This latest aftershock, one of several, was reported around 3:08 p.m. It happened east of Seven Trees with a depth of 7.4km also on the Calaveras fault.
USGS says the main 5.1 quake hit around 11:42 a.m. 12 miles east of San Jose on Calaveras Fault. It initially registered as a 5.0 earthquake but was later upgraded.
There was a 3.1 aftershock reported in the area at 11:47 a.m., USGS said.
ABC7 News has received reports of shaking all across the Bay Area and as far south as Santa Cruz. Thankfully, there have been reports of any injuries or significant damage.
According to ABC7 News Meteorologist Drew Tuma, 5.0 earthquakes are pretty rare in the Bay Area. He wrote on Twitter, "In the past 30 years, we've only had three others. Back in 2000, a magnitude 5.0 was reported in Yountville, in 2007, a magnitude 5.6 struck Alum rock, and the magnitude 6.0 in Napa in 2014."
Numerous moderate earthquakes have occurred along the Calaveras Fault, including the 6.2 Morgan Hill earthquake in 1984, Annemarie Baltay, a seismologist with the U.S. Geological Survey, said in a video statement posted on Twitter.
Seismologist Dr. Lucy Jones joined ABC7 News to break down Tuesday's earthquake and the Calaveras Fault.
"The Calaveras moves more slowly, it has less of the total motion going on there than on the San Andreas, so it moves less often or releases less energy. But it seems to have the smaller earthquakes a lot more often," said Dr. Jones. "It's considered capable of a six and a half or so 6.7. But unlike the San Andreas, it's not going to have, you know, a magnitude eight."
Nearly 100,000 people reported receiving a warning before the shaking started through California's earthquake early warning system, according to the California Governor's Office of Emergency Services, or Cal OES.
VIDEO: Shaking from SJ quake causes art to swing in SF classroom
"Advance notice varied from two seconds for those very near the epicenter to 18 seconds for those in San Francisco," the agency said.
MyShake, a statewide cellphone app that went live to the general public in late 2019, relies on an earthquake detection and notification system developed by the U.S. Geological Survey and partners.
"In San Francisco, because the waves had to travel up from south of San Jose, they would have had a decent amount of warning," said Dr. Lucy. "But of course, if you were actually in Alum Rock you're shaking is what allowed the others to know."
Dr. Jones went on to warn that the Bay Area should expect more aftershocks and there is a five percent chance that one could be larger than the original quake.
People who live and work in the South Bay, are agreeing with what experts confirmed, that this is the strongest earthquake felt in the last eight years.
South Bay business owner Randy Musterer was driving at the time of the quake.
"I felt the road uneven and I didn't really think anything except "Is there something wrong with my car or tires," he said. "Then a couple minutes after, I got a couple text messages saying 'Did you feel the earthquake?'
Though thankfully there were no reports of injury or major damage, a Campbell restaurant owner said the shaking did cause some minor damage.
"We were making the new wine list for our restaurant and we felt a little bit of the shaking," said Annalisa Luongo who co-owns Locando Sorrento. "A few bottles dropped off from the bar and the shelves, we realized it was an earthquake."
Customers in the restaurant at the time struggled to process what was happening in the moment.
"We heard stuff falling off the shelf," one customer told ABC7, "I just thought somebody had dropped something, a plate you know that's what it sounded like."
In addition to the wine in front of the bar, the owners at Locando Sorrento say food on prep tables in the back fell to the ground.
All of this forcing them to re-think their setup in the event of another earthquake.
"We have like a big wine room in the back and we have a lot of wine,"Luongo said, "We need to place the wine in a different way so that if something like that happens, everything can be in place."
ABC7 News reporter Leslie Brinkley and her photographer were in the East Bay when the quake hit but did not feel anything.
However, there were a few people who said they felt the shaking and it all depended on where they were.
Carla Ingram was at work in Alameda when the quake struck.
"I was sitting there and I heard a little rolling and I sat there a little and then felt the swaying and was like oh it's an earthquake it's an earthquake," said Ingram. "I was the only one at work that felt it. I told people 'it's an earthquake, it's an earthquake' but they said no it wasn't. I said 'yes it was, yes it was.'"
Down in San Leandro Gimberto Garcia was lying in bed with his newborn.
"I started feeling a little rattled and I was like oh gosh so I grabbed my baby but it went away as I grabbed my baby. It was a little scary," said Garcia.
Quan Pham was on the 7th floor of a 9-story apartment building in Oakland.
"I just felt my building swaying back and forth. Nothing fell off (the shelves). It only lasted a couple of seconds or so," said Pham.
But everyone agreed it was a bit of a wake-up call.
Several commuter train companies, including Cal Train and BART, held trains to check for damage. BART returned to normal service by early afternoon.
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The Associated Press contributed to this article.