SAN DIEGO COUNTY, CA. (THECOUNT) — A massive boom followed by shaking in San Diego, California Tuesday evening is being referred to as an “unknown event,” by the U.S. Geological Survey.

Countless people took to social media after hearing a large boom and feeling a sudden jolt on Tuesday evening.


An on-duty seismologist for the USGS later confirmed that there was no earthquake detected on sensors in San Diego County during the same time frame.

Whatever it was, it was noticed at around 5:10 p.m., with many who reported the event concentrated in the southern half of San Diego county, reports NBCSanDiego.

One Chula Vista resident told NBC 7 that said she heard and felt the vibration of the boom twice, about 10 seconds apart, and described the event as “like thunder, but without thunder.” She added that it “felt like something fell on my roof,” although there was “no shaking of our chandeliers, like with an earthquake.”

John McLees, also a Chula Vista resident, told NBC 7 he instantly recognized what he heard as a sonic boom. Meanwhile, Tomas Urtasun was puzzled when the back sliding doors to his South Park home shook loudly, as if something slammed into them, he told NBC 7.

In Clairemont, James Albert was out for a walk when he heard a “very low rumble that lasted about a second.” Albert said it didn’t sound like an earthquake but, rather, the sound of a large impact.

Other San Diegans reported similar experiences, everywhere from El Cajon to Jamul to Rancho San Diego to Del Cerro to Ocean Beach to Banker’s Hill. There were even some reports from as far north as Carlsbad.

Point Loma resident Sarah Dorsey, who was in her house watching TV at the time, said she felt it like a large truck passing by, with her windows rattling twice, about 5-10 seconds apart.

NBC 7 reached out to Navy and Marine officials in San Diego County but was unable to get confirmation regarding any operations at the time that may have to blame for the event.

A spokeswoman for Marine Corps Base Camp Pendleton confirmed the base regularly fires high explosive munitions and Marines were doing just that, according to their website. However, she added, it was not likely that munitions training would be of the magnitude to cause a sonic boom.


Geo quick facts: San Diego County, officially the County of San Diego, is a county in the southwestern corner of the state of California, in the United States. As of the 2010 census, the population was 3,095,313, making it California’s second-most populous county and the fifth-most populous in the United States – Wikipedia.