RESIDENTS from Highfields to Cambooya were a little shaken yesterday as they wondered what caused their homes and businesses to tremble.
Simply Beads owner Jeni Wilson said the glass doors of her Highfields shop suddenly started to shake about 2.30pm on Wednesday.
"There was a sort of dull thudding sound," Ms Wilson said.
"The blackboard started rocking backwards and forwards against the shop window."
Highfields resident David Zimmerle said he was at home when he noticed a similar sensation.
"I felt the windows shake and a fairly loud noise," Mr Zimmerle said.
"It is hard to explain what it was; it only last a few seconds."
Cambooya resident Susan Parton said she heard the noise over the sound of her television. "The whole house shook," she said.
People also noticed Wednesday's brief tremor in Torrington, Prince Henry Heights, Harlaxton and Plainland.
Centre for Earthquake Research in Australia director Dr Jack Rynn said no seismic activity had registered on measuring instruments in the Toowoomba area at the time.
Dr Rynn guessed the vibrations could have been caused by a low-flying aircraft or a quarry blast being amplified by low-level cloud cover.
"When a blast lets go the soundwaves bounce off the bottom of the cloud layer," Dr Rynn said.