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Earthquake with 4.3 magnitude strikes near Fontana
A map shows the location of where an earthquake struck near Fontana.
(
USGS
)
An earthquake with a magnitude of 4.3 struck about 5 miles from Fontana around 9:30 a.m. Wednesday and was felt around Southern California.
Some people likely received an early warning from the U.S. Geological Survey’s system.
People reported feeling light shaking in Koreatown and Pasadena. Noticeable aftershocks were reported in Riverside.
There was a magnitude 3.1 aftershock a few minutes after the earthquake, according to Caltech seismologist Gabrielle Tepp.
Tepp said the area around Thursday's shaking has a history of quakes. There was a 4.2 magnitude earthquake close to where today's earthquake hit last year, according to Tepp. The largest earthquake in the area was a 5.2 magnitude quake in 1970.
Lucy Jones, an earthquake and disaster expert, wrote on social media platform Bluesky about the quake's location and fault: "Looks like a small swarm in the Fontana trend. This M4.2 had a few foreshocks including a M3.0. The Fontana trend is a NE-striking lineation of earthquakes under the sediments of the San Bernardino Valley. We believe it is one of the left-lateral striking faults that are south of the San Gabriels."
Yes Southern California, that was an earthquake you just felt. Today's reminder that California is earthquake country. Preliminary estimate M4.4 north of Riverside, near town of Muscoy. If you felt it please let us know. https://t.co/USSP959D2r pic.twitter.com/LwTqNx2iMc
— USGS Earthquakes (@USGS_Quakes) July 31, 2025
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Damage from the quake appears to have been minimal. The San Bernardino County Fire Department had not received reports of damage or injuries in the immediate aftermath, according to spokesperson Ryan Beckers.
" It gave us a pretty good little jolt for a few seconds," Beckers said from the Fire Department's headquarters in San Bernardino.
He said any earthquake is a reminder to residents that they should be prepared for an even bigger jolt.
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We don't want to scare you, but the Big One is coming. We don't know when, but we know it'll be at least 44 times stronger than Northridge and 11 times stronger than the Ridgecrest quakes in 2019. To help you get prepared, we've compiled a handy reading list:
- Your guide to surviving the Big One
- For earthquakes, forget the 'go-bag.' Here's how to prepare
- How to not get life-threatening diarrhea after a major earthquake
- 10 earthquake-related questions to ask your landlord immediately
- How to prepare for an earthquake if you have a disability
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