Southern California was rattled Thursday morning after a 4.3-magnitude earthquake struck near the Muscoy area in the Inland Empire, just after 9:30 a.m., according to the U.S. Geological Survey (USGS). The shallow quake, with a depth of approximately 3.2 miles, was widely felt throughout the region.

Series of Tremors Reported in the Region

The seismic activity wasn’t isolated. Earlier in the morning, two smaller quakes occurred near the Rialto area—first a magnitude 3.0, followed closely by a 2.8. Just minutes after the main 4.3-magnitude event, the same area experienced another magnitude 3.1 quake.

“This is an active area,” said Dr. Gabrielle Tepp, seismologist at Caltech. “This region lies close to where the San Jacinto Fault meets the San Andreas Fault, both of which are significant fault lines in Southern California. We frequently see seismic activity here, particularly in the 4.0 range.”

Residents React to the Sudden Jolt

The quick, sharp motion caught many off guard. Local residents took to social media platforms to share their reactions and personal experiences.

“That was a big jolt! No rolling—just a quick shake,” one Riverside user commented.

“Felt it in Riverside. It started with a roll, then a sharp shake,” another reported.

Reports of the shaking came from as far away as Los Angeles and Orange County, though the strongest impact was felt closer to the epicenter.

8.8 Magnitude Quake Near Russia Prompts Pacific Tsunami Alerts

This quake follows global seismic concerns triggered by a massive 8.8-magnitude earthquake that struck near Russia’s Kamchatka Peninsula just days earlier. That event prompted tsunami advisories for portions of the U.S. West Coast, Hawaii, and Guam.

The West Coast experienced mild wave activity late that evening, with initial impacts reported around 11:40 p.m. PST, according to Fox Weather. In Hawaii, state officials warned of potential wave arrivals around 1:17 p.m. HST on July 30.

Although the tsunami warning in Hawaii was later downgraded to an advisory at 10:39 p.m. HST, evacuation orders had already moved residents to higher ground as a precaution.

This 8.8 quake is now considered the most powerful seismic event since Japan’s catastrophic 9.0-magnitude earthquake in 2011, which led to the Fukushima Daiichi nuclear disaster.

What’s Next for Southern California?

Seismologists advise residents to be prepared for aftershocks in the wake of Thursday’s tremors. While no major damage or injuries have been reported, authorities continue to monitor the region for further seismic activity.

Residents are encouraged to review their earthquake preparedness plans and ensure emergency kits are up to date.

Stay tuned to local emergency management agencies and geological updates for the latest developments.