ShakeAlert is activated when a 4.2 magnitude earthquake impacts Northern California.

ShakeAlert is activated when a 4.2 magnitude earthquake impacts Northern California.

ShakeAlert is activated when a 4.2 magnitude earthquake impacts Northern California.

According to early data from the USGS, a 4.2 magnitude earthquake occurred in Sacramento County on Wednesday morning.

According to the agency's website, the earthquake, which occurred at 9:29 a.m., was located close to Isleton.

Wednesday morning, Devery Stockon, manager of the Owl Harbor Marina in Isleton, stated, "It felt like an 18-wheeler ran into the building." 

The marina's office was shaken for roughly a minute, according to Stockon, but the facility, which is situated close to a San Joaquin River inlet and is built on stilts, did not appear to sustain any long-term damage. According to USGS, the location is less than a mile south of the earthquake's epicenter, which was on Brannan Island in the confusing network of waterways that makes up the Sacramento-San Joaquin Delta. 
According to the USGS's crowdsourced intensity map, residents of California reported feeling minor shaking as far north as Sacramento and as far south as Stockton. 

Employee Cindy Gollihar at the sizable Vieira's Resort between Isleton and Rio Vista said she was "on the phone with one of our customers, and this is a metal building, so it was a huge jolt, and I'm freaking."

Although some items fell from shelves and walls, according to Gollihar, there was no significant structural damage. According to her, she got a ShakeAlert "probably 3 minutes after it happened."

• Mapping the most recent earthquakes in California and around the world using an earthquake tracke

• Initial warnings suggested a stronger earthquake had occurred, but the USGS quickly revised their assessment to lower the quake's magnitude to 4.1. 

The USGS community Did You Feel It? map had received almost 3,000 reports by late Wednesday morning that the earthquake had been felt broadly throughout the Sacramento region and the Bay Area, with the majority rating the strength as mild to light, with the exception of the Isleton area, where it was moderate to severe.

Due to the earthquake, certain BART trains in the Bay Area were briefly suspended but shortly resumed. 

San Ramon and the center of Brentwood were among the Bay Area locations where the tremor was felt. 

Smartphones in San Francisco flashed earthquake alarms, but the majority of early reports suggested that just a few locations, including the city's Panhandle, felt the quake's full force.