For many Bay Area residents, Monday morning began with a rude jolt.

A 4.3 magnitude earthquake centered beneath Berkeley, Calif., rattled windows and woke up thousands of people across the densely populated Northern California region at 2:56 a.m., according to reports from the U.S. Geological Survey.

The earthquake along the Hayward Fault, which runs beneath much of the Bay Area, didn’t cause significant damage, based on initial reports.

According to the intensity scale that earthquake scientists use, the shaking from Monday morning’s temblor was considered light. That scale describes such an earthquake as causing almost no damage, though it might have felt to many like a “heavy truck striking a building,” said Angela Lux, a scientist at the Berkeley Seismology Lab.

“People don’t like to hear that, because they feel like they were going to die,” Ms. Lux said. “It’s a great reminder to people that this is what ‘light shaking’ feels like. The Hayward fault is capable of a really big earthquake”

The Hayward fault, which runs directly beneath the University of California, Berkeley campus, last experienced a major earthquake in 1868 — a 6.8 magnitude quake that killed 30 people and is considered one of the most destructive in California history.

Scientists say the fault is overdue for another violent rupture. A 6.8 earthquake would be more than 5,600 times stronger than Monday morning’s quake, according to U.S.G.S.

The temblor on Monday was felt across the bay in San Francisco, and as far away as Sacramento, about 75 miles northeast, according to U.S.G.S. reports.

Hannah Halpern, who lives in Oakland, said her dog had jumped off the bed when the shaking began, and she wasn’t able to get back to sleep. She started to think about what might happen in a bigger quake, and the large metal artwork that hangs above the bed.

“My husband and I leaned across the bed and held hands,” said Ms. Halpern, 29. “For whatever reason, last night’s got to me.”

Though the magnitude of the temblor was not severe, it was centered in one of the most heavily populated parts of the Bay Area. Nearly 300,000 people received early warning alerts from the state, advising them to take shelter. Many remained awake for some time as they braced for aftershocks.

“It’s a very wide swath of a very populated region,” said Robert-Michael de Groot, an earthquake scientist who helps run the U.S.G.S. early warning system. Because of where the quake struck, he said, it was clear that “a lot of people were going to feel it.”

The earthquake might have been particularly jarring because it happened at night, he said. People are more likely to feel the shaking when they are lying in their beds than they are when driving.

The earthquake was centered 5 miles below ground, and only a few blocks south of U.C. Berkeley’s campus.

In general, the people living closest to the epicenter are the most likely to feel a quake. But those who live in homes built on softer ground are likely to feel more shaking, and, in a more severe earthquake, experience damage. Those sorts of places include the Marina District in San Francisco and West Oakland, where many buildings collapsed during the 1989 Loma Prieta earthquake because they sat on less stable ground, he said.

Bryan Hillebrandt, 58, said his “entire house creaked” in Oakland during Monday’s earthquake, which he felt like a jolt through his house.

“I lived through the ’89 earthquake, so it took me a little while to calm down and be like, ‘OK, it’s going to be all right,’” he said.

Feeling the earth quake has long been something of a rite of passage for U.C. Berkeley students, said Ms. Lux, who recalled experiencing it when she was an undergraduate there. But, she noted, there hadn’t been many recently in the region.

There could be aftershocks in the coming days. These are usually smaller quakes, adjustments along the portion of a fault that slipped at the time of the initial earthquake.

Ms. Lux said that there was a small chance of a larger quake within the next week. The chance of one of magnitude 4.0 or higher is 2 percent, and one with a magnitude of 5.0 or above is .2 percent, or 1 in 500, according to U.S.G.S.

“This could be a foreshock,” she said, “but we won’t know that until the earthquake happens.”

Margarette Williams, 71, said Monday’s quake jostled her awake as it lifted up her bed in Oakland. But she went back to sleep easily.

“I’m an earthquake baby,” she said. “I was born in California, so it’s nothing new to me. Other states, they get hurricanes. We get earthquakes.”