A magnitude 3.5 earthquake shook Southern California on Tuesday afternoon, just after 12:56 p.m. The U.S. Geological Survey confirmed that the epicenter was located less than a mile south of Ontario International Airport, specifically near the intersection of Francis Street and Carlos Avenue. Initially, the quake was reported with a magnitude of 3.1.
Reports indicated that residents felt light to weak shaking across various regions, including the Inland Empire, parts of Los Angeles, and Orange counties, with some even sensing tremors as far away as eastern Los Angeles County and northern Orange County.
Closer to the epicenter, areas such as Ontario, Upland, Chino, and Montclair experienced minor shaking, which on the Modified Mercalli Intensity Scale is characterized by rattling dishes, windows, and doors, as well as potential cracking noises from walls. Some individuals described the sensation as akin to a heavy truck passing by a building.
This earthquake follows a recent pattern in the region, as there have been three additional quakes of magnitude 3 or greater centered in Ontario over the past month. Notably, a magnitude 3.1 quake occurred on Saturday, approximately 4.3 miles northeast of Tuesday’s event. Earlier in September, two quakes of magnitudes 3.5 and 3.9 occurred within about 30 minutes of each other near the Archibald Avenue exit of the 60 Freeway.
In recent weeks, the Malibu area has also experienced seismic activity, recording seven quakes of magnitude 3 and above, including a significant magnitude 4.7 quake on September 12 that raised alarms even for live television broadcasters. The most recent earthquake near Malibu was a magnitude 3.2, which took place offshore, roughly 6 miles southwest of Point Dume.
Additionally, modest earthquakes measuring 3.1 and 3.2 were reported off the Rancho Palos Verdes peninsula earlier in September.
Statistically, California and Nevada encounter approximately 234 earthquakes annually with magnitudes ranging from 3.0 to 4.0. However, Southern California has been particularly active in seismic events this year. Tuesday’s earthquake struck at a depth of 3.5 miles.
Residents are encouraged to report their experiences to the USGS.