Did you feel the earth move under your feet last week? We certainly did….. and after a quick investigation of possible causes, we came to the conclusion that the tremors we felt were all down to the earthquake in Wales that was felt across Gwynedd and the Llyn Peninsula on Tuesday.

According to the British Geological Survey (the organisation that measure and record earth tremors in the UK) there are hundreds of earthquakes across the UK each year, although luckily for us the vast majority of them are too faint and minor to be felt by humans. And even the ones that are felt are rarely strong enough to do any damage.

The reason for earthquakes in the UK isn’t really known but is thought to be because of the movement of the tectonic plates that sit deep under the surface of the earth, or a release of pressure through the layers of the earth’s crust. The geology and climate of Wales mean that, thankfully, we never suffer the kind of destruction and devastation that has besieged Nepal after the tragic earthquake struck earlier this month. But, the area around the Llyn Peninsula and Anglesey seems to be an epicenter for numerous small earthquakes each year, although it’s not really known why.

Earthquakes are measured on the Richter Magnitude Scale, which, according to Wikipedia “defines magnitude as the logarithm of the ratio of the amplitude of the seismic waves to an arbitrary, minor amplitude.” Earthquakes are measured with a seismometer.

As far back as the 13th century, earthquakes have been recorded in Wales…. and here are some of the most powerful. How many do you remember?

• On the 20th February 1247, an earthquake measuring 5.5 on the richter scale was said to hit south west Wales with some damage to St Davids Cathedral reported.
• In July 1534 an earthquake of 4.5 hit North Wales and was felt in Ireland.
• In October 1690, a huge earthquake of 5.2 was recorded in Caernarfon.
• In August 1757 an earthquake of 3.5 was recorded in Holyhead, on Anglesey.
• And again in April 1773, a quake measuring 3.7 was felt in Caernarfon.
• Caernarfon was hit again in 1827 but this time it was a small tremor of just 2.8
• And slightly higher in August 1842 when a quake of 3.0 was measured in Caernarfon.
• In November 1852 one of the largest earthquakes in Wales for many years was recorded, again in Caernarfon and measured 5.3.
• June 1903 and Caernarfon was shaken by another quake, this time measuring 4.9.
• In July 1984 the Llyn Peninsula was the epicenter of an earthquake measuring 5.4; it’s effects were felt across North and Mid Wales with many people reporting feeling tremors
• 26th May 2015 was the latest quake to be felt in North Wales, but measured just 3.0

Yet despite this seemingly long list of minor earthquakes, some of which have measured over 4 and 5 on the Richter scale, we’ve been fortunate here in Wales to never have recorded a serious casualty or loss of life resulting from earthquakes. So for now, we can sit back and enjoy the novelty of a little earth shaking beneath us, and thank our lucky stars that this strange natural phenomena is not more serious for us.

The Llyn Peninsula has been an epicenter for numerous earthquakes. Image by Charlieb4u2 via Wikimedia Commons