A magnitude-4.0 earthquake shook part of the San Bernardino County early Monday morning.
The tremor was reported by the United States Geological Survey at 3:26 p.m.
Two minor earthquakes rattled the Southland overnight, just one day before the 20th anniversary of the Northridge Earthquake.
A magnitude-4.6 earthquake rattled Santa Barbara County Wednesday.
The 4.1 earthquake that struck Wednesday night occurred near the Whittier fault, which has produced major quakes in the past, leading some to ask if it was a precursor to something bigger.