4.0-magnitude earthquake near Ontario rattles Southern California

A 4.0-magnitude earthquake near Ontario shook parts of Southern California on Sunday morning, Oct. 6, the U.S Geological Survey reported.

The quake, at 3:51 a.m., was centered at 4.3 miles southeast of Ontario, 4.5 miles north, northwest of Eastvale, 4.9 miles north, northwest of Jurupa Valley and 5.6 miles south of Rancho Cucamonga , according to a preliminary report by the USGS.

It occurred at a depth of about 3 miles.

The quake, centered near S. Archibald Avenue and a few blocks from the Whispering Lakes Golf Course, initially was reported at a 4.1 magnitude, but was later downgraded. It was the latest in a series of temblors at a magnitude of 3.0 or higher in the Ontario area since early September, the USGS said.

Light shaking was recorded throughout the Inland Valley, as well as San Bernardino, Riverside and Orange County and parts of the Los Angeles area.

The quake was followed by eight aftershocks as of 7:25 a.m., including the strongest one, registering a 2.5-magnitude at 4:04 a.m., a senior data analyst at the Caltech Seismology Laboratory said.

“More aftershocks may be expected in the next few days,” Zackary Newman, the analyst, wrote in his report. “The largest expected is approximately 1 magnitude unit smaller than the mainshock.

“There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time,” he wrote.

No injuries or damage were reported on Sunday morning.

On Tuesday, Oct. 1, a magnitude-3.5 quake struck nearby; it was centered two miles southeast of Ontario.