For the third time in three weeks, parts of San Diego County have been lightly shaken by an earthquake.
The US Geological Survey says the latest event occurred at 3:22 p.m. Sunday when a 3.5 temblor broke 9 miles west-northwest of Lake Elsinore in Riverside County.
Geologists say the quake originated on the Elsinore fault system, part of which extends through northeast San Diego County.
Sunday’s quake was felt in Fallbrook, Bonsall, Vista, San Marcos, Oceanside, Escondido, Valley Center, Carlsbad, and San Diego, the USGS reported.
A 4.0 quake occurred on the same fault system on Jan. 30. The epicenter was located a few miles away from Palomar Observatory in North County.
And a 3.5 quake occurred near Idyllwild on Jan. 18, along the nearby San Jacinto fault system.
“The Elsinore system has been more actively lately, but this isn’t anything unusual,” said Tom Rockwell, a San Diego State University geologist who has spent decades studying the fault.