California's three major fault lines may have had a century off from major earthquakes, but a new study shows that Southern California is teeming with tiny temblors.

The research appears in the journal Science.

Researchers applying a fine-grained analysis called "template matching" to seismic data in Southern California have found 2 million previously unknown earthquakes in the last decade — 10 times the number previously cataloged.

The tiny tremors that shiver the area 500 times a day fall between negative 2.0 and positive 1.7 magnitude, or roughly the vibration caused by construction or traffic.

They average three minutes apart, which is 10 times more frequent than previously thought.

The new data could help scientists better understand the foreshocks that precede major earthquakes and the development of earthquake swarms.