A magnitude 4 earthquake shook Southern California early Sunday morning, marking the strongest tremor in a series of minor earthquakes that have occurred near Ontario International Airport over the past month.
The earthquake struck at 3:51 a.m. and was the fifth event of magnitude 3 or greater recorded in Ontario since early September, according to the U.S. Geological Survey.
The shaking was classified as “moderate” in areas near the epicenter, which is sufficient to wake many individuals. “Weak” or “light” tremors may have been felt across a wider region, affecting significant parts of San Bernardino and Riverside counties, as well as areas within Los Angeles, Orange, and some parts of San Diego counties.
Residents from locations ranging from Palmdale to San Diego reported sensations of the earthquake. The USGS encouraged individuals to share their experiences on its Did You Feel It? website.
Prior to Sunday, the largest quake in San Bernardino County’s fourth most populated city occurred on September 7, when a magnitude 3.9 earthquake caused “light” shaking in the vicinity of the epicenter, enough to disturb windows and dishes and visibly rock parked vehicles.
The epicenter of the Sunday quake was located roughly one-third of a mile southeast of the intersection of the 60 Freeway and Archibald Avenue, approximately 500 feet south of Mountain View Elementary School and half a mile east of the Whispering Lakes Golf Course.
Additionally, the USGS reported that its ShakeAlert earthquake early warning system was activated. Residents can obtain the earthquake early warning app for free from myshake.berkeley.edu.
To prepare for potential future seismic events, interested individuals can sign up for the Unshaken newsletter, which offers emergency preparedness tips over six weeks, including recommendations for earthquake kits and essential apps.