Orange county map
© UnknownBizarre: The USGS reported a 2.2 quake at 9:30 a.m. Tuesday that supposedly shook much of Orange County. But we didn't receive any calls or emails then. The emails didn't start until 9:15 p.m. tonight, almost 12 hours later -- even though much of tonight's shaking came from areas depicted in this map. Seismologist Bob Dollar called the situation "mysterious."
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.

And, in an extraordinary odd coincidence, a similar event occurred at 9:15 a.m. today (Wednesday) in Central California. Click here to read story.

"This morning Kate Hutton (of Caltech) reviewed seismograms from the event last night in Orange County," Dollar said in an email. "These data are consistent with a sonic event coming onshore near Dana Point and traveling northward inland.

"The energy traveled 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.