A 3.9 earthquake reported one mile from San Juan Capistrano on Monday was felt in Newport Beach, Costa Mesa and other parts of Orange County.
The temblor occurred at 10:37 a.m., according to the U.S. Geological Survey.
Police in Costa Mesa, Newport Beach, Huntington Beach and Fountain Valley did not receive any reports of damage.
Monday's earthquake allowed scientists to gather more information about the O.C. fault line.
"For residents of the area it's a reminder," said UC Irvine seismologist Lisa Grant Ludwig. "We have that potential for one in south Orange County."
The source of the quake appeared to be in the San Joaquin Hills on a blind fault that gave scientists an opportunity to look at the fault, which has no visible signs from the surface, said Ludwig.
"It's going to tell us quite a bit about the faults in the San Joaquin Hills," Ludwig said.
Residents as far south as San Diego and as far east as Indio reported to the USGS that they felt the quake.
The Newport Beach Fire Department is hosting a workshop on earthquake and tsunami threats from 6:30 to 8 p.m. Thursday at the OASIS Senior Center, 801 Narcissus Ave., Corona del Mar, according to department spokeswoman Jennifer Schulz.
— Lauren Williams and Michael Miller