aftershocks is rooted in seismological principles. For every unit that the magnitude of an earthquake decreases, it is generally observed that the number of aftershocks increases significantly, roughly by a factor of ten. This occurs because smaller earthquakes, which are less forceful, tend to be more frequent than larger ones.

When a major earthquake occurs, it creates a significant amount of stress along fault lines and in the surrounding geological structures. Aftershocks are the result of this stress being released as the earth continues to adjust in response to the initial quake. A decrease in magnitude means that a smaller initial earthquake produces more aftershocks. The empirical rule that suggests a tenfold increase in aftershocks with each unit decrease is a helpful guideline for predicting aftershock activity following seismic events.