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The U.S. Air Force retracts an earlier statement and says that it was responsible for breaking the sound barrier over Salt Lake City.
SALT LAKE CITY -- The U.S. Air Force took responsibility Wednesday for a set of mysterious booms that had scientists stumped as they pondered the origin of the widely reported vibrations across northern Utah.
Seismologists said the booms weren't an earthquake. The Air Force at first said its aircraft didn't break the sound barrier. Aerospace company ATK said it wasn't testing any rockets. And asteroid and meteorite watchers had nothing to report.
It had to be something.
"It was like my walls were shaking," said Catherine Whidden of the University of Utah Seismograph Stations, who said instruments recorded back-to-back booms around 9 p.m. Tuesday.
She believes the low-frequency rumble originated in the atmosphere and not from beneath the ground.
That shifted attention to Hill Air Force Base, about 20 miles north of Salt Lake City, which flies squadrons of sound-busting F-16s.
Hill officials blamed the 2nd Bomb Wing of Barksdale Air Force in Louisiana, which was using B-52s to drop bombs in Utah's west desert.
"We believe conditions were perfect for the noise to travel a long distance," Air Force spokesman George Jozens said Wednesday.
The B-52s will be dropping bombs again Wednesday night across the 2,600-square-mile Utah Test and Training Range.
With low cloud cover and dense fog covering much of northern Utah, the Air Force believes conditions were ripe for bomb noise to "carry, ricochet and even be amplified" over some 100 miles toward Salt Lake City.
Meteorologists heard what sounded like thunder and felt the walls of their office shake at the National Weather Service office in Salt Lake City. But the weather was calm.
Before the Air Force took responsibility, science buff Larry Park speculated the vibrations were "earthquake booms" originating inside the Earth.
Park has gained notoriety for trying to forecast earthquakes. Days after a tsunami that swept across the Indian Ocean in 2004, he panicked tens of thousands of people with an urgent warning to authorities that another earthquake could roil the ocean.
It didn't happen, and India's science minister scolded him.
"The booms going on near Salt Lake City are acoustic or sonic types of signals that are new to the seismological community," said Park, a Hillsboro, Ore., electrical engineer who uses instruments that he says measure the elasticity of the Earth's crust.
Whidden, however, said mainstream science doesn't recognize "earthquake booms" as a real phenomenon.
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