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Sonic Event - 18 October 2012 16:15/16:30 BST (15:15/15:30 UTC)

SONIC EVENT: CORNWALL & DEVON 18 OCTOBER 2012 16:15/16:30 BST (15:15/15:30 UTC)

On the afternoon of 18 October 2012, from around 16:45 BST (15:45 UTC), the BGS began to receive information from the police in Newton Abbott and one resident in Cornwall, who reported that they felt what they had thought to have been an earthquake at sometime around 16:15 BST (15:15 UTC). Reports described a loud bang and windows and doors trembling.

Data from the BGS seismic networks in the region were examined and a signal consistent with a possible sonic origin was recorded at 15:15:56s UTC on station CCA (Carnmenellis, Cornwall). The reports received were also consistent with historical observations received for previous events with a sonic origin.  RAF Henlow were contacted and advised that there were no military jets on exercise in the area at the time.

A sonic boom is the sound associated with the shock waves created when an object, such as an aircraft, breaks the sound barrier. An aircraft travelling slower than the speed of sound (~760 mph) creates a series of audible pressure waves that spread out in front and behind it. These waves travel at the speed of sound. As the speed of the aircraft increases these waves get closer together and at the speed of sound they merge into a single shock wave that starts at the nose and ends at the tail of the aircraft.

The boom is created by the sudden increase in pressure at the nose and also as the pressure returns to normal at the tail as the aircraft passes. This can lead to a distinctive "double boom". The shock wave or boom continues to be generated for as long as the aircraft is supersonic, which is why they are typically observed along a long strip along the flight path of the aircraft.



The moment a sonic boom occurs. CLICK FOR A LARGER VERSION.