A moderate, but powerful earthquake struck San Jose just after 8 p.m. tonight, shaking buildings and prompting rattled residents to pour out of their homes.
The temblor on the Calaveras Fault lasted about 30 seconds. The U.S. Geological Survey preliminary magnitude estimate was 5.6, making it the most powerful quake to hit the Bay Area since Loma Prieta, Oct. 17, 1989. That was a magnitude 6.9.
The epicenter was five miles miles from Alum Rock, seven miles from Milpitas and nine miles from San Jose City Hall with the earthquake originating 5.7 miles below ground.
Shaking was felt throughout the Bay Area. Eleven aftershocks with magnitudes of 1.3 to 2.1 were reported by 8:45 p.m.
There were no immediate reports of major damage, though cellular and landline telephone service failed for a time in some areas.
The latest updates:
10:28 p.m.: USGS: Calaveras Fault is one of just a few here capable of major quake
There are literally hundreds, if not thousands of faults, that slice and dice through the Bay Area, but only about 7 or 8 of them are capable of a magnitude 6.7 earthquake or greater, according to Tom Brocher, coordinator of Northern California earthquake hazards investigations for the U.S. Geological Survey in Menlo Park.
The Calaveras Fault is one of them.
But tonight’s earthquake is not necessarily a harbinger of more big or bad quakes to come.
“The earth is constantly groaning,” Brocher said. And the southern portion of the Calaveras Fault, where this quake originated, is known for ‘creeping’ that is slowly and constantly moving.
If anything, Brocher said, the quake serves as a reminder that we live in Earthquake Country.
And the Hayward Fault, which most seismologists suspect of being the site of the Bay Area’s next ‘Big One,’ is primed and ready.
Two weeks ago, earthquake experts gathered in a Hayward museum and pointed out that the Hayward Fault has a major earthquake every 140 years.
This October marks year 139.
10:01 p.m.: Quake brings back bad memories in Santa Cruz
In Santa Cruz, where one in three buildings was destroyed along Pacific Avenue downtown in the 1989 quake, tonight’s shaking brought back bad memories.
“It gave me a sick feeling in the pit of my stomach. It’s more like physical memory than anything else,” said Mardi Wormhoudt, who was Santa Cruz mayor in 1989, and was eating dinner on the Santa Cruz Wharf. “It’s amazing how it comes back. Unfortunately, it brings back so much of what was so horrible.”
Neal Coonerty, owner of Bookshop Santa Cruz, which was destroyed in the 1989 quake and became a symbol of rebirth later, was upstairs in his home when Tuesday’s quake hit. There was no damage, but the shaking was something he hadn’t felt in 18 years and he rushed to call his daughter to find out if she and his new granddaughter were OK.
“It was forceful. It is nerve-wracking. It takes your breath away,” Coonerty said. “You are always hoping the 1989 equarthquake was once in a lifetime. But this is California and we all know it probably won’t be. It is unnerving.”
9:41 p.m.: Scientists not surprised by quake’s magnitude
Earthquake scientists said they were not surprised that a 5.6 quake originated on the Calaveras Fault.
“We think the Calaveras is capable of a quake of maybe even a magnitude 6.4,” said Tom Brocher of the U.S. Geological Survey.
Brocher said that a quake with a magnitude 5.6 typically wouldn’t be associated with a lot of damage: “Maybe things tipping over in grocery stores. Maybe here or there a pane of glass broken,” he said.
Although there have already been aftershocks recorded, they have been minor. Seismologists don’t anticipate another large quake on the fault soon.
“Probably this is the largest we’re going to have,” Brocher said. But there is, he conceded, a 5 to 10 percent chance of an earthquake this size or larger occurring on the Calaveras Fault within the next seven days.
It took some time for seismologists to pinpoint on which fault the earthquake originated. Both the Hayward Fault – which is considered due for the ‘Big One’ – and the Calaveras Fault slice through that area east of downtown San Jose.
When asked if an earthquake so close to the Hayward Fault could ultimately end up setting off a quake on that fault as well, Brocher said he didn’t want to speculate.
“But,” he said, “we’ll be looking at that.”
9:33 p.m.: VTA workers inspecting for damage
Valley Transportation Authority workers are checking the light rail lines for damage and trains have been slowed.
Power went out in sections of San Jose’s Japantown one man said, but at Teske’s German restaurant, not a glass was out place.
Owner Hans Baumann said the place swayed one way and then the other, the chandelier in the main dinning room went up and down and side to side. A diner yelped. And single display bottle of German liquor fell to the floor but didn’t break.
“I knew it was a big one when it started to move in different directions,” he said.
He had been standing near the kitchen watching the basketball game on the TV when the quake struck. “But nothing here broke. It was like that during the last big one too. This is an old building.”
9:16 p.m.: South Bay hospitals report phone trouble, but no major damage
At local hospitals, the lights stayed on, no major damage was reported and patients appeared to be unharmed during preliminary checks – although everyone felt the rolling tremors.
At Regional Medical Center of San Jose, the closest hospital to the quake’s epicenter, spokeswoman Victoria Emmons said the hospital could not make phone calls but could still receive them.
The earthquake was not severe enough to trigger an internal disaster alert at Good Samaritan Hospital, and it appeared only to disrupt some Nextel cellular phones, said Good Samaritan spokeswoman Leslie Kelsay.
At county-run Valley Medical Center, however, five elevators shut down in a building that once housed the main hospital but is now used for outpatient procedures and offices. No patients were in the building at the time of the quake, said spokeswoman Joy Alexiou.
The building was converted into offices because it was deemed seismically unsafe according to a state law that requires hospitals to retrofit buildings to meet higher earthquake safety standards.
“It really does prove the point (about hospital safety),” Alexiou said. “‘We’re feeling very fortunate nothing else happened to us.”
8:31 p.m. Residents in downtown San Jose pour into the streets to check damage
On the north end of San Jose’s downtown, shaken residents left apartments, condos and homes to survey the damage. Luckily it was minor.
The quake shook a metal garbage can into a car parked on the street and at 350 North 2nd a water pipe broke, streaming water into the parking garage of a condo building.
“At first I thought it was a train,” said David Eaton, who lives in the building. “But it went on way too long. And then I heard things starting to fall and I knew it wasn’t the train.”
Although it was Eaton’s first big earthquake, he was prepared. He stood outside of his building with his two dogs, carrying a flashlight and other emergency equipment.
“This building is only two years old but it really shook,” he said.
Down the street near a VTA bus stop driver Christopher Archuleta stood outside of his line 23 bus with a big smile.
“That was fun,” he said shaking his head.
He had been driving when the wheel started to shake and then bus started to sway.
Two of his passengers told him it was their first earthquake. He said the girls seemed nervous and were unable to get their AT&T cellular phone to work, but were able to borrow another passenger’s cell phone to let their friends know they were OK.
8:22 p.m.: Cupertino resident reports ‘entire house shook’
Vishram Dalvi said that his “entire house shook, pictures swayed, a few things fell off. We ran downstairs with the children but everything stopped. I am worried with what they say about the big one being long overdue now- was it every 140 years?”
In Palo Alto, one resident described the earthquake as feeling as if a “big rolling freight train just went through my backyard.”
Within minutes, fire stations in Palo Alto reported in to the dispatch center that there was no damage to their stations.
Mercury News reporters Barbara Feder Ostrov, Paul Rogers,
Intensity map.
According to the United States Geological Survey (USGS) a magnitude 5.6 earthquake, lasting about 30 seconds, struck at 20:04:54 (PDT) on October 30, 2007, with the epicenter being five miles north, northeast of Alum Rock California and nine miles northeast of the center of San Jose.  The actual coordinates given by USGS put it along the border of San Jose and Milpitas in the hills near neighborhoods in both cities. The quake was felt as far away as the California communities of Sacramento, Sonoma, and Los Banos. It was the most powerful quake in the San Francisco Bay Area and Silicon Valley since 1989.

At least ten aftershocks had been reported by 8:35 p.m with magnitudes ranging from 1.3 to 1.8.

Phone service, including cellular phone service, was reported to be down in some areas around the epicenter. Residents and business owners also reported their homes shaking.

According to the USGS, damage could be "moderate to heavy" and Rafael Abreu of the USGS said that the earthquake is considered "moderate," but so far there are "no injuries." The quake was reported at a depth of 9.2 km (5.7 miles).

USGS predicts a 30% chance of strong (magnitude >5) aftershocks in the next seven days, with a 5-10% probability of aftershocks stronger than the main quake. Additionally, USGS predicts approximately 15-40 small (magnitude 3-5) aftershocks.

The USGS reports that the quake was centered on the Calaveras Fault, and was the most powerful earthquake on that fault since the 1984 Morgan Hill earthquake.