The largest earthquake in has felt for 25 years was caused by a maze of undetected faults lying beneath the country.
The magnitude 5.2 quake originated from an uncharted crack in the Earth’s crust 3.1 miles beneath Market Rasen, in
Lincolnshire , at four minutes before 1am yesterday.
People in Newcastle upon Tyne, , Yorkshire, the Midlands, Norfolk, London, Brighton and
South Wales felt the tremor, which displaced chimney pots and dislodged roof tiles.
One man in
Birmingham was taken to hospital with a broken pelvis after masonry crashed through the roof and landed on him.
The main ten-second tremor was the largest since 1984 when a magnitude 5.4 earthquake shook the
Lleyn
Peninsula in North Wales and was widely felt across .
The damage to homes and properties is expected to amount to more than £10 million, the Association of British Insurers said yesterday.
Another earthquake of a similar size might strike again in the next few weeks or months, Glenn Ford, a senior seismologist at the British Geological Survey, said. “There are lots of pre-existing fault lines in the , which is why we have these earthquakes,” he said. “They are random and they happen all over the country.
“Looking at the pattern, if someone asked me where there was a good chance where one would happen next, I would say in North Wales or northwest or
Hereford , but they are completely random.”
Edmund Booth, a chartered structural engineer, said: “The engineering community is suggesting that facilities such as bridges and hospitals should now be examined to see whether they are vulnerable to earthquakes.”
The area worst affected yesterday appeared to be Grimsby, in the northeast of
Lincolnshire , Humberside Fire and Rescue said.
Lincolnshire Police said that the force had received dozens of calls from residents but there were no reports of injuries in the county. Fire crews were called to 50 incidents and one fire.
Homeowners should be covered for any damage caused by yesterday’s quake. Earthquakes are considered a standard peril, as are storms and floods, and any structural damage to a property would be included in a standard buildings policy. However, damage to objects within the home would be covered only by a contents policy.
Any damage caused to vehicles by falling tiles and chimney pots would be covered if the owner had fully comprehensive car insurance.
Jason Harris, senior claims manager at Norwich Union, the ’s largest general insurer, said early yesterday: “We have seen claims coming in to our call centres overnight, but we expect further calls today as damage will be more obvious in daylight.
“At the moment these are reports of mainly minor damage, such as tiles off roofs, breakages inside the home and brick walls collapsing.”
Royal & Sun
Alliance said it had received about a hundred claims so far, mostly relating to damaged roofs and slates.
Seismologists said that yesterday’s quake could be blamed on a split in the Earth’s crust deep beneath the
Atlantic — the Mid-Atlantic Ridge — which is widening at a rate of 3cm (1¼in) a year.
is in the middle of the Eurasian tectonic plate, so it receives relatively few severe quakes, but stress generated at the plate boundary at the Mid-Atlantic Ridge is transferred to the interior of the plate through smaller cracks in the Earth’s surface.
The British Geological Survey said that the quake’s epicentre was likely to have come from an uncharted fault in rocks from the Ordovician Period, formed up to 490 million years ago. The two known faults in the area — the Askern-Spittal Fault and the Brigg Fault — have been discounted because they are too shallow.
Brian Baptie, a seismologist at the survey, said: “We’re in the middle of a plate. Some of the forces from the plate boundaries are transferred through the plate, and this causes stress to build up in places of weakness. When the stress is released you get an earthquake. It is the same with a chip in your car’s windscreen. When stress builds up, cracks begin there.”
Dr Baptie said that earthquakes in tended to consist of one main shock and a small number of minor aftershocks. One aftershock, magnitude 1.8, occurred at 2.46am yesterday.
Tim Pharaoh, a geologist at the survey, said that although people nearer the epicentre would suffer most, people further away would feel the effects more if their house was built on soft sediment rather than bedrock. “It’s like the biblical story — the man who built his house on rock is safer.”
has about 200 earthquakes each year; an eighth can be felt.
Buildings are deemed to be at risk from earthquakes above magnitude 5.
The Richter scale for measuring the intensity of earthquakes was superseded in 1993 by the more accurate moment magnitude scale.
Earthquakes in
4.7 1979 Carlisle (Felt as far as Glasgow)
5.1 1991 Bishop’s Castle (Felt throughout and )
5.3 1957 Derby
5.2 2008 Market Rasen
5.41984
Lleyn
Peninsula
6.1 1931 North Sea (Largest earthquake)
Source : www.timesonline.co.uk