The 'big bang' that was heard about 1am this morning had residents talking and people hypothesising on Facebook after reports of an "explosion" shaking homes in Winslow, Warrnambool and Terang.

This was allegedly accompanied by flashes of light in the sky that were variously described as being pink, orange and yellow, and seen as far away as Mortlake and Port Fairy.

Rumours grew and pranksters swooped: it was a tsunami heading towards Lady Bay; it was an earthquake measuring 5.3 on the Richter Scale that caused "extensive minor damage"; it was a sonic boom from a passing defence force jet.

The Standard has been able to confirm that it wasn't an earth tremor, with Geoscience Australia stating that no seismic activity had been recorded in the region.

Nearby volcano Tower Hill also appeared to be its usual dormant self.

Local police were unable to shed any light on the mystery, leaving the truth out there, but investigations are continuing.