"I live off Piedmont Avenue on the second floor, and it really rocked the whole room. It even shook my big piano," said Shirley Harper.
The 9:21 a.m. quake was felt in a wide area of the East Bay, from Berkeley south and as far away as San Francisco to the west and Concord to the east. A police dispatcher in Emeryville said she heard a boom when the quake struck. "It really shook," she said.
The U.S. Geological Survey in Menlo Park said Saturday's magnitude 3.7 quake was 6.2 miles beneath the surface on the Hayward fault. A check with Google Earth showed the epicenter was beneath a hillside lot between Alvarado Road and Amito Avenue in the Oakland-Berkeley hills west of the Claremont Hotel.
The first in the series, a magnitude 3.7 occurred at 7:12 p.m. Wednesday; the second, also a magnitude 3.7, hit at 10:10 p.m. The U.S. Geological Service reported a very tiny, 1.6 micro quake in virtually the same area at 2:23 p.m. Saturday.
The question, Bay Area residents wonder, does this sudden cluster of small quakes mean a big one lies ahead?
"We don't know the answer," David Oppenheimer, a seismologist with the U.S. Geological Survey, said. "All we can give you is our prediction that there is a 27 percent chance of a major earthquake on the Hayward in the next 30 years.
"Historically, we know that within a six-mile radius of these quakes, we have an average of one magnitude 3 to 4 a year," Oppenheimer said. "What is unusual is we've had three in a short period of time. The question is is that unusual?
"We've only been monitoring the Hayward since about 1970. It's a very short time. So we don't know what's unusual," he said. The quakes originated very near the bottom of the Hayward fault and so do large earthquakes, he said.
Harper said the quakes have her and other residents of her building rattled. "The jolts stop our elevator," she said. "I got stuck in the elevator Wednesday for three hours. There was a terrible roar, like a truck had run into the side of the building."
But at least one Oakland resident faces the uncertain future without fear.
Dwight Arline was still in bed when his East Oakland home started shaking Saturday morning. His roommate was spooked, but Arline, an assistant pastor at Mount Sinai Holiness Church in Oakland, was unruffled. To him, the earthquakes are a sign from God.
"We are struggling against one another instead of providing for one another," he said. "God is tired of people not doing what they are supposed to do."
He plans to preach on the successive quakes in the coming weeks and hopes the tremors compel people to "get it together," and love one another. Arline insists that even if Saturday's quake had been the so-called "big one," he wouldn't have panicked.
"Don't be afraid," he said while waiting for the bus on a street curb in downtown Oakland. "If it's your time, you'll be going."