Seismologist answers readers’ questions about earthquakes in Leighton-Linslade

Families felt their homes shake at around 9.30am on September 22 as the first tremor startled residents with a magnitude of 3.0.

And just when LBO land began to think that three earthquakes in two weeks was impressive, a fourth, smaller tremor was reported at 1.39pm that afternoon, with a magnitude of 2.1.

But why do the quakes keep happening?

The LBO contacted a seismologist at the British Geological Survey to ask questions from readers, such as ‘Is Leighton-Linslade on a fault line?’ and ‘Have some of the earthquakes been aftershocks?’

Richard Luckett, from the BGS, said: “There are faults everywhere in the crust and all earthquakes occur when a fault ruptures. In general, we know nothing about faults many kilometres down until an earthquake happens.

“An aftershock is a name that we use to describe an earthquake that happens after a larger earthquake.

“All four events were earthquakes and we would call the later ones aftershocks because they were smaller.

“The later earthquakes will certainly have been the result of stress changes caused by the first earthquake.”

Other residents wondered if fracking, sink holes or work on HS2 could be the cause.

Richard added: “Fracking could not be the cause because there hasn’t been any anywhere near and there is no reason to think that HS2 has anything to do with the earthquakes.

“I’m afraid I know nothing about sink holes.”

The first two earthquakes were on September 8 and 13, with magnitudes of 3.5 and 2.1 respectively. But will there be be a fifth?

Richard said: “There is a possibility that there will be more earthquakes of this sort of magnitude. There have been several cases in the UK of quite long sequences of small earthquakes. The most recent example is the earthquakes in Surrey.

“A lot of the noise from an earthquake is caused by buildings moving. The house shakes and one part of the house moving against another makes the noise.”

Speaking about the fourth tremor, one resident posted on the LBO’s Facebook page to say: “I felt it at lunch time - this time only the windows rattled, no wall rumbling so much fainter.”

However, the earlier tremor (earthquake number three) had caused much more alarm.

Comments on the LBO’s Facebook page included: “It felt like my neighbours upstairs had dropped their oven, fridge freezer and washing machine on the kitchen floor right above my head!” and “I was sitting on the garden bench and I thought someone had sat down beside me, that’s how it was in Linslade.”

Another lady said: “My house shook again and there were loud bangs. Three times in two weeks is worrying.

“There’s more to this than we are aware of.”

Both these earthquakes had a depth of 10km.