Down the middle of the Atlantic Ocean runs a ridge, which is spreading outwards as molten rock wells up and creates new crust. This spreading pushes Britain slowly eastwards towards Europe and a similar activity from the direction of Africa pushes Britain northwards. If is also affected by lesser areas of tectonic expansion beneath the North Sea, Rhine Valley and Bay of Biscay. Finally, there is post-glacial uplift. Much of the north of the UK was covered by a thick layer of snow and ice until about 10,000 years ago, the weight of which pushed the rocks downwards. This ice has now gone and the rocks are slowly springing back into position, causing the occasional earthquake in the process. Although Britain has settled down geologically over the past few million years, there is still plenty of geological activity. The result is that there are 20-30 earthquakes a year. These are relatively small and the biggest British earthquake this century was centred on the Lleyn Peninsula in north Wales in July 1984. It was about 20 kilometres down and registered 5.4 on the Richter scale.
The Richter scale was invented in 1935 by Charles Richter. It is measured on an instrument called a seismograph and the scale is below :-
The Welsh Borders area suffers frequent minor earthquakes and many are caused by the Pontesford-Linley Fault. This is a geological fault line that runs from Pontesford to Linley and Clun. The following earthquakes have affected Shropshire :-
An earthquake centred on Shrewsbury (SJ4912). Recorded in British Geological Society records. No other details.
20th February 1247
Legend has it that Ippikin was a robber who lived with his gang in a cave under Ippikin’s Rock (SO568965) on Wenlock Edge. They were said to have been entombed there by an earthquake in the 13th Century which collapsed the cave entrance. There was a major earthquake in Wales on this date and this may be the one referred to.
An earthquake centred on Shrewsbury (SJ4912). Recorded in British Geological Society records. No other details.
27th May 1773
After days of heavy rain, a landslip occurred at a place called the Birches (SJ6303), located on the hillside above the River Severn between Buildwas and Coalbrookdale. More than 18 acres of land slid down the hillside, temporarily blocking the River Severn. There are reports of many vessels, having fallen over on their sides in the drained river bed downstream, being lost when the river finally found a new course past the blockage. Great chasms 30ft deep appeared in the hillside above, with pillars of earth left standing within the chasms, the ground below having moved a considerable distance. It is believed that the landslip was caused by a local earthquake. There is a plan of the landslip, surveyed and drawn by George Young :-
The plan details the change in the course of the River Severn, showing the alignment of ‘The Old Course of the Severn’ and ‘The Present New Channel.’ Also marked is the ‘Former Situation of the Turnpike Road’, a house, garden and hedge which had been moved in the process, the remains of a barn which had been destroyed and ended up in the bottom of one of the chasms and Birches Brook. Marked on the plan were the many large breaches in the land on the north and east sides of the river, particularly in the Birches Coppice. A number of written accounts survive, including several personal experiences, detailing the impact of the earthquake. The main descriptive account is that of Reverend John Fletcher, a minister from Madeley. He preached a sermon the following day on the ruins, to more than 1,000 spectators. In it, he made parallels between the phenomenon at Buildwas with Biblical stories, emphasising the wider religious context. An extract from Fletcher’s account describes how the earthquake occurred and similarities with the effects of other extreme weather events.
“The Birches saw a momentary representation of a partial chaos. Then Nature seemed to have forgotten her laws. The opening earth swallowed in a gliding barn. Trees commenced itinerant, those that were at a distance from the river, advanced towards it, while the submerged oak broke out of its watery confinement, and by rising many feet recovered a place on dry land. The solid road was swept away, as its dust had been in a stormy day. Then probably the rocky bottom of the Severn emerged, pushing towards heaven astonished shoals of fishes and hogsheads of water innumerable. The wood like an embattled body of vegetable combatants, stormed the bed of the overflowing river and triumphantly waved its green colours over the recoiling flood. Fields became moveable, nay they fled when none pursued and, as they fled, they rent the green carpets that covered them in a thousand pieces. In a word, dry land exhibited the dreadful appearance of a sea-storm. Solid earth, as if it had acquired the fluidity of water, tossed herself into massy waves, which rose or sunk at the back of him who raised the tempest. And, what is most astonishing, the stupendous hollows of one of those waves, ran for near a quarter of a mile through rocks and stony soil, with as much ease as if dry earth, stones, and rocks, had been a part of the liquid element.”
Fletcher’s account includes several personal recollections. Samuel Cookson, a farmer who lived half a mile below the Birches on the side of the river where the landslip occurred, recalled that he had been frightened by ‘a sudden gust of wind which beat against the windows as if a great quantity of hail show had been thrown with violence at them.’ People living in a house above Buildwas Bridge, which was more than a mile away from ‘the Birches’ but on the same side of the river, recalled that their house shook violently so they left the house taking goods and possessions with them. That night, the house and adjoining buildings were shaken again and demolished. The earthquake disrupted the navigation of the river, which at that time was an important inland transport route for boats carrying goods between Coalbrookdale and Bristol. A letter published in the London Evening News records the disruption to navigation which the earthquake or landslip caused, although this was resolved as the river formed a new channel with sufficient depth for a vessel laden with 30 tons of cargo to navigate. It also gave the cause of the earthquake as being the result of the ‘late rains’ which, ‘getting down to the rock on which this bank stood, loosened the foundation, and its weight carried it into the river.’
“On Thursday arrived here a barge from Shrewsbury which brings an account that the Severn has already formed a channel for itself through the meadow into which it was turned by the slip of the bank mentioned lately. The people on board this barge say they were the first that ventured through the new cut and that they had sufficient depth of water, though they were loaded with 40 tons of goods. The spot where this remarkable event happened is thus described :- The Birches was a considerable eminence that overlooked the Severn and the meadows on the opposite side. It lay 400 yards below Buildwas Bridge, which is about 10 miles from Shrewsbury. The slip is supposed to have bene caused by the late rains, which, getting down to the rock on which this bank stood, loosened the foundation and its weight carried it into the river. The depth of the earth that moved appears to be 20 yards and the quantity of land 20 acres, or rather more. The turnpike road is removed several yards and turned up edgeways”.
Captain Moseley of Buildwas Park wrote in his notes on the parish history of Buildwas, “Landslip on 27th May 1773 some 23 acres of land (including parts of the Birches Coppice and a cottage on the steep northern bank of the river, close to the boundary between the parishes of Buildwas and Madeley, slipped badly down the hill side, destroying the main road and altering the course of the Severn. ‘Birches Coppice’ and the site of ‘The Slip’ is still marked on the modern Ordnance Survey map and even today the Ironbridge Gorge continues to experience landslips requiring remedial work to maintain the stability of the roads and buildings in the area.
22nd June 1773
It was claimed that an earthquake had been felt at Hinnington (SJ7404) near Shifnal “… tho’ the earth did not open there, as it did at the Birches”. There are, however, no official records confirming that an earthquake occurred on that day.
15th August 1926
Earthquake at Ludlow (SO5174) at a depth of 27 kilometres, measuring 4.8 on the Richter scale. No other details.
Wikipedia claims that there was an earthquake at Shrewsbury (SJ4912) but there is no other official record.
2nd April 1990
Earthquake at Clun (SO3080) at a depth of 14 kilometres, measuring 5.2 on the Richter scale. It was felt by people as far away as the Republic of Ireland to the west, the city of Newcastle upon Tyne to the north-east, the county of Kent to the south-east and the county of Cornwall to the south-west. In Shrewsbury, there was damage to masonry, with a number of chimney stacks being broken off from roofs and collapsing partially or completely into gardens and streets. Some others were knocked askew. Several of the worst affected buildings, including shops, were evacuated. At least 50 properties were reported as requiring emergency attention within the 24 hours immediately following the event. There was also damage to ornamental features such as crosses and gargoyles, built into the masonry of some of Shrewsbury's medieval churches and Clun Castle. Electrical power was lost from areas served by some substations situated approximately 30 kilometres from the epicentre, after the earthquake caused transformers at the substations to trip offline. Residents of the worst affected areas, including parts of Shrewsbury, reported lateral shaking and swaying to the walls of their houses at the height of the tremor, which was preceded and then accompanied by a rumbling noise that gained strength over a period of 15-30 seconds before reaching and sustaining peak intensity during the most severe shaking. Finally, the movement and accompanying sound tailed off much more rapidly than it had first built up, stopping altogether within just a few seconds from the peak activity. Damage to buildings was also reported in Wrexham, and some minor damage as far north as Liverpool and Manchester. No serious injuries were reported.
6th March 1996
Earthquake recorded 11 kilometres below Harmer Hill (SJ4922), measuring 3.4 on the Richter scale. It was felt in Shrewsbury and lasted for a couple of minutes. It brought some worried residents out of their homes and into the street in their nightclothes but the energy released at the surface was so slight that, at worst, only a few roof tiles toppled and some cracks appeared in walls.
1st June 2012
Earthquake recorded 14 kilometres below Cleestanton (SO5779), measuring 2.5 on the Richter scale. It caused houses to shake for miles around and made a sound resembling an explosion. Others said they heard a rumble of thunder around the time the quake struck. Patricia Clanzy-Hodge of Orleton said “I was upstairs in the main bedroom when I heard a noise – it sounded like an explosion outside. The whole house seemed to rattle for a few seconds”. Cheryl Jewell of the Brown Clee area thought at first it was thunder in the air. She said “I heard a rumble and initially thought it was thunder. Then I felt myself shake while leaning and looking out my window”. Andrew Noakes of Clee St Margaret said the tremor "sounded like something being dragged on outside on the pathway, or like a truck going past. I was having lunch when I thought I heard something. The sound only went on for a few seconds and then it stopped. There was no shaking cutlery or furniture." David Wright said that it "sounded like a lorry pulling away quickly from the traffic lights. There was a strange feeling as birds actually stopped singing for a while”. Yet Tracey Baylis of Cleeton Stanton said that they hadn’t felt a thing despite being close to the earthquake’s epicentre. She said “We were in the cottage at the time with the dogs and did not feel anything. I would have thought the dogs might have noticed”.
29th April 2013
Earthquake recorded 3 kilometres below a point 10 kilometres north-west of Telford, measuring 1.0 on the Richter scale. This was only a small earthquake and caused no damage or injuries, in fact hardly anyone felt it at all.
9th January 2014
Earthquake recorded 15 kilometres below Knighton (SO2972), measuring 1.3 on the Richter scale. It was too small for residents to notice anything but the power went off a few times as substations tripped.
28th January 2015
An earthquake at Cottesmore (SK9013) in Rutland, measuring 3.8 on the Richter scale, was felt in Market Drayton and Telford. There was no damage caused and many people didn’t even feel it.