West, Ian M. 2017. Earthquakes of the of the south of England. http://www.southampton.ac.uk/~imw/Earthquakes-South-of-England.htm. Version: 7th April 2017.

Earthquakes of the South of England - Introduction

by: Ian West
Romsey, Hampshire,

and Visiting Scientist at
Faculty of Natural and Environmental Sciences,
Southampton University
Website hosted by courtesy of iSolutions, Southampton University
Website archived at the British Library.
Aerial photographs by courtesy of The Channel Coastal Observatory .

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INTRODUCTION:

Earthquake Magnitude - BGS

This webpage is only concerned with the earthquakes of southern England. See also the notable published works which cover the subject, such as Mallet (1858) and Davison (1924). See also British Geological Survey publications and webpages such as: What is Earthquake Magnitude? (British Geological Survey, BGS).

The earthquake magnitude is measured from the earthquake displacement or magnitude as seen on a seismometer. There has to be a correction for distance of the seismometer from the focus of the earthquake, and certain types of waves are used for measurement. The technicalities are not discussed here. The BGS uses the Richter Local Magnitude, abreviated to ML for British earthquakes. Because of the use of a logorithic scale, a magnitude 6 ML is 30 times larger than a magnitude 5 ML. See the BGS webpage for more details.

From a practical point of view, magnitude 4 ML earthquakes in southern England rattle houses and might damage chimneys but are not devastating. 5 ML would be very rare. The earthquakes of this region are rarely worse than 4 ML, but they have been exceptions. Southern England is not a location of major plate tectonics and it only shows some limited activity in terms of fault movement at the present time.

Earthquakes also tend to occur in the English Channel or La Manche near the Straits of Dover and thus can affect Kent. They can also occur further west. A notable area for mostly minor earthquakes is the region of Chichester (and adjacent Portsmouth) and the emphasis is on this region because the associated webpages are on the Wessex Coast.

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INTRODUCTION:

Earthquake Magnitude - Davison Scheme

Davison (1924) used his own (unofficial) scheme for earthquake intensities in England. Since Davison's records are used here, it is necessary to explain his scheme.

[section to be added]

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LOCALITIES:

CHICHESTER, PORTSMOUTH AND ISLE OF WIGHT REGION
(with some earthquakes affecting this area but also throughout England etc. also listed)

Chichester Cathedral spires, Chichester, Sussex, June 2015

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Chichester, West Sussex, and south of England earthquake centre, a street scene, June 2015

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Chichester, and adjacent region, is a major locality for earthquakes in the south of England (rarely dangerous). With principal earthquakes every 25 years and minor ones in between (Davison, 1924). There has been one, known, very probable case of oil and gas escape from the local oilfields of the Chichester area (see below).

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In southern England the Chichester and adjacent area is notable for the frequency of earthquakes. They are usually small events of 3 to 4 magnitude, but there are occasional more severe quakes up to very strong, intensity 7 (1750, Chichester and affecting Brighton to Bridport). There is even the possibility of an historic Chichester earthquake causing more than one fatality. Generally the earthquakes did little more than made a noise and shook the ground. Occasionally they probably broke chimneys and caused damaging to weakly-constructed buildings. There seems to be no record of a severe earthquake though in the 500 years or so of reports, except perhaps one in 1275, if the epicentre really was at Chichester. With the Dover region, it is one of the main earthquake localities on the south coast of England. The earthquakes have been attributed to minor re-activation on a deep north-south strike-slip fault, which is the eastern termination of the Isle of Wight type of structures, and may be linked southward to the Massif Central of France. This is reasonable but details are not yet clear, however. Damage from these relatively minor earthquakes at Chichester has not been severe. Of course, a rather larger earthquake here is not impossible. Chichester Cathedral has been present for a short while in geological terms, only about 1000 years, but its survival supports the view that major earthquakes are probably very rare here. .

[Further note re Chichester Earthquakes "In the autumn of 1833, a centre [earthquake centre] near Chichester, which had been in action from time to time for nearly two centuries, gave rise to a series of moderately strong earthquakes that continued for nearly two years. These earthquakes were studied by an unofficial committee in Chichester, of which Mr. J.P. Gruggen was secretary. The report which he drew up was communicated to the Royal Society, but only a very brief summary was published [Royal Society Proceedings, vol. 3, 1837. The original report is preserved in the Archives of the Royal Society, but there are extracts from it in Davison, 1924]. Of considerable value in itself, it is interesting as the first report of a committee instituted for the study of British earthquakes."]

The British Geological Survey, BGS, has undertaken thorough work on British earthquakes. It has commented briefly regarding the Chichester area as follows, in a webpage - Seismicity and Earthquake Hazard in the UK.
"There are also important centres of activity near Chichester and Dover. The former produced a swarm-like series of small, high-intensity earthquakes in the 1830s and was active again in 1963 and 1970."

See the earthquake publications by BGS and in particular the papers of Musson (of the British Geological Survey).

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SOUTH OF ENGLAND EARTHQUAKES
- A GENERAL LISTING, WITH PARTICULAR REFERENCE TO CHICHESTER EARTHQUAKES

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Note earthquakes, mostly minor, occur quite commonly in the Chichester region (but also near Dover and Canterbury). Some of these are the effects of movements in the English Channel to the south. The listing below is an attempt to collate some data with regard to Chichester, but also to see these local earthquakes in a broader perspective. Thus other earthquakes that have affected southern England are included. The list is not comprehensive. South coast tsunamis are also discussed.

There are minor earthquakes at Chichester, and also the adjacent Portsmouth, Havant and Isle of Wight areas at fairly frequent intervals. They occur about every couple of years and cause little more than a rattle of ornaments in a house. Very rarely, perhaps once in 500 years or more there is a serious earthquake here which causes major damage. Chichester is situated near a north-south fault system deep beneath the English Channel. Details of this will be discussed further down in this account [to be inserted later]. A record of known earthquakes in the Chichester area, with some notes on the effects, is given below.
Intensities are given from British Geological Survey figures in some cases. These are referred to in the style of - "magnitude 4.5". Some are listed by Davison are according to his own scheme, and do not relate to a modern system. They are listed here as "Davison intensity 5" and should not be confused with a modern magnitude system. Wherever possible use the BGS magnitude system.

("In the autumn of 1833, a centre near Chichester, which had been in action from time to time for nearly two centuries, gave rise to a series of moderately strong earthquakes that continued for near two years. These earthquakes were studied by an unofficial committee in Chichester, of which Mr. J.P. Gruggen was secretary. The report which he drew up was communicated to the Royal Society, but only a very brief summary was published (Roy. Soc. Proc., vol. 3., p. 338). Of considerable value in itself, it is interesting as the first report of a committee instituted for the study of British earthquakes." (Davison, 1924).)

LIST

1076, March 26th "throughout all England. Accompanied by subterranean noise." Matthew of Westminster, lib. ii, p. 6. (more shocks on April 6th and April 22nd). (Mallet, 1858)

1081, March 27th 1081, first hour of the night. Throughout England, and elsewhere. (Mallet, 1858)

1089, Aug. 11, 3rd hour of the night. Throughout all England. "Houses were seen to leap upwards and return to their position. Simeon Dumelmensis. (Mallet, 1858)

1099. England. (no details). Mallet, 1858.

[1108, (not an earthquake) original Chichester Cathedral building history. Cathedral partially destroyed by fire in 1120, then restored, then destroyed by fire in 1187]

1134. October 1st, middle of the night. A tsunami hit the coasts of England and the Netherlands. (it not known whether it affected the English Channel coasts). No land shock was felt. "The sea rose suddenly with such violence as to inundate the country, and retired to its usual level as suddenly." Mallet, 1858.

1155, Mont St. Michel, France. Before the rising of the sun. (There is no information that it was detected in England0#)

1158, London and other parts of England. The River Thames dried up so that it could be passed dryshod. Mallet, 1858. (not known whether this affected the south coast).

1180, about Sept. 29th. Two or three shocks. No details. Location not known. Mallet, 1858.

1186. middle of September. almost universal in Europe. Especially in England, Calabria and Sicily. In England houses were thrown down, and in Calabria and Sicily many towns ruined. Mallet, 1858.

1274. December 5th. Throughout England. "A comet and a fiery dragon". [i.e. presumably a meteorite with a tail]. "Accompanied by thunder and lightning." In Pay de Galles (France) - Accompanied by a rain of blood [i.e. red rain]. [meteorites can produce thunder and the fireball may be mistaken for lightning]

1275 - Possible Chichester Epicentre?: Glastonbury Tor Earthquake . (Destruction of St. Michael's on the Mount, the church on Glastonbury Tor). Unconfirmed as a Chichester earthquake but quite possible. See comment (p. 322) in:
Musson (2007).
"In fact what was destroyed was St. Michael's on the Mount which is the name of the church on Glastonbury Tor. But putting an epicentre in Somerset (as in Ambraseys and Melville, 1983) is unlikely to be correct. Damage to one very anomalous construction perched on a steep hill is not indicative that the earthquake source was nearby. Musson (1994) suggested a possible epicentre near Chichester on the basis of what is stated concerning places where the earthquake was felt. The annals of Osney (Luard, 1868-9) state that people were killed by this earthquake - this is the only contemporaneous record that refers to death in a medieval British earthquake."

1426. September 29th, Between 1 and 2 am. "The shocks lasted for two hours. Preceded by a dreadful tempest.". Mallet, 1858.

[1551. May 25th. (Not Chichester area). Rygate [Reigate}, Croydon and Darkin [Dorking]in Surrey. Especially Darkin. Kitchen utensils and other moveables were thrown from their places. Strype's Memoir. Eccles, vol. ii., p. 272. Mallet, 1858. This is the northern edge of the Weald. It was probably reactivation of a northern Weald boundary fault.]

1553 - Southsea Earthquake. Cat. No. 48. Reference: R. Fabyan, p. 711. Davison. An earthquake felt at different places, but especially at Southsea (seafront region south to Portsmouth), between Easter and Whitsuntide (Davison, 1924).

[1574, February 26th, between 5 and 6 pm. York, Worchester, Gloucester, Bristol, Hereford, and the neighbouring counties. Very violent. At Tewkesbury and some other places plates and books were thrown from their places. The who were on their knees in the chapel of Norton were almost all thrown down. A part of Ruthin Castle was ruined and the bell in the market town of Denbigh sounded two strokes. Stow's Chronicle, p. 679; Coll. Acad., Rev. du Globe. In Mallet (1858) p.62.

[1580. 6th April. But Dover Sraits Earthquake. Estimate 5.9. Netogram Com. List of Earthquakes.;
6pm April 6th 1580. Throughout England, especially at London, Dover, and the whole of Kent. Also in France at Boulogne, Calais, Paris, etc.; in Belgium at Brussels, Malines, Cologne etc. in Zealand and Holland. Most violent in England. At London and environs the earthquake lasted about one minute. Two other lighter shocks were felt throughout Kent, namely at 9 and 11 pm.
At Sandwich the sea was so much agitated that the vessels in the harbour were dashed against one another. The same happened at Dover. The great bells of Winchester and other places were made to sound. Portions of several buildings and many chimneys were thrown down in London. The heavens were serene and the air quite tranquil. (From Mallet, 1858, p.63, who gives references)}

[Dover Straits earthquake (1580) - Wikipedia Main article: 1580 Dover Straits earthquake
On 6 April 1580, a 5.8 magnitude earthquake occurred with its epicentre on the sea bed close to Calais. Giant waves were reported at the time and hundreds of people were killed when ships were sunk by the waves and the low-lying coastal land around Calais was inundated by the sea. In Dover, part of the chalk cliff collapsed, taking with it part of Dover Castle. A contemporary French account states “in the city of Calais such a horrible and terrible earthquake came to pass that a great part of the houses fell, and even the sea overflowed into the city and did ruin and drown a great number of houses, and numerous persons perished, and a great multitude of beasts lost which were at pasture outside this city.” In recent years, it has been suggested that these waves were a tsunami and not seiches. It is unlikely that the earthquake alone was strong enough to rupture the sea bed to trigger a tsunami, but it appears to have been sufficiently powerful to have caused an undersea landslide that was capable of generating a tsunami...]

[1580. May 1st. County of Kent, especially Ashford. Also in the Netherlands as far as Cologne. Shocks - very considerable. Ref. Camden. referred to by Mallet, 1858, p. 63]

1638. Chichester Major Earthquake causing great damage (and apparently releasing gases). 1638, end of the year. Several shocks causing great damage at Chichester. Cat. No. 61. (Mallet, 1852). (Davison, 1924). Mallet, (1852) recorded:
"An earthquake at Chichester in Sussex, which did great damage. It was accompanied by the smell of pitch and sulphur. The atmosphere was obscured "as if by a cloud."
Some details are in The Sussex County Magazine, Volume 5. See Arthur Beckett. T.R. Beckett., 1931 - Periodicals. See also the webpage by Chris Chatfield: The Gallery of Natural Phenomena: The earth, the sea, the sky - and beyond. Chris Chatfield's Cabinet of Curiosities. Author - christopherchatfield@gmail.com
Comment: Methane and hydrogen sulphide may have been released on a large scale from the extensive marshes and harbours of the Solent estuaries in the Chichester area. This is probably the cause of the smell of pitch and sulphur and the cloud. It is well-known that earthquakes can release methane from deep oceans (see for example: Earthquakes Contribute to Global Warming by Releasing Methane from Ocean Floor. Science World Report, July 29th 2013.). There seems to be no reason why this should not happen from the extensive muds of the salt marshes and shallow sediments of the large estuarine system, adjacent to the main surface location affected by a major earthquake.
It is also possible, as an alternative explanation, that there should be gas and oil escape from the major oilfields of the southwestern Weald of Sussex. These are near Chicester. For example, Singleton oilfield is about 11km to the north, and Markwell's Wood oilfield is only 13km to the northwest of Chichester Cathedral. There are other oilfields in the region. However, the major faults of the oilfields are Late Cimmerian and therefore do not normally continue to the surface. They end beneath the Gault unconformity and do not normally continue up through the Chalk. It is not impossible that some faults have not been reactivated in Tertiary times and they might provide a pathway. The estuarine marsh methane explanation seems a simpler and more likely explanation, though.
[Separate matter: Note that the north-west tower of Chichester Cathedral collapsed in 1635 (Wikipedia), before this earthquake; I do not know whether any small error of date is possible here.]

[1666. January 18th. Oxford, Belchington, Stanton, Coventry, Brill, etc. At the same time in Hungary. ]

[1671. On the coasts of the English Channel and the German Ocean [i.e. North Sea]. At St. Malo, Havre, Calais, Dunkirk and as far as Antwerp. (Mallet, 1858, p. 89). ]

[1683. September 28th. Oxford and the neighbourhood. Also felt at Burford, Watlington, Brill and other places in Berkshire. The noise extended to Dourton in Buckinghamshire but the shock there was unappreciable. "A man who was fishing in the Cherwell at Oxford perceived the boat to tremble under him and the little fish showed signs of alarm. ... The ignis fatuus ["Will of the Wisp" - ignited methane] - had been often seen some days before the earthquake. (Mallet, 1858, p. 95, with a little more information.].

1692. unconfirmed. Portsmouth. "Portsmouth inhabitants have felt earthquake tremors on at least four occasions in 1692, 1734, 1750 and 1834." ( The Tale of One City - Portsmouth, Online. ).

[1692. September 18th. A major cross-channel earthquake. France, Paris, Normandy, England, Flanders, Holland. Brussels, Antwerp and Ipswich, Deal, Dover, Sheerness . Very violent, lasted two minutes. Several references. See Mallet, 1858]

[1696. Falmouth. Mallet, 1858.]

1707, Chichester, and Coast from Havant to Shoreham. Moderate earthquake 25th October, 3.30pm. (Davison intensity 5), cat. No. 79. (Milne, vol. 31, p.96), (Davison, 1924).

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1734, Portsmouth, Milton, and other places. Strong earthquake, (coastal, long east-west distance), 25th October, about 1 am. Cat. No. 87. (Gentleman's. Magazine vol. 4, 1734, pp. 571, 625; Milne vol. 31, p. 96.). David Kerridge, from the British Geological Survey, said there was... a magnitude 4.5 quake in 1734.

1734, Portsmouth and Sussex. - moderate earthquake 25th October (same day as the last one), about 3.50am. (Davison intensity 5). (About 4.5 ML.) Also felt in France. (Sussex earthquake in 1734, reported by Thomas Short (1749), see Musson, 2004; mentioned as Portsmouth in Wikipedia). Also reported in Philosophical Transactions., vol. 39, 1738, pp. 361-366; London Magazine, 1734, pp. 551 and 606.
"A strong earthquake, felt especially at Portsmouth, Chichester and Lewes, and at intermediate places along and near to the coast, but apparently at no great distance inland. At Lewes two shocks were felt. At Havant there was a quick tremulous motion lasting 2 or 3 seconds, repeated after a short interval."
Mallet: "In Sussex, especially Havant, Arundel, Goring, Tarning, Shoreham. Also felt at Goodwood, Portchester and Chichester. In France at Havre and as far as the other side of the Seine." The latter comments suggest that the notable Bembridge - St. Valery en Caux line was involved

[1738, January 9th. Scarborough in Yorkshire and Taunton in Somerset (?). Mallet (1858).]

1750, Newport, Isle of Wight and Portsmouth Earthquake, 18th March. About 4.3 ML. (Wikipedia List)(Also: BGS. UK Historical Earthquake Database). The epicentre was in the English Channel directly south of Ventnor. The greatest magnitude, 5, was felt at Newport, Isle of Wight. It was felt at Havant. (The British Geological Survey has referred to an earthquake of magnitude 4.3 in 1750, presumably this one.)

1750, Portsmouth Major Earthquake, 29th March, about 5.45pm. (or 6pm). (Davison Intensity 7, not modern magnitude), affected Bridport, Dorset to Brighton, Sussex. "This was one of the most important of a remarkable series of earthquakes. The boundary of the disturbed area is approximately a semicircle of about 150 miles in diameter with its centre near Portsmouth. It was felt as far Bridport, Bath, Hertford, Loughton, Bromley, etc and was strongest in the neighbourhood of Portsmouth and the Isle of Wight. The disturbed area probably contained about 18,000 square miles. At Portsmouth a jarring was felt, succeeded immediately by three or four slow vibrations, the whole movement being accompanied by a noise like distant thunder." (Davison, 1924, pp. 325-326).

1750, Isle of Wight, March 30th, 3.30am, Newport, St. Helens etc., a shock felt. (Davison, 1924).

1750, Isle of Wight, April 6th, 3 or 4am. Cat. No. 107 (Milne, vol. 31, p. 99). A shock felt in the Isle of Wight.

1750, Wimborne, Dorset and the country for 20 miles around. One violent shock. (Unusual location.)

1750, Isle of Wight, September 18th, 6 pm. Cat. No. 111 (Milne, vol. 31, p. 99). A shock felt at Portsmouth and the Isle of Wight.

1752. Feb. 23rd. Dartmoor in Devonshire. Mrs Bray's Borders of the Tamar and Tavy. Mallet.

1752. 31st March. Bristol and other places in Somerset . A considerable shaking from S to N. Mallet.

1752. April 16th. In Somerset. Mallet.

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1755. November 1st. THE LISBON EARTHQUAKE.

"The Great Earthquake of Lisbon." (Mallet). "This earthquake, one of the most violent and widely extended n record produced sensible effects over a space of the earth's surface included between Iceland in the north, Mogador in Morocco on the south, Toplitz in Bohemia on the east, and the West India islands on the west. Actual shocks were not felt over the whole of the surface; in some places agitation of the water in lakes, canals etc. being the only sensible effect produced. ... Lisbon was utterly ruined with the loss of 12,000 houses. (Mallet, p. 163).

"It lasted perhaps ten minutes, has retrospectively been measured at nine on the Richter scale, and unleashed the same day a tidal wave that wiped out much of the harbour area of town, and set off tremors that were felt in Hamburg, in Cork and even on Loch Lomond, where the water suddenly lurched upwards. Its effects covered an area of six million square miles - twice the size of Australia." Extract from the Spectator, 8th Nov. 2008 review of book on the Earthquake - Edward Paice Quercus. Wrath of God, The Great Lisbon Earthquake of 1755.]

There were tsunamis in southwestern England Channel and Bristol Channel. There were minor effects elsewhere in England , mostly seiches or movement of water. (Mallet, see p.168).

1755: LISBON EARTHQUAKE, EFFECTS ON THE SOUTH OF ENGLAND.
9.40am. Lisbon, Portugal (local time). Magnitude (modern system) 8.5 - 9. (20 time stronger than the 1906, San Francisco Earthquake). 60,000 people killed. There were major tsunamis, 5 to 10 metres high. These wrecked ports in Portugal, Spain and Morocco.

Smaller tsunamis, up to about 3m height and generally not damaging, were recorded in the southwest Britain area, particularly several hours after the earthquake.

LISBON - MORNING TSUNAMI IN THE ENGLISH CHANNEL (ABOUT ONE METRE?);
(within an hour of the Lisbon Earthquake)

Dartmouth, Devon, about 9 am. Sea level rose above the level of the highest tides and retained this height for three-quarters of an hour.

Portsmouth at 10.35 a.m.. "At Portsmouth the agitation of the sea was so great that 70 and 86 gun-ships rolled to the extent of 3 feet." (Mallet, p. 169) i.e. there was a tsunami in the morning of at least 3 feet (about a metre) and perhaps more.

LISBON - AFTERNOON TSUNAMI IN THE ENGLISH CHANNEL (2 TO 3 METRES, REPEATED WAVES)
(about 4 hours after the Lisbon Earthquake)

Tsunami waves came in to the western English Channel in the afternoon, about 4 hours after the Lisbon Earthquake. They repeatedly washed in and out, continuing for several hours. The effect was worst in the southwest. Wikipedia states that a 3 metre tsunami hit the coast of Cornwall (although data for Mounts Bay suggests 2.4 metres there). Specific data is given by Mallet (1858).

Mounts Bay, Cornwall, began at about 2 pm. Tsunami height was about 6 ft or 1.8 metres. It lasted 5 hours. It was very violent. Wave height was 8 ft or 2.4 metres at 4 pm.

Penzance, Cornwall, began at 2.45 pm. Flux and reflux lasted 3 hours.

Plymouth, Devon, at time of high water, at 4pm, the sea retired and came back in 8 minutes, the height in each case being 6 ft or 1.8 metres. This "continued for some time"

(There were also records of tsunami effects at St. Ives and Hayle on the northwest coast of Cornwall, not far from Penzance, and also at Swansea, in Wales, at 6.45 pm. Thus the afternoon tsunami travelled up the Bristol Channel.)

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1756, Extensive shocks in the Alps; also felt at London, Dover, Deal, Margate, Canterbury (Mallet).

1757, Scilly Isle and Cornwall. 6.15 pm. "Most violent in the island of St. Marys, and extending with diminished intensity to Penzance, Marazion, St. Ives (6 English miles from Penzance), Tohidy, Redruth, St. Coulomb, Bodmin to Camelford, 90 English miles from the Scilly Isle. At Lostwithiels, Liskeard, and even at Loo and Plymouth they were slightly felt."
"In some of the Cornish mines these shocks were very strongly felt. Rolling noises, like thunder or waggons in motion, were heard in the mines, at depths varying from 18 to 70 fathoms. Moveable bodies were visible shaken but no damage was done."
At Penzance beach it is interesting that water-escape structures were actually seen during their formation. They seem to have been like the ancient ones so well-known from the Permo-Trias of the Exmouth area, and usually attributed to penecontemporaneous earthquake activity. It is surprising that the structure were seen before the earthquake, but perhaps they resulted from some minor precursor. Here is the account from Mallet:
"On the morning of the 15th [of July, 1757] a fresh northwesterly wind blew, and the air was cold. On the strand at Penzance unusual marks were observed in the sand at 10am [this was before the earthquake and was presumably seen on the low tide sand flats]. Where it was generally quite smooth a space of about 100 square yards was covered with little elevations like mole-hills with holes in the tops "as if something had issued thence" and separated by little depressions of equal distance. From one of these depressions a jet of water of the size of a man's wrist issued, a phenomenon never observed before or after."

1758, 2am, 21st January. In the parishes of Worth and East Grinstead, Sussex, Lingfield in Surrey, and Edenbridge in Kent. Very minor. "A slight trembling lasting but a moment." (Mallet, 1858).

1758, About midnight, 20th December. London and the neighbourhood. A slight shock. (Mallet, 1858)

1758, 10pm. Liskeard in Cornwall [with Earthquake Light]. One shock "of a vibratory character, lasting two or three seconds. Blood red rays were observed, converging on one dark spot in the heavens. This phaenomena lasted fifteen minutes. (Probably an aurora)" [quoted from Mallet, 1858, p. 134; original source - Doddesley's Annual Register, vol. 11, p. 88.] [These blood red rays were presumably an "Earthquake Light" a rare feature for England, and perhaps due to particular conditions of electrical charges. See internet web pages on the topic of Earthquake Lights.]
[Note there was another earthquake at Liskeard and surrounding area on the 1st June 2001. See: Earthquake Rocks Devon and Cornwall. Mail Online News. Extract: "Dozens of householders were woken during the night after an earthquake measuring 3.6 on the Richter scale rocked parts of Devon and Cornwall, .. .. The quake occurred just before midnight and its epicentre was in the Bristol Channel 25 miles (40kms) west of Bude on the Cornish coast, a spokesman for the British Geological Survey said. The earthquake measured 3.6 on the Richter scale and there were reports of houses vibrating and rumbling... Police said there were no reports of any injuries but there were some cases of structural damage to buildings."]

1761, 6th February, Sturminster. Attended with a rumbling noise. [Is this Sturminster Newton, Dorset?]. Ref. Annual Register, vol 4, p. 69, quoted by Mallet (1858) p. 139.

1761, 31st March, Lisbon [again, see Lisbon 1755], 12.05 pm. A very violent earthquake. Sea rose 8 feet at Lisbon. There was a 6 foot tsunami at Mount's Bay in Cornwall at 5 pm, and the sea rose to this height five times in the space of an hour. There was a 2 foot tsunami at Kinsale, Ireland. There was significant flux and reflux of a tsunami at Cape Finisterre at fifteen minutes past twelve. This seems to have been a smaller version of the 1755 earthquake, with much less land and sea effects. There was wave agitation, i.e. a distant tsunami, in Barbadoes eight and a half hours after the shock at Lisbon. This is the second time an earthquake at Lisbon has caused a tsunami to reach the British Isles, although the effects were less on this occasion. (Details from Mallet, 1858, p. 140).

1761. 9th June. 11.55am. Sherborne, Shaftesbury and the country around for 13 miles. Just a record of an earthquake. No details.

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1811, Chichester Region. November 30th, about 2.40am. Cat. No. 256; Davison intensity 5. Centre of disturbed area in lat. 50 50 N., long. 0 50 W. Records from 11 places in Chichester region. Fig. 83 in Milne, vol. 31, p. 115; Edin. Adver. The disturbed area is 30 miles long, 20 miles wide and contains about 470 square miles. Its centre is 2 miles WSW of Chichester (Davison, 1924). This is important in fixing Chichester as an epicentre; some other earthquakes which have affected Chichester may have been really located in the English Channel to the south. This almost tends to match on a smaller scale the big Portsmouth Earthquake of 29th March 1750. (Both may relate to deep faults in the Chichester - Winchester area.)

1814. Portsmouth, December 6th, a few minutes before 2 am. Cat.no. 304. (Ann. Reg. 1821, p. 20). See Davison, p. 327. "A shock felt very generally in and near Portsmouth as far [east] as Arundel.

1821. February 1st. Alfriston, Sussex. (about 60km east of Chichester and near Eastbourne) About 2.30 -. Cat. No. 304. (Ann. Reg. 1821, p. 20.) Alfriston, Cuckmere Valley, East Sussex. "A tremulous motion, accompanied by a noise like the rumbling of heavy carriages over stones, at Alfriston. (Davison, 1924, p. 327).]

1824. Chichester, December 6th, centred around the town, (Davison Intensity 5). Centred around the town, but affected an area 25 miles long from SW to NE and 17 miles wide. Area affected 330 square miles (much smaller than the 1750 earthquake. Records from 8 places. Phil. Mag, vol. 65, pp. 70-71, 1825; Ann. de Chim. et de Phys, vol. 27, 1824, p. 380. Centre of disturbed area - lat. 50, 50 N., long. 0, 50 W. [details from Davison (1924).]

1833, 18th Sept. Chichester. Minor Earthquake. (Cat No. 330) About 10am. 2.9 ML. (UK Historical Earthquake Database. BGS. [- although check that this is the correct 1833 shock, since there was another, see below] "The shock was felt from Liphook (16 miles north of Chichester) to Birdham (3 miles SW) and possibly at Longleat (near Poole, about 52 miles from Chichester). It resembled the thud caused by the fall of a heavy body, followed by a vibration. It was felt by a boat's crew in Chichester harbour, the impression conveyed being as if the boat had suddenly struck on a rock. In Stanshead Forest and elsewhere, pheasants crowed as they usually do when the evening gun at Portsmouth is fired." (after Davison (1924))

1833, 13th November, 2.40am. Chichester area. (Cat. No. 331). "The area disturbed was nearly the same as in the preceding earthquake but extended a little further to the north. The shock consisted of a series of rapid undulations and was preceded by a low sound."

1833, 13th November, 6 am. Chichester. A much slighter shock than the preceding, felt in Chichester and the immediate vicinity.

1834, 23rd January, 2.45 am. Chichester and Portsmouth. 3.2 ML. according to the UK Historical Earthquake Database. BGS. Recorded by Davison (1924) as intensity 5. Centre of disturbed area - lat. 50, 52 N., long 0, 52. The boundary of the disturbed area, centred 4 miles nort-northwest of Chichester, is shown on a map of Davison. It extended to Liphook, just missed Bishops Waltham and included the northeastern part (Sandown, Bembridge etc) of the Isle of Wight. It did not affect the western Isle of Wight (further from the fault system off the eastern Isle of Wight). The shock is said to have been felt at Longleat. The shock consisted of several undulations, preceded and accompanied by a sound of the continuous falling of heavy pieces of furniture. Also reported to have been recorded at Havant and Portsmouth.
See also: 1692. "Portsmouth inhabitants have felt earthquake tremors on at least four occasions in 1692, 1734, 1750 and 1834." ( The Tale of One City - Portsmouth, Online. ).

1834, 20th February, 2am. Chichester. Cat. No. 334. A slight shock.

1834, 27th August. Chichester. 3.3 ML. (UK Historical Earthquake Database. BGS.). Records from 8 places.
"Although this shock was apparently slighter than that of January 23rd [1834], it was felt further to the west, by about 1 mile at Bishop Waltham and 7 miles at Southampton. At Chichester some loose chimney-tops were partially thrown down. The shock was a tremulous motion and was preceded by a low rumbling sound."
[During one of the earthquakes of 1833 - 1834 at Chichester, a falling rock at Cocking Quarry killed Mr William Marshall. (Wikipedia List and also the West Sussex Info Website - http://www.westsussex.info/cocking.shtml)]

1834 - CHICHESTER AREA - HORNDEAN.
Memoirs of Sir William Knighton, Keeper of the Privy Purse. Sir William Knighton,
Horndean, [near Chichester, site of the later Horndean Oilfield]
28th August 1834
"I have had a violent attack of illness: but by keeping in my bed the whole of Wednesday, I am now, thank God, tolerable. On Wednesday night we were visited by a severe shock of an earthquake. Everyone in the house was alarmed and frightened, and all left their rooms more or less terrified. Independently of the houses and furniture shaking. It was accompanied with such a noise, that it was supposed something must have happened in the large drawing room. It was, I believe, still more forbidable at Emsworth, and was felt all round the neighbourhood. "Yours etc. "W.K." [Note added in the book: The shock of the earthquake here alluded to was the most severe of several which about that time were experienced on the line of coast from Portsmouth to Chichester. It thus described in the public prints of the time. "On the morning of January 23rd, 1834, at twenty minutes before three o'clock [a.m.], the inhabitants of the city were suddenly aroused from their sleep by an extraordinary noise. At once their beds began to shake under them, the furniture in their rooms to move, and the bells in their houses to ring. All were alarmed and dismayed, numbers left their habitations and collected in the streets, where they understood the cause of their alarm. The terror, however, caused by this sudden earthquake remained upon their minds for a considerable time afterwards."]
[It is of interest that the oilfields in this area are generally limited by a Late-Cimmerian boundary fault, normal (hading northward) and originally extensional, not exactly straight, and which does not penetrate the Chalk. It has been under compression since about Bartonian times. It is unlikely to have moved but should be considered in discussion. See other reports of earthquakes in the area. A fault of much greater significance is the Bembridge - St. Valery Fault which extends to Chichester. It is not known whether there could be interactive movement, renewed by small, on the boundary fault; it is just a question.]

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1834, September 3rd, in Christiana, Norway, but felt in Chichester and Portsmouth. "At Chichester a low rumbling noise was heard before the shock. The appearance of the sunset was extraordinary and a West Indian gentleman predicted an earthquake. A whirlwind occurred to the west three hours previously. A man on the shore south of Chichester heard a loud report like that of a great gun, and immediately afterwards felt the ground shaking under his feet. [Details re Christiana follow].
"A smart shock of an earthquake was felt at Portsmouth on Wednesday night last week, about ten o'clock. Several houses were much shaken, and some slight damage was sustained. In other houses, articles placed against the walls, or upon shelves, were shaken violently." Spectator article.

1834. 31st? September Portsmouth. (6 September 1834 report - Portsmouth. reference to previous week). On Wednesday night last week, about ten o'clock. Several houses were much shaken, and some slight damage was sustained. In other houses, articles placed against the walls, or upon shelves, were shaken violently. ( 6 September 1834, page 4, Spectator Archive.)

1834, September 21st. Chichester, 11.20 am. (Cat. No. 337). A slight shock at Chichester. Listed by Mallet.

1834, October 5th. Chichester. Reported as a slight shock at Chichester by Perrey (p. 155) and noted by Davison (1924). However, listed by Mallet as: "A severe shock the earth quivered for at least two minutes."

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1835. August 3rd. Chichester. "A shock and rumbling sound in the neighbourhood of Emsworth Common (7 miles west of Chichester), with a violent rustling of trees. The whole account is suggestive of distant gun-firing (Nature, vol. 39, 1889, p. 231). (Recorded by Davison, 1924).

[1861, the spire of Chichester Cathedral fell; there is no known connection with earthquakes. Spire rebuilt as an exact copy.]

1878. January 28th. English Channel, centred near Jersey. (intensity 5 on one scheme, given as 6 on another). This shock was felt along the south coast of England from Bovey to St. Leonard's, and inland as far as London and Paris. The British Geological Survey later referred to an earthquake of magnitude 5 in this (Chichester-Isle of Wight) area

1882 - Tsunami at Hurst Spit? West Solent - "Tidal Wave"
"In September, 1882, a tidal wave [tsunami] broke on the beach at Sturt filling up a considerable portion of Sturt Pond and the outlet, the salt water came up the Dane Stream, killing the fish, roach, carp, etc., and destroyed many of the apple trees in the gardens abutting on the stream. A new cutting was made near the original, but this soon filled up and the present one [in 1926] was made."
I particularly thank Jeremy Greenwood (New Forest History) for the information, which he found in the following, rather obscure, publication: Cole, A. 1926. Postmaster of Milford on Sea. Some Further Recollections of Milford, no. 23. Milford-on-Sea Record Society: Occasional Magazine, Volume 3, no 4, 1926.
(There was a magnitude 7.9 earthquake at Panama in 1882, which also created a tsunami. It is not known whether there was any possible connection with this. It seems too far away!)

1889. May 30th. A Channel Island earthquake, strongest in Guernsey and near Cherbourg. Felt in London and Paris. Noted at Bognor, Bournemouth, Surbiton and Wareham. Thus it would be expected that it might have been felt at Chichester.

[1896, December 17, Thursday, 5.32am (BGS). Wales, London, Midlands and Bristol. Report in December 1896 - Spectator Archive. Hereford, the pinnacles of the Church fell down and the Cathedral was badly shaken. On last Thursday morning at 5.30am. Chichester or Portsmouth not mentioned in the article.]

1963, 25th October, Chichester 4.7 ML (UK Historical Earthquake Database). It physically rocked Portsmouth and the epicentre was said to be off Chichester. This earthquake. was recorded by instruments at Kew Observatory. (some notes from On the Wight webpage, 2011).

1970 (no details found)

2001, 1st June. Liskeard, Cornwall and surrounding area. See: Earthquake Rocks Devon and Cornwall. Mail Online News. Extract: "Dozens of householders were woken during the night after an earthquake measuring 3.6 on the Richter scale rocked parts of Devon and Cornwall, .. .. The quake occurred just before midnight and its epicentre was in the Bristol Channel 25 miles (40kms) west of Bude on the Cornish coast, a spokesman for the British Geological Survey said. The earthquake measured 3.6 on the Richter scale and there were reports of houses vibrating and rumbling... Police said there were no reports of any injuries but there were some cases of structural damage to buildings."

2005, 16th July, Horsham, West Sussex. 2.9 ML (Earthquaketrack.com); (Horsham is between Balcombe and Wisborough Green, - see petroleum geology of the Weald webpage; it is about 50km NE of Chichester).

2011, 14th July, English Channel, but affected Portsmouth. 3.9 ML. (Wikipedia List and Earthquake Track) Depth 10km. Epicentre in English Channel, 72 km south of Ryde.
The British Geological Survey said the quake had a depth of 10km and its epicentre was south of Portsmouth, Hampshire. Official measurements showed it happened at 7.59am BST. David Kerridge, from the British Geological Survey, said the earthquake was the largest in the area since a magnitude 4.5 quake in 1734. "Historically, there have been two other significant events nearby, a magnitude 5.0 earthquake in 1878 and a magnitude 4.3 earthquake in 1750," he said. Guardian, Thursday, 14th July, 2011.
"An earthquake with a magnitude of 3.9 struck in the middle of the English Channel today, the British Geological Survey (BGS) said. Residents in parts of West Sussex reported buildings shaking for a few seconds but no injuries or damage has been reported. The quake struck at 7.59am, had a depth of 10km and its epicentre was around 75km south-east of Bognor, according to the BGS. It was the largest earthquake in the area for almost 300 years. One worker said it felt like a big lorry had gone by in a hurry." The Argus, University of Brighton.

2012, 14th December. Chichester. - CHILGROVE. About 3 ML. "There have been further reports of an earthquake in Chichester on Friday. The quake was felt as far away as Hindhead and Hove. However, it was only three on the Richter scale and the epicentre was thought to be near Chilgrove [note CHILGROVE - oilfield area]. This is halfway between the Singleton and Markwells Wood Oilfields, and NNE of Chichester. The Natural Environment Research Council said the earthquake began at 11.03pm on Friday." Portsmouth News, Wed. 19th Dec. 2012. This earthquake also affected in general: Chichester district, East Hampshire, Havant district, Arun district and the city of Portsmouth. [There is no particular reason to connect it to the oilfields but horizontal drilling has taken place from Singleton oilfield, and this is not far away to the east. It is more likely to be coincidence.]

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2015, 27th January, 6.30 pm. Winchester.2.9 ML - i.e. small. Also near an oilfield. (unusual location, not known for previous earthquakes, but it might be associated with the more common Chichester activity). Data from British Geological Survey. Depth: 3 km. It was said not to be the result of fracking. The oilfield, only a few kilometres to the north, is licenced to iGas or Island Gas. The epicentre was relatively shallow, but probably just into basement and rather too deep to be associated with the oilfield exploration.

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LOCALITIES:

DOVER, CANTERBURY REGION
KENT EARTHQUAKE, 22nd MAY 2015

[data from newspapers, TV, BBC website etc. Technical information source is the British Geological Survey, BGS.]

Date: Saturday, morning, 22nd May 2015.

Time: 02.52 am BST.

Magnitude 4.3

Epicentre: 7.5 miles of the Dover Coast in the English Channel

Depth: 15km (according to BGS)

Injuries: no serious injuries; one person with minor head injury.

Buildings damaged - 474, with 73 too dangerous for people to return.

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ENGLISH CHANNEL - BEMBRIDGE - ST. VALERIE LINE, 30th MAY 2017.

St. Valerie-en-Caux (i.e. the Bembridge or Chichester - St. Valerie Line )
On May 30th, 2015 a single 3.0M earthquake struck the English Channel and along the shores of France in this area, which has been the location of many earthquakes. There was a warning by Michael Janich a day in advance, that was accurate to within 1 magnitude.
(see website:
Earthquake strikes south England along the English Channel. )

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LOCALITIES:

DORSET AREA, INCLUDING POOLE AND BRIDPORT

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LOCALITIES:

SOMERSET - INCLUDING WELLS AND GLASTONBURY
1199. In England, principally in Somersetshire. Persons were thrown from their feet in some places. Mallet, 1858.

1248. In England, Somerset, in the diocese of Bath and Wells. Also felt in Piedmont and Savoy and Syria. The Cathedral of Wells was much injured. It was remarked that the summits of the building were violently shaken whilst their foundations were not. Mallet, 1858, with references, on p. 32.

1718 (or 1748, some doubt about the year), July 12. Somerset. Between 10 and 11 am. Taunton in Somerset and the country from the English Channel to the Severn and extending the same distance East and West, being felt at the same time at Exeter and Crookham. The shock appeared to come from a distance and was accompanied by a noise like a wagon in motion. Those who were sitting felt their seats move under them, and those who were in bed were wakened by a sudden start. China and kitchen utensils were thrown about and here bells were heard to ring. V. Hoff mentions two earthquakes at this place, vi. on the 1st July 1747 and 1st or 11th June 1748. Both dates appear to be erroneous. See Phil. Trans. vol. xiv, p. 398, vol. xlivi, p. 680. Listed by Mallet (1858)]

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LOCALITIES:

LONDON

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REFERENCES

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BBC News Channel. Online, 22nd May 2015. Hundreds of Quake Homes Damaged.
See: http://news.bbc.co.uk/1/hi/england/6605095.stm
[Brief Extract]
Hundreds of houses in Folkestone have been damaged by the earthquake which struck parts of Kent. Council officials say 73 buildings are so dangerous residents cannot return to them because of loose chimney stacks, tiles and masonry. They have received 474 calls from people worried about the impact of the 4.3 magnitude tremor on their homes. The Association of British Insurers said the insurance cost for the damage could reach "single figure millions". The quake which struck on Saturday morning was the largest to hit Britain since one in the West Midlands in 2002. It struck at 0819 BST but resulted in only one person, a 30-year-old woman, suffering minor head injuries. Most residents forced from their homes sought refuge with families and friends, but a small number had to be housed in emergency accommodation.
Experts from the British Geological Survey said the epicentre of the quake was 7.5 miles off the Dover coast in the English Channel. It brought down power lines with several thousand homes affected, but EDF Energy Networks said service were quickly restored in the Folkestone and Dover areas. Kent Fire and Rescue Service took more than 400 emergency calls about concerns ranging from structural damage to gas smells.

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British Geological Survey. BGS. 2015. Earthquakes - British Geological Survey Website. This is a major source of information on British earthquakes.

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British Geological Survey. BGS. 2015.
UK Earthquake Historical Database.
Select an earthquake by clicking on the date. (A very useful listing, with a map and a system of finding earthquake information by date.)

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British Geological Survey. BGS. 2015
What is Earthquake Magnitude?.
It is a measure of earthquake size and is determined from the logarithm of the maximum displacement or amplitude of the earthquake signal as seen on the seismogram, with a correction for the distance between the focus and the seismometer. This is necessary as the closer the seismometer is to the earthquake, the larger the amplitude on the seismogram, irrespective of the size or magnitude of the event. Since the measurement can be made from P, S or surface waves, several different scales exist, all of which are logarithmic because of the large range of earthquake energies... [continues]

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Daily Mail, 2011. The Worthing Wobble: Teacups rattle on the south coast after earthquake strikes in the English Channel. [3.9M quake, depth 10km, location - 85km south of Portsmouth, in the mid- English Channel.]
The quake's epicentre was around 53 miles (85km) south-east of Portsmouth, Hampshire, at a depth of 10km,the BGS said.
This is the largest earthquake within 25 km (16 miles) since a magnitude 4.5 event in 1734,' David Kerridge, from the BGS, added. Historically, there have been two other significant events nearby (30km to 40km distant) - a magnitude 5.0 earthquake in 1878 and a magnitude 4.3 earthquake in 1750.

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Davison, C. 1924 [reprinted 2009]. A History of British Earthquakes. By Charles Davison Sc.D, F.G.S. Cambridge University Press. 416pp. This classic volume details the history of British earthquakes from the year 974 to the beginning of the twentieth century. Building on material laid out in his 1912 volume The Origin of British Earthquakes, Charles Davison based his method of investigation on the theory that earthquakes were the results of successive steps in the growth of faults. Using a modification of the well-known Rossi-Forel scale, and with reference to the latest scientific studies of his time, he compiled a catalogue of all known British earthquakes. ....
See particularly:
Chapter 16: Earthquakes of the South of England (Dorsetshire Earthquakes, Wiltshire Earthquakes, Hampshire Earthquakes).
Chapter 17: Earthquakes of the South-East of England (Chichester Earthquakes, Lewes Earthquakes, Canterbury Earthquakes, Reigate Earthquakes, Maidstone Earthquakes, London Earthquakes, St. Albans Earthquake, Colchester Earthquakes.
Extract from Introduction, p.3.
"In the autumn of 1833, a centre near Chichester, which had been in action from time to time for nearly two centuries, gave rise to a series of moderately strong earthquakes that continued for nearly two years. . These earthquakes were studied by an unofficial committee in Chichester, of which Mr J.P. Gruggen was secretary. The report which he drew up was communicated to the Royal Society, but only a very brief summary was published. Of considerable value in itself, it is interesting as the first report of a committee instituted for the study of British Earthquakes. .. continues" [The origin Chichester Earthquake report is not published but is preserved in the Archives of the Royal Society, and extracts are used in this book by Davison.]

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Earthquake Track - Website.
Earthquake Track.
3.7 magnitude earthquake 47 km from Dinard, Bretagne, France. 2km depth [i.e very shallow]. Wednesday, 22:55pm (UTC time), 25th Februay, 2015.
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Fabyan, R. 15??. Fabyan's Chronicle. By Robert Fabyan, draper, Sherif and Alderman, and early London Chronicler. He died about 1512. Not seen. His work is referred to by Davison as the source of records of various historic British earthquakes.

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Geology Shop. 2015. UK Earthquakes. . Introduction: While the UK is nowhere near in the same league as high seismicity areas such as California, Taiwan and Japan, it nevertheless has a moderate rate of seismicity, sufficiently high to pose a potential hazard to sensitive installations such as, nuclear power stations, dams and chemical plants. Consideration also has had to be made for other large construction projects such as the Channel Tunnel.... [continues.]

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Luard, H.R. (editor). 1868-9. Annals of Osney and Worcester. Annales Monastici, Vol. IV. Longman, Green, Longman, Roberts and Green, London.

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Mallet, R. 1852. Catalogue of Recorded Earthquakes from 1606 B.C. to A.D. 1850. British Association for the Advancement of Science, Report, 1852, pp. 1-176; 1853, pp. 118-212; 1854, pp. 2- 326. By Robert Mallet, Irish Geophysicist, "father of seismology". By Robert Mallet and John William Mallet. "On the Facts of Earthquake Phenomena." 28th Report of the British Association for the Advancement of Science. A copy of the book is available, free, online.

Mallet, R. and Mallet, J.W. 1858. The Earthquake Catalogue of the British Association with Discussion, Curves, and Maps, etc. By Robert Mallet, C.E., F.R.S. and John William Mallet, Ph.D., Professor of Chemistry, University of Alabama. From the Transactions of the British Association for the Advancement of Science, 1852-1858. London. Printed by Taylor and Francis, Red Lion Court, Fleet Street. [This is available from Amazon as a thick volume in photocopy style (marked Stanford Library, 300834, 55i22, M253). It has hundreds of pages, mostly tables and some maps and diagrams at the back. The text is clear in this version, but the diagrams are imperfect. There is also available a computer text recognition version, but this has not been seen. Experience with other publications using text-recognition methods has not been good, and the photocopy-style version has been chosen by the present writer.]

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Milne, D. 1841. Notices of Earthquake-Shocks felt in Great Britain, and especially in Scotland, etc. By David Milne (afterwards - Milne Home). Edinburgh New Philosophical Journal, vol. 31, 1841. Reprinted with additions in 1887. There are a series of page and volume numbers which are given in Davison (1924) p. xvii.

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[See many other publications by Musson, not given here. See reference list in Musson (2007).]

Musson, R.M.W. 1994. A Catalogue of British Earthquakes. British Geological Survey Global Seismology Report, WL/94/04.

Musson, R.M.W. 2007. British Earthquakes. Proceedings of the Geologists' Association, vol. 118, pp. 305-337. By R.W.M. Musson of the British Geological Survey.
Abstract: Although the UK is not a strongly seismic region, the study of earthquakes in Britain presents many interesting points. First, British earthquakes are rather well documented throughout history, partly due to the intellectual development and literacy of the country and partly because British earthquakes have always been so newsworthy that even minor events have been recorded in some detail. Secondly, as is rather typical for intraplate areas, the relationship between seismicity and geological structure is unclear. The definitely non-random spatial pattern of British earthquakes is clearly due to something. However, among competing theories as to what that something is, no hypothesis is clearly the best. In this paper, the subject of British seismicity is viewed from several angles. First, the sources that underlie the earthquake catalogue are discussed in order to give a clear indication of the limits on the completeness and accuracy of the data. General statistics for earthquake occurrence in the UK are then presented. This is followed by a description of British seismicity from region to region, with remarks on some key earthquakes of interest. Different hypotheses on the nature of the tectonic or geological control are then reviewed and assessed. Finally, the subject of active faults in the UK is discussed, from the point of view of general seismic hazard assessment.

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Neilson G., Musson R.M.W. and Burton P.W., 1984. Macroseismic reports on historical British earthquakes VI: The South and Southwest of England. BGS, Global Seismology Report No 231. Macroseismic Data Points available at http://quakes.bgs.ac.uk/historical/.

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Wikipedia: 1580, Dover Straits Earthquake, Go to:
Dover Straits Earthquake, 6th April 1850. [a deep earthquake]
"The Dover Straits earthquake of 6 April 1580 appears to have been one of the largest in the recorded history of England, Flanders or northern France. ..... A study undertaken during the design of the Channel Tunnel estimated the magnitude of the 1580 quake at 5.3 - 5.9 ML and its focal depth at 20-30 km, in the lower crust. The British Geological Survey estimates the magnitude to be 5.7 - 5.8 ML."
"On the English coast, sections of wall fell in Dover and a landslip opened a raw new piece of the White Cliffs. At Sandwich a loud noise emanated from the Channel, as church arches cracked and the gable end of a transept fell at St Peter's Church. Near Hythe, Kent, Saltwood Castle ... was rendered uninhabitable... "
Other earthquakes in the Dover Straits.
Two later quakes in the Dover Strait, in 1776 and 1950, both thought to be around magnitude 4, were noted .. Some scientists have suggested that the 1580, 1776 and 1950 quakes are all linked to periodic tectonic activity that results in a tremor occurring in the Dover Straits approximately every 200 years.
The 2007 Kent earthquake was initially thought to have occurred in the Dover Straits, but later analysis showed it to have occurred directly under the town of Folkestone in Kent.

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Wikipedia, 2015. List of Earthquakes in the British Isles. [An important and very useful listing]
"The following is a list of notable earthquakes that have been detected in the British Isles. On average, several hundred earthquakes are detected by the British Geological Survey each year, but almost all are far too faint to be felt by humans. Those that are felt generally cause very little damage. Nonetheless, earthquakes have on occasion resulted in considerable damage, most notably in 1580 and 1884; Musson (2003) reports that there have been ten documented fatalities – six caused by falling masonry and four by building collapse. The causes of earthquakes in the UK are unclear, but may include "regional compression caused by motion of the Earth’s tectonic plates, and uplift resulting from the melting of the ice sheets that covered many parts of Britain thousands of years ago." [.. continues. ]

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Young, J. 2014. Mexico, Alaska and the English Channel: Earthquakes 23-30 July 2014. (in website by Jennifer Young).
See this Online at:
Decoded Science, 2014, by Jennifer Young.
Channel Islands Earthquake [2014]
"[In July 2014] - an earthquake of M4.0 struck in the English Channel, south of the island of Jersey. It follows a tremor of M3.9 earlier in July. Though small in global terms (and felt only in the immediate area) these tremors are unusual for their location. Two tremors have struck recently in the English Channel [an another one on 22nd May 2015 nine and half miles offshore from Kent]. [Image credited to: USGS] The epicentre is far from tectonic margins and the Channel is largely stable and does not even merit a mention in most listings of active seismic areas. But it is active, nonetheless, though on a small scale. There is no detailed information on the causes of the earthquake but the geological context is of a sedimentary basin which is subsiding. The area is further influenced by the a process known as isostatic rebound. During the last Ice Age the weight of Ice on the northern parts of the British Isles forced the areas to the south upwards in a 'see-saw' effect. With the melting of the ice this process is reversing (on a timescale of thousands of years) with the result that the area is sinking...."
[the text here has been slightly modified]

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[Temporary addition:

This earthquake was in the area of the oilfields at Horndean and eastward. Most of these oilfields have a major boundary fault of Late Cimmerian, extensional type to the south. See the following report of the 1834 earthquake at the site of the Horndean Oilfield. However, note that the earthquake was also felt at Le Havre

"Memoirs of Sir William Knighton, Keeper of the Privy Purse.
Sir William Knighton,
Horndean,
28th August 1834
"I have had a violent attack of illness: but by keeping in my bed the whole of Wednesday, I am now, thank God, tolerable. On Wednesday night we were visited by a severe shock of an earthquake. Everyone in the house was alarmed and frightened, and all left their rooms more or less terrified. Independently of the houses and furniture shaking. It was accompanied with such a noise, that it was supposed something must have happened in the large drawing room. It was, I believe, still more forbidable at Emsworth, and was felt all round the neighbourhood. "Yours etc. "W.K." [Note added in the book: The shock of the earthquake here alluded to was the most severe of several which about that time were experienced on the line of coast from Portsmouth to Chichester. It thus described in the public prints of the time. "On the morning of January 23rd, 1834, at twenty minutes before three o'clock [a.m.], the inhabitants of the city were suddenly aroused from their sleep by an extraordinary noise. At once their beds began to shake under them, the furniture in their rooms to move, and the bells in their houses to ring. All were alarmed and dismayed, numbers left their habitations and collected in the streets, where they understood the cause of their alarm." The terror, however, caused by this sudden earthquake remained upon their minds for a considerable time afterwards.]

----------------- Copyright © 2017 Ian West, Catherine West, Tonya Loades and Joanna Bentley. All rights reserved. This is a purely academic website and images and text may not be copied for publication or for use on other webpages or for any commercial activity. A reasonable number of images and some text may be used for non-commercial academic purposes, including field trip handouts, lectures, student projects, dissertations, exhibitions etc, providing source is acknowledged.

Disclaimer: Geological fieldwork involves some level of risk, which can be reduced by knowledge, experience and appropriate safety precautions. Persons undertaking field work should assess the risk, as far as possible, in accordance with weather, conditions on the day and the type of persons involved. In providing field guides on the Internet no person is advised here to undertake geological field work in any way that might involve them in unreasonable risk from cliffs, ledges, rocks, sea or other causes. Not all places need be visited and the descriptions and photographs here can be used as an alternative to visiting. Individuals and leaders should take appropriate safety precautions, and in bad conditions be prepared to cancell part or all of the field trip if necessary. Permission should be sought for entry into private land and no damage should take place. Attention should be paid to weather warnings, local warnings and danger signs. No liability for death, injury, damage to, or loss of property in connection with a field trip is accepted by providing these websites of geological information. Discussion of geological and geomorphological features, coast erosion, coastal retreat, storm surges etc are given here for academic and educational purposes only. They are not intended for assessment of risk to property or to life. No liability is accepted if this website is used beyond its academic purposes in attempting to determine measures of risk to life or property.

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Dr Ian West, author of these webpages

Webpage - written and produced by:


Ian West, M.Sc. Ph.D. F.G.S.

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at his private address at Romsey, Hampshire, kindly supported by the School of Ocean and Earth Science, Southampton, Southampton University and web-hosted by courtesy of the iSolutions of Southampton University. Field activities shown in this website are not necessarily those of Southampton University, some are of private visits, or of various organisations. The procedures and the safety aspects vary according to weather conditions, cliff state and whether the field trip is an organised one, a tourist trip, or merely a private visit.


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