(07-20) 11:47 PDT OAKLAND -- The 4.2 magnitude earthquake that rattled the Bay Area early today broke a few windows, swept merchandise off shelves and photos off walls and temporarily cut power to thousands of people in Oakland, but it caused no major damage or injuries, officials said.
Some grocery stores and other businesses in Oakland and Berkeley reported minor damage this morning and workers were busy putting fallen items back on the shelves.
At the Safeway on Shattuck Avenue and Rose Street in North Berkeley, employees had to delay opening while they cleaned up and replaced two panes of glass that broke during the quake.
At UC Berkeley's Boalt Hall library, there was also damage to some 19th century Swiss law books, which had their bindings ripped off when they fell alongside a few hundred other books on the sixth floor. The Louisiana state law section took a big hit as well.
And Dream Fluff Donuts in the city's Elmwood District had a large, oval shaped piece of glass fall out of their display window, but remained open for business.
"It was all pretty minor," said U.S. Geological Survey spokeswoman Leslie Gordon. "It didn't interrupt doughnut production."
Alex Sieu, who has owned the shop for 20 years, said the quake seemed worse than the 1989 Loma Prieta earthquake, which registered a 6.9 magnitude. He was standing near the front of the popular bakery when the window broke, he said.
"I thought somebody threw a cinderblock," he said, adding that he does not have earthquake insurance and will have to pay out-of-pocket to replace the pane. "You know it won't be cheap."
Sieu did have to trash more than 100 donuts that had been sitting in the display case and were covered in glass. But customers were there all morning, purchasing the newly baked pastries.
Electricity failed for about 4,600 people in Oakland after the 4:42 a.m. temblor hit, said Pacific Gas and Electric Co. spokesman David Eisenhauer. Only two customers remained without power at 10 a.m. - including the KTVU television studio in Jack London Square.
The outages were caused when an underground switch was damaged by the initial jolt, he said.
"The jolt shook the switch and caused it to fail. That set off a chain of events in our protective equipments -- fuses and circuit breakers that shut off to protect the rest of the system," he said, adding that the switch needs to be replaced, so the television station will remain without power for a while and will have to continue running on a generator. "The switch was in their backyard."
Gordon said the quake was centered about 2 miles northeast of downtown Oakland on the Hayward fault. The actual epicenter was in the Oakland Hills near Joaquin Miller Park and the Mormon Temple, according to an online topographic mapping service that works with the USGS. The area is called Butters Canyon.
The quake awakened Carol Bernau, who lives in Butters Canyon.
"My husband and I were jolted awake. It was almost like somebody was trying to move the bed," she said.
Still, USGS's Gordon said, "We consider that a light earthquake. It's not unusual. I know it was felt fairly widely, as far north as Sonoma. There was weak to light shaking in most areas."
Dale Risden and his partner also were awakened by the quake. The couple live on Crane Way, just off Joaquin Miller Road and only steps from the quake's epicenter.
They checked their house carefully to see if there was any damage and found none.
"It felt like it was right under me," said Risden. "I normally don't get startled by an earthquake but that one startled me. It just really shook me. It woke us out of our sleep."
Three-year-old Maddy Cometa, who lives in Montclair, also was sleeping soundly when the rattler hit.
"Something woke me up -- my mirror shook," said Maddy as she and her tired father, Tom, walked to Starbucks this morning.
Cometa said it was the worst quake he could recall in his 15 years in the Bay Area, adding that it knocked down pictures and knickknacks in their Oakland home.
Karen Toloui said several bricks fell from the chimney of her Scenic Avenue home in Berkeley, and her neighbor's fireplace now just 2 inches from the wall.
"It seemed stronger than a 4.2," she said.
Other Oakland residents reported less than five seconds of shaking, but said the initial jolt was strong.
"Anytime the earth moves beneath you it's a little unsettling, no matter who you are," said USGS seismologist Rufus Catchings, who felt the temblor. "This is the biggest (quake) we've had in a while."
Catchings noted that the Loma Prieta earthquake lasted a whopping 15 seconds. He said it would be normal for residents to feel this morning's rattler for a few seconds, but that it wasn't strong enough to last much longer.
He did not know the exact duration of the quake.
"This was a strike-slip mechanism," he said. "These give very strong, if you're nearby, initial jolts from the (primary) wave and then rattling for a couple seconds from the (secondary) wave."
It's possible that the temblor was a foreshock that could be followed by stronger seismic events, said Catchings.
"To be very honest, we can't tell, but we do look at that kind of thing, and it's not unheard of for something like this to be followed by something larger," he said.
Several business owners in the Montclair District, about 2 miles from the epicenter, arrived at work today to find their merchandise in shambles.
The Toyhouse Montclair Store had a few inches of toys strewn across its aisles, including the casualties of a stuffed yellow duck and a tricycle that fell from the top shelf. A.G. Ferrari Foods nearby lost several bottles of wine to the quake as well.
The shelves at Sullivan's Montclair Pharmacy were emptied of their shampoo and sunscreen bottles, and drugs littered the floor behind the counter. Owner Joe Sullivan assured customers, however, that his boxes of Harry Potter books -- which go on sale at midnight -- were untouched.
"Harry survived," he said.
Sullivan is convinced that the Hayward Fault runs through his store, and pointed to a crack down the middle of the property as proof. The floor on one side of the crack is about a half-inch below the other side.
Sullivan said he learned of the rattler when his adult son, Ryan, woke up and yelled "earthquake." He ran in and told him it was a bad dream and to go back to sleep.
"At this point, yes, (I believe him)," Joe Sullivan said.
Gordon said about 5,500 people registered this morning to access a map on the USGS Web site, which allows the public to report where the earthquake was felt and how strongly. The map shows weak to light shaking in the East Bay and North Bay, as well as San Francisco and the northern area of the Peninsula.
"They didn't feel it in San Jose. ... Most areas reported weak to light shaking and those closest epicenter reported moderate shaking," she said.
Gordon said the quake was not unusual, but she and Catchings warned that Bay Area residents need to prepare for the "big one."
"I want to tell people that it was both figuratively and literally a wake-up call this morning," she said. "Just be ready -- this is totally normal."
Risden, the resident who lives near the epicenter, said the quake will prompt him to prepare.
"Keeping things from falling on you is key," added Catchings. "Something much bigger could happen, and people should take this as a lesson to prepare, figure out what your plan is going to be, make sure you have stuff to survive the really big one."
Oakland City Councilwoman Jean Quan, who represents the district that includes most of the Oakland Hills and straddles the Hayward Fault, said she had just been researching the damage from the recent Japan earthquake to see if the city could offer any gestures of aid or friendship.
"I was thinking about earthquakes when I went to bed and then a quake woke me up," Quan said.
This summer, she successfully sponsored legislation that encourages homeowners to retrofit their dwellings.
The measure lowered the price of a retrofitting permit to a flat $250 -- a fee that formerly could cost more than $1,000. Her legislation also allows home buyers to get a rebate of up to $5,000 on their city transfer tax if they retrofit their homes. Also starting next year, some homeowners can get grants for retrofitting. Only 15 percent of Oakland homes have been retrofitted, Quan said.
"I've been thinking about and planning of earthquakes for a very long time," Quan said. "We know an earthquake is coming."
Chronicle reporter Jim Herron Zamora contributed to this report. Chronicle reporter Jim Herron Zamora contributed to this report.
Un terremoto de 4,2 grados en la escala de Richter sacudió el Área de la Bahía de San Francisco el viernes. Se reportaron caída de objetos pero aún no se reportó ningún herido.

Según reportó el United States Geological Survey, el terremoto tiene su epicentro a 2 millas al noroeste de Oakland. El terremoto ocurrió a las 4:42 a.m. y sacudió el área del la Bahía de San Francisco.

Al menos 1.000 personas fueron cortadas temporalmente del suministro eléctrico en Oakland, reportaron oficiales. Sin embargo, rápidamente se recobraron los servicios.

"No se reportaron daños importantes, y nuestro persona está trabajando para reestabilizar la energía en el resto de nuestros clientes", dijo Susan Simon, una portavoz oficial de Pacific Gas and Electric Co.