Yet again, this myth continues to perpetuate - lots of little ones will NOT prevent a large temblor.

The less than 50% rule from THIS source:

[link to articles.washingtonpost.com]

3. Small earthquakes are helpful because they release pressure and prevent larger ones.

The earthquake magnitude scale, introduced by Charles Richter in 1935, is logarithmic, which means that progressively bigger quakes are a lot bigger than smaller quakes. For each unit increase in magnitude (i.e., going from 5.5 to 6.5), the energy released rises by a factor of about 30 — meaning that a two-unit increase translates into aquake that is nearly 1,000 times as severe. If enough stress has built up on a fault to generate a magnitude-7.0 earthquake, say, it would thus take about 1000 earthquakes with a magnitude of 5.0 to release the equivalent energy. The Earth doesn’t work that way.

In any given area, the numbers of tremors of different magnitudes almost always follow a simple mathematical progression, with about 10 magnitude-6.0 quakes and about 100 magnitude-5.0 quakes for every single magnitude-7.0 quake. Thus, if there is significant strain energy to be released, it must be released in large earthquakes.