There was a wave of aftershocks after a 4.0 earthquake rattled the Bay Area Friday night. Most describe it as a very sharp jolt, while others say there was more of a rolling motion.
The earthquake struck at 9:00 p.m. and was centered just east-northeast of Alamo, in the East Bay. Seismologists say that's a highly active seismic area.
The quake was felt as far away as Modesto, Watsonville and Napa, and it was quickly followed by four aftershocks ranging from .9 to 1.9 in measure.
For most homeowners, there wasn't any structural damage, only a few things falling off the shelves in some places. At the Safeway in San Ramon, there was no real damage, but some paper products did fall off the shelves.
Some water glasses fell off tables and shattered at a Japanese restaurant and a few bottles broke at a liquor store in Danville.
There weren't any injuries reported, but there was definitely a sense of surprise from a lot of people.
"There was a rather large shake, thought a truck hit the building and it scared us," said Dean Cross of Danville.
"I felt it pretty strong. I was just chilling on my chair, kicking back trying to do some work and looked over to the side. I thought someone crashed into the window and the next thing you know I see the thing just jolt really sharply and I'm like, 'Holy crap. This must be an earthquake,'" said Steve Longmire of San Ramon.
"I was roller skating and something shook and I didn't know what it was, so I went up to some guys and asked them, and he said, 'It was an earthquake,' and I was kind of scared," says Liam Mullin of San Ramon.
The effects were felt as far as East Oakland, which is about 15 miles from the earthquake's epicenter. Cans were knocked off a shelf in one woman's home, but there was no other damage in the home.
One man did say it reminded him a little bit of the Loma Prieta quake in '89.
USGS seismologist David Oppenheimer said the quake was along a fault line that does not have a name because it does not rupture the surface. Oppenheimer said the last time the fault was active was in April 1990 when a sequence of quakes shook the area for three to four weeks.
Oppenheimer said that sequence included 18 quakes of at least 3.0 and caused some structural damage along the fault line.
But he said it's too early to know if this quake will have a similar result. Oppenheimer said the 10-mile depth of the tremor means there was more rock between the quake and the surface, resulting in shaking that was not felt as strongly.
By 10 p.m., there had already been three aftershocks, none of which registered as more than a 1.9.
The quake caused Bay Area Rapid Transit trains to stop systemwide for nine minutes, said spokesman Linton Johnson, who added that stopping trains after an earthquake for about five minutes is protocol.
After stopping the trains, BART officials let the trains run again but at a slower speed so that any damage could be reported back. Johnson said there had been no reports of structural damage to the BART lines.
By 10 p.m., BART was still experiencing delays up to five to 10 minutes.
Officials with the Oakland International Airport, the closest airport to the quake's epicenter, said they did not find any damage when they checked the runways and there were no delays reported.