4.7-Magnitude Earthquake Near Brawley Felt Across Southern California Amid Seismic Swarm

Southern California was rattled by a swarm of earthquakes over the weekend, with many centered near Brawley in Imperial County.

The strongest quake was a 4.7-magnitude tremor that struck at around 12:10 a.m. on May 10, 2026, around 3 kilometers west-southwest of Brawley, according to the U.S. Geological Survey (USGS).

The epicenter was located at a depth of 14.5 kilometers.

The tremor was felt in several areas farther away from the epicenter, including Palm Springs (130 kilometers from the epicenter) in Riverside County and San Diego (nearly 150 kilometers from the epicenter).

The USGS activated its ShakeAlert warning system for residents, which sends out alerts to cell phones by the agency’s Alert Delivery Partners.

The seismic event was initially categorized as a 4.2-magnitude earthquake and was later revised to 4.7, USGS shared in a social media update.

Nearly 190 people reported feeling the tremor through the USGS’s ‘Did You Feel It?’ reporting system.

Residents near Brawley reported feeling strong shaking, while those in farther-away locations, such as in Carlsbad, Fontana, Los Alamitos, and Parker, reported light shaking.

The intensity of the earthquake was categorized as Level VI, which indicates strong shaking and light damage.

Intensity of an earthquake signifies how strongly the shaking was experienced at certain locations, while magnitude determines the earthquake’s energy.

The USGS initiated a Green Alert for the seismic event, which means there is a low possibility of casualties and damage.

USGS warned that the area could experience at least one aftershock within the next week, with the aftershock rates expected to decrease over time.

This earthquake was among multiple earthquakes that struck the region over the weekend. Most of them were below magnitude 4.

Early morning on April 11, 2026, a 2.5-magnitude quake rattled near Brawley.

Occurring at about 2:13 a.m., the earthquake’s epicenter was located 4 kilometers south of Brawley, at a depth of 14.2 kilometers.

So far, only one person reported feeling the shake on USGS’s ‘Did You Feel It?’ tool. The seismic event was categorized as Level II intensity, which indicates weak shaking and no damage.

There were no reports of casualties or damage caused by any of the earthquakes.

These earthquakes occurred at relatively shallow depths, which usually result in stronger shaking than deeper ones.

Until 6 p.m. Sunday, the USGS had recorded 373 earthquakes that occurred in Imperial County, which started from early morning on Saturday, according to FOX5 News.

What is a Seismic Swarm?

The sudden increase in seismic events near Brawley is due to seismic swarms, the USGS explained on X.

The USGS defines a seismic swarm as a series of earthquakes that occur close together in the same region, but do not follow a clear main earthquake followed by smaller aftershocks.

Typically, in an earthquake sequence, the biggest tremor is followed by minor ones that gradually decrease over time.

However, in a swarm, multiple earthquakes can be similar in size. The strongest one may happen in the middle of the sequence, with the activity continuing steadily or even increasing over the next few days or weeks.

According to scientists, seismic swarms are often associated with underground processes, including the movement of fluids through faults, slow fault movement, or sometimes magma pushing through rock.