Santa Cruz, California - The shaking felt across the Central Coast this morning was more than the small earthquakes near Tres Pinos and the Los Altos Hills. Apparently a sonic boom is to blame.

The mysterious door and window rattling felt about 9:15 a.m. across Santa Cruz and Monterey counties wasn't an earthquake, according to the U.S. Geological Survey.

The sonic boom was so powerful that USGS seismometers on the ground picked up the movement.

A magnitude 2.0 earthquake hit about 8:40 a.m. this morning about a mile from the Los Altos Hills. Then at 11:12 a.m. a 1.7 movement was measured in a quarry near Portola Valley. The USGS attributed that to a probable quarry explosion.

"Our best guess is that it was a sonic boom from a jet of the coast of Monterey Bay," said Leslie Gordon with the USGS.

Steve Bauer, a public affairs officer at Vandenberg Air Force Base says he has no information about any activity off the coast this morning.

"If anything like that had occurred, we would have been notified," Bauer said.

Robert Diller, who lives on Glen Haven Road in Soquel, said he heard four loud booms this morning, first before 10 a.m. and then again around noon, two each time in succession.

"They made our windows rattle," Diller said. "It was like a blast, it sounded like a dynamite blast almost."

Diller said he didn't feel the earth move as others have reported.

Emergency dispatchers at the county's communications center said they too received calls this morning from concerned residents. They chalked it up to thunder.

A 1.3 magnitude quake hit just outside Tres Pinos at 5:42 a.m. and a 1.6 magnitude at 7:52 a.m. also outside Tres Pinos.

An Aptos woman she felt "what could have been an earthquake or sonic boom this morning - it shook our sliding glass window, loudly" about 9:17 a.m.

"It just happened again, twice in quick succession, at about 12:20 p.m.," said Julie Drysdale. "I was outside and heard two loud booms. My husband said the house shook quickly, like a truck hit it. Not the typical earthquake shaking, much quicker."

Source: Santa Cruz Sentinel