The 4.1-magnitude earthquake that rattled the Bay Area Thursday morning is nothing to be shaken up about, a U.S. Geological Survey geologist said.
"Right now this is sort of your run-of-the-mill earthquake," USGS senior earthquake geologist David Schwartz said of the temblor that struck at 10:09 a.m. "In reality it's not a big deal."
The earthquake occurred on the Calaveras fault about 5.6 miles beneath the ground's surface. It was centered six miles east-northeast of Milpitas and eight miles north-northeast of Alum Rock.
Schwartz said people as far away as Santa Rosa and Carmel felt the shaking. There were no immediate reports of serious damage.
The Calaveras fault experiences several 3.0- to 4.0-magnitude earthquakes each year, Schwartz said. "It's a reminder to everybody that we are in an earthquake area," he said.
To give some perspective, Schwartz said a magnitude 6.0 earthquake would have been 900 times more powerful. Had the quake had a magnitude of 5.0 or greater, there would be more cause for concern, he said.
"We know from looking at statistics in California that when we have a 5.0 quake, there is a 5 to 10 percent chance that in the next 72 hours, it will be followed by a larger earthquake," Schwartz said.
"We don't really see that with magnitude 4's," he added.
Thursday's quake was followed by nine aftershocks ranging in magnitude from 1.2 to 2.3, he said at about noon. Aftershocks could continue for several days, he added.
Milpitas police Sgt. Daryl Sequeira said the department received a number of calls about the earthquake, but that most were from the media.
Sequeira said he felt the temblor, which he said shook the building for two or three seconds. "Nothing even fell off my shelf," he said.
Deanna Melen, an employee at Roadrunner Glass on South Main Street in Milpitas, said the earthquake frightened her, especially since she was the only one in the office at the time.
"It was a little bit scary," Melen said. "I did hear a few things fall, so I have to go check it out. I sat under my desk for a while though.
Students at Lowell Elementary School on South Seventh Street in San Jose responded by dropping to the floor and applying the duck-and-cover method before evacuating, school secretary Veronica Alvarado said.
"Our drills have been helping," she said. "Our kids did great."
Alvarado said the earthquake was "shocking," but said there were no reports of damage or injuries.
Roqua Montez, spokesman for the Tech Museum of Innovation in San Jose, felt the earthquake too. "The building swayed back and forth for what felt like minutes," he said.
Three months ago, Montez was helping host a "Great California Shakeout" event at the museum aimed at preparing middle and high school students for a major earthquake. He encouraged residents to visit the museum's earthquake simulation exhibit.
"Downstairs we have an actual earthquake platform, which simulates earthquakes from around the world," he said. "Children learn about the U.S. Geological Survey, why we have quakes, and when and where they've occurred," he said.
The earthquake caused slight delays to BART trains and Santa Clara Valley Transportation Authority light rail vehicles because both agencies' earthquake protocols called for brief stoppage of service.
The Santa Clara County Office of Emergency services is reminding residents keep disaster supply kits at home, at work and in the car, and designate a place to meet up with family members in the event of an emergency.
Disaster kits should include provisions such as water, food, first aid supplies, clothing, bedding and tools.
The American Red Cross recommends keeping on hand a three-day supply of water -- one gallon per person per day -- as well as a flashlight, extra batteries, cash, matches in a waterproof container and a utility knife.
More Red Cross disaster preparedness tips can be found by visiting www2.redcross.org/services/disaster/ and clicking on "Be Prepared."
"Earthquakes are a fact of life in California, and it's really important that residents take steps to ensure they're prepared," Santa Clara County spokeswoman Gwendolyn Mitchell said.