What is a sonic boom? Why ‘earthquake’ was felt in parts of UK today, where it was heard - what it really was

Some areas of the UK were shaken by a sonic boom earlier today, with hundreds of people in the midlands of England reporting they felt it.

The tremor was reported at around midday on Saturday (4 March), with people taking to social media to explain they had felt the ‘mini-earthquake’.

What is a sonic boom?

A sonic boom is caused by an object travelling faster than the speed of sound.

Aircraft are one of the more common reasons for a sonic boom. When planes fly, they create sound waves whilst travelling through the air.

When travelling at a speed slower than the speed of sound, the sound waves are out in front of the plane.

If the aircraft travels faster than the speed of sound, therefore breaking the sound barrier, it will create a sonic boom as it flies past.

For the duration of the plane flying faster than the speed of sound, sonic boom will be dropped in its flight path.

This, according to the United States Air Force, can be likened to items being dropped from a moving car as it drives along a road.

If the noise heard in the north west of England was a sonic boom caused by a plane, the noise heard by residents would have been that of it flying past homes.

The ‘boom’ itself is the wake of the sound waves that the aircraft has created as it breaks the speed of sound.

What is the ‘Speed of Sound’?

The speed of sound often varies given the conditions of atmosphere and other surrounding factors, but in dry air at 20°C the speed of sound is roughly 768 mph.

What was the strongest sonic boom recorded?

The strongest sonic boom ever recorded was 144 pounds per square foot and it did not cause injury to the researchers who were exposed to it. The boom was produced by a F-4 flying just above the speed of sound at an altitude of 100 feet.

For some perspective, community exposure to sonic boom is below two pounds per square foot.

Are sonic booms illegal?

Sonic booms can cause damage to buildings and inflict damage to hearing if stood too close to the source.

In the 1970s, the damage and disruption that can be caused by sonic booms led to a ban.

It was made illegal for sonic booms to be created over land and especially densely populated areas.

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