Mystery surrounds shaking felt Tuesday night from at least Weber County to Salt Lake City, accompanied by a rumbling noise.
Dispatchers received several calls about 9 p.m. from people who felt the rumble, but an explanation for it remained elusive. There was no earthquake in Utah on Tuesday night, said Jim Pechmann, a seismologist at University of Utah Seismograph Stations, but research instruments did pick up two sonic waves about 9 p.m.
A plane breaking the sound barrier could cause such a wave, as could an explosion though quarries cannot legally blast at night, Pechmann said. Wherever it originated, the inversion can cause a sonic wave to travel farther than it normally would, he added.
But Davis County dispatchers report that Hill Air Force Base was not responsible, and ATK spokeswoman Trina Patterson confirmed that the company also could not have caused the shaking, since they were not running tests at their site in Box Elder County on Tuesday night. Even if it were, ATK's biggest booster could not be felt from several counties away, Patterson added.
Patterson was at her North Salt Lake home at the time, and she also felt the mysterious quake. The pictures on her wall shook, and she also heard a low, deep rumbling noise. She then felt a second, weaker rumble a short time later.
"It sounded like thunder," said Pete Wilensky, lead forecaster for the National Weather Service in Salt Lake City. He and his colleague also felt the walls of their office shake, though they could tell it was not coming from the floor. There is a lot of speculation about what it could have been rockets, a meteor but the weather service could not identify the source of the disturbance either, Wilensky said.
Also in Salt Lake City, Jesse Fruhwirth, who lives near 1300 South and 900 East, noticed his door "quite noticeably" rattle once, but heard no noise.
The U.'s seismograph center plans to analyze their data further on Wednesday morning to see if they can shine any light on what the mystery shake was.