PASADENA (CBSLA.com) — Seismologists at Caltech say an early warning system did notify scientists that Sunday’s Napa quake was imminent, but that the system still needs work.

COMPLETE COVERAGE: NAPA QUAKE

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The Magnitude 7.0 temblor injured more than 120 people, set off fires, ruptured gas and water lines and crumbled historic buildings across Napa Valley.

But experts said it could have been much worse. Because the quake struck at 3:20 a.m. most people were asleep.

“That tends to minimize the impact, in terms of injury,” according to U.S. Geological Survey geophysicist Robert Graves.

He said the last big earthquake in the Napa area was a Magnitude 6.4 in the 1800s.

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The cleanup Sunday started before the sun rose and was accompanied by several aftershocks, the largest registering at Magnitude 3.6 just before 6 a.m.

“We may have even larger, even up to Magnitude 4.0 or possibly even Magnitude 5.0,” Graves said. “The aftershocks should die down over the next few days, but still lingering over several weeks.”

Graves said there’s an early warning system that detects earthquake seconds before they strike. It’s still in the developmental stages and Caltech scientists said it alerted them to the Napa quake 10 seconds before it hit.

“The system is in operation throughout the state, actually throughout the entire Western U.S. The system did work this morning,” Graves said.

As for the general public? They had no idea the quake was about to happen.

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Graves said the early warning system needs more funding. He said that within a few years the software will be able to provide the public with almost a minute’s notice before things start shaking up.