Three small earthquakes hit in the Inland Empire on Wednesday morning.
A shallow magnitude 3.1 earthquake was reported six miles from Corona, according to the U.S. Geological Survey. The temblor occurred at 9:11 a.m. at a depth of about 4 miles.
Earlier, a magnitude 2.7 earthquake was reported two miles from San Jacinto. It was originally reported as a magnitude 3.1. The temblor occurred at 2:19 a.m. at a depth of about 9 to 10 miles.
That quake occurred shortly after a 3.7 magnitude temblor hit in the same area at 12:39 a.m. It was originally reported as a magnitude 3.9.
The first two earthquakes most likely occurred in the San Jacinto fault zone, which scientists consider very active, Caltech seismologist Jennifer Andrews said.
"We see relatively small earthquakes [on the San Jacinto fault], but it's relatively active," she said.
Scientists are still studying the details of the third earthquake, which occurred near the Elsinore and Whittier faults, Andrews said. There is no reason to think this quake was connected to the first two, she said.
Both Elsinore and San Jacinto are major fault zones in Southern California and run approximately parallel to the coastline.
Read more about Southern California earthquakes.