Sonic booms occurred near Los Angeles and Santa Cruz

Film of sonic boom creation http://www.youtube.com/watch?v=uQ2pkmISOLM

http://sciencedude.freedomblogging.com/2009/03/03/small-quake-felt-across-orange-county/20853/
The mysterious door and window rattling that thousands of people felt across Orange County Tuesday night about 9:15 p.m. was likely caused by a sonic boom produced by a high speed jet, says Bob Dollar, a seismologist at the U.S. Geological Survey.
“This morning Kate Hutton (of Caltech) reviewed seismograms from the event last night,” Dollar said in an email. “These data are consistent with a sonic event coming onshore near Dana
Point and traveling northward inland.

“The energy travelled across our seismic sensor network at the velocity of a compressional wave in air rather than the velocity of a similar wave through the ground, which is”"much faster. There was no S phase.

“Additionally, the felt descriptions (doors & windows being rattled but no building shaking) is consistent with a compressional wave such as a sonic but with no shear wave which one would expect in an earthquake.”

The F/A 18 Super Hornet fighter jets used in Southern California by the Navy and Marines are capable of breaking the sound barrier and producing a sonic boom felt on the ground. The same thing happens locally when the space shuttle lands at Edwards Air Force Base. There are currently no shuttles in flight.

The weirdness of the event was captured by a simple message from Sherry Jacobs of Cypress who wrote, “I felt strong rattling of my patio door. I looked outside to check for strong winds and was surprised to find my wind chimes still.”

A reader named Jill added: “I was sitting on my bed watching tv when my doorknob started rattling. My heart started racing because I’m home alone with my 1 year old and I didn’t know what it was. It was more nerve-wrecking because besides the sound of the doorknob, I heard nothing and FELT nothing. I live pretty close to john wayne airport so a lot of times when planes go by they rattle my windows and such so I tend to not notice the rattling anymore. But this was definitely weird and creeped me out pretty bad!”

Tracy Austin of Huntington Beach emailed to say, “We’re fairly used to a quake every so often, this one was very strange, our whole house rumbled. Felt like someone was shaking our front door. Our dogs definitely felt it coming.”

Note: Sciencedude is on jury duty in Santa Ana today. But I have temporary net access and I’m reading your emails. I am having trouble getting quick, clear info from Camp Pendleton about Tuesday’s high explosives work. We simply don’t know if explosives were going off in the mid-area of the base, behind the foothills, at the time of the mysterious shaking.


http://www.santacruzsentinel.com/localnews/ci_11835292
SANTA CRUZ - 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
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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."