On the afternoon of 12 January 2012, from around 15:20 UTC, the BGS began to receive information from the media, the police and many residents in predominantly coastal towns and villages in the southern Scottish Borders, Northumberland and Tyne & Wear, who reported that they felt what many had thought to have been an earthquake at sometime around 15:15 UTC.
Data from the BGS seismic networks in the region were examined and signals consistent with a possible sonic origin were recorded at around 15:13/15:14 UTC on several stations. The observations received from the pubic are similar to those which have been received previously for sonic booms. The RAF were contacted and advised that there were two military jets on exercise in the area at the time. Several members of the public have also reported seeing two military planes flying in the area at the time of the occurrence. RAF Boulmer have since confirmed that a single Tornado GR4 fighter aircraft had completed a pre-planned supersonic sortie to RAF Marham in Norfolk.
The extent of the effects of the sonic boom were felt over a distance of approximately 115 km, stretching from Eyemouth, Scottish Borders, to just north of Sunderland, Tyne and Wear. The locations furthest inland from where reports were received were Duns, Wooler and Bedlington. Reports described "roof rattled, floor bounced", "the whole house shook violently for a couple of seconds", "very heavy rumble, as if an absolutely massive lorry had passed right next to me", "the front door shook and the letterbox flapped", "door rattled on its hinges and floorboards flexed causing my chair to move whilst I was in it " and "vibration lasted for around 5 seconds with a rumbling noise".
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.