MUSCOY, Calif — Southern California was shaken awake Thursday morning after a series of earthquakes, beginning with a preliminary 4.3-magnitude quake that struck just after 9:30 a.m. in the Muscoy area of the Inland Empire, according to the U.S. Geological Survey (USGS).
The quake occurred at a shallow depth of just over three miles, amplifying the sensation of shaking throughout the region. The initial temblor was followed just minutes later by a 3.1-magnitude aftershock near Rialto, only a few miles away. Prior to the main quake, the same area experienced two smaller tremors—a 3.0 and a 2.8-magnitude quake—within the span of an hour, suggesting a cluster of seismic activity in the region.
Shaking Felt Far and Wide
Residents across Southern California quickly took to social media and local news outlets to report feeling the quakes. Reports of shaking came in from across the Inland Empire, as well as from areas as far west as Redondo Beach, nearly 70 miles from the epicenter.
In Jurupa Valley, Eastvale, and Ontario, residents described a sudden jolt, while others farther away noted a rolling or swaying motion.
Gregory Christison shared on Facebook: “I felt it in Garden Grove, in my apartment on the 7th floor. It was a rolling sensation.”
Cindy Hecht Sedbrook, who was on the 11th floor of a building in Irvine, said she felt the quake clearly, adding to the widespread reach of the tremor.
Everthom Ibarra noted the surprising timing of technology and sensation: “I got a notification of an earthquake on my phone, and literally one second after that, it felt so strong. That was more than 4.5, trust me.”
No Immediate Reports of Damage or Injury
Despite the relatively strong jolt and its widespread reach, authorities have not reported any injuries or structural damage as of Thursday afternoon. Emergency services remained on alert but did not activate any large-scale response, indicating that the quake, while noticeable, did not appear to cause significant harm.
The USGS continues to monitor the area for aftershocks, which are common following moderate seismic events. While aftershocks tend to decrease in magnitude and frequency over time, residents are advised to remain cautious and ensure their emergency preparedness kits are up to date.
A Reminder of California’s Seismic Reality
Thursday morning’s seismic activity serves as a fresh reminder of the constant tectonic tension beneath Southern California. While a 4.3-magnitude earthquake is considered moderate, its shallow depth and proximity to densely populated areas heightened its impact and visibility.
Experts emphasize the importance of preparation. Southern Californians are urged to review emergency plans, secure heavy items in homes and offices, and ensure mobile phones have earthquake alert systems enabled, such as ShakeAlert, which gave many users advance notice just seconds before the shaking began.
As the state continues to live with the reality of seismic activity, events like this underline the need for community readiness, personal safety awareness, and respect for the powerful natural forces at play beneath our feet.
Stay safe, Southern California.
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