What seemed to be a series of small earthquakes Thursday morning — rattling windows and setting off burglar alarms throughout Santa Barbara County and the Central Coast — were actually sonic disturbances caused by an Air Force F-22 operating at super-sonic speeds off the California Coast.
“What you felt is some kind of an air phase, not an earthquake,” said Steve R. Walter, a seismologist with the U.S. Geological Survey in Menlo Park. “It didn’t originate in the ground.”
The first shaking and rattling occurred at about 9:30 a.m., and was followed by four smaller occurrences shortly after 10 a.m., Walter said.
“The best guess as to the cause of these air events is that they are sonic booms caused by military jets traveling in excess of the speed of sound,” Walter said. “Because signals appear first on (seismic) stations to the south and later on those to the north, the jets were moving in a generally northerly direction, perhaps flying offshore of the coast, which might explain why a more sonic boom wasn’t reported.”
That explanation was later confirmed by Jan Kays, a spokesperson at Vandenberg Air Force Base near Lompoc, who said the sonic booms were caused by an F-22 jet out of Edwards Air Force Base.
“The aircraft was testing on the Western Range, which goes along the coast of California,” Kays said.
“Because of atmospheric conditions,” the traditional sonic booms associated with super-sonic jets were not heard, she said.
Officials at Edwards issued a statement saying the aircraft was flying 50 miles off the Vandenberg coast:
“Edwards conducts these types of operations year-round, but today’s atmosheric conditions allowed the boom to be heard and felt along the Central Coast.”
No quakes were recorded along the Central Coast Thursday morning, but the U.S. Geological Survey was reporting a 2.6-magnitude temblor with an epicenter about 2 miles from the Beaumont area near Riverside at 9:34 a.m.
But Walter said that hardly would have been felt in the Beaumont area, let alone along the Central Coast.
What occurred was “much like a sonic boom,” Walter said, adding that it’s surprising that no sound was heard.
Similar incidents have occurred in Northern California, Walter said, when the Navy has detonated ordnance offshore, but he does not recall it occurring in Southern California.
The shaking does show up on the USGS seismometers, Walter said.
Check back with Noozhawk for updates on this story.