San Diego: Mystery Boom That Shook House Baffles Experts

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A bus on the Mexico side of the US-Mexico border makes its way up a winding dirt hill in Tijuana beside a fence separating the two countries near where prototypes of US President Donald Trump's proposed border wall are standing on November 1 in San Diego. The concrete and steel structures, erected in a remote area in San Diego, will be tested for 30 to 60 days to determine which design meets the needs to secure the border, US Customs and Border Patrol Protection said in a statement. Authorities said that in considering the mockups -- built by six companies from across the United States -- they will evaluate a number of characteristics including anti-breaching, anti-climbing and anti-digging capabilities. Frederic J. Brown/AFP/Getty Images

A mysterious loud sound and rattling shook San Diego on Thursday morning, according to NBC 7 . Those who experienced the shaking thought it may have been an earthquake, but local news agencies report otherwise.

Rather, it may have been a meteorological event caused by a clash of warm and cool bodies of air, the Center for Scientific Research and Higher Education in Ensenada told NBC 7.

#Breaking: Reports of a "boom" and shaking from different areas of the county Share your experience with us

— NBC 7 San Diego (@nbcsandiego) November 2, 2017

At least one expert agrees that the weather may be to blame for the startling noise.

"You can get enough contrast between colder air and warmer air for example that will almost act like a reflecting board," Pat Abbott, a professor emeritus of geology at San Diego State University, told Fox 5. "So some sound can go up hit some other surface and go over an area like an unexpected area."

Abbott also noted that the sound probably originated miles away from San Diego.

"It may have been a quarry blast in another county, for example something like that got reflected towards us," he said.

San Diegans report hearing "boom," houses rattled. Did you hear or feel it?

— FOX 5 San Diego (@fox5sandiego) November 2, 2017

Local officials are reportedly investigating the incident but have yet to determine a cause.

Residents took to social media shortly after the mysterious event shook the ground around 11 a.m. local time and questioned whether it was related to military operations at Camp Pendleton, a U.S. Marine Corps training base in the county. However, that possibility was ruled out.

"There is routine mortar training being conducted on the base, but it is highly unlikely that an impact would be heard and felt all the way in San Diego," Cpl. Shellie Hall told the San Diego Patch.

A resident in Bonita, which is located in Southern San Diego, told CBS 8 that the event rattled her house and some of her belongings. Those living and working in other parts of the county reported a similar experience.

Mysterious boom, rumbling reported across San Diego

— CBS News 8 (@CBS8) November 3, 2017

"It felt like a big semi-truck passing the building where I work," Bryan Gonzalez, who was in Chula Vista at the time, told the San Diego Patch. "It shook the racks, and I thought it was an earthquake."

But, the U.S. Geological Survey—the federal weather-monitoring agency—didn't flag any earthquake activity in the area.

Although it's unconfirmed, one resident believes he has the answer to the mystery. It was a sonic boom caused by a plane, Chad Morris, who previously served on board the USS Nimitz, said.

"You could tell it was an aircraft. Just the way that the sound echoed across the sky," Morris, who heard the noise in Lemon Grove, told CBS 8.

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