Thursday, 23 February 2012

Earthquakes in Jersey and Guernsey

A "Wrinkle in the Skin" by the science fiction writer John Christopher has cataclysmic earthquakes which destroy most of Guernsey and drain the English Channel. The novel follows the story of a vinery worker's attempt to reach his daughter in England, by walking! That is perhaps, somewhat far-fetched, as the area is relatively geologically stable.

Nevertheless, there have been a surprising number of earthquakes reported in the Channel Islands, possibly slightly more in Jersey than in Guernsey. The Times newspaper reports the following over the period from 1790 to 1900 - quite a large number, and also notable enough to make a national British newspaper:

Tuesday February 05 1799 Earthquakes - Shocks in the Island of Jersey
Saturday February 09 1799 Earthquakes Shocks in the Island of Jersey
Friday August 03 1832 Earthquakes at St. Helier's, Jersey
Saturday March 18 1843 Earthquake in Guernsey
Saturday December 30 1843 Earthquake in Guernsey
Tuesday January 02 1844 Earthquake in the Channel Islands
Monday January 15 1844 Earthquake in the Channel Islands
Tuesday April 05 1853 Earthquake in Jersey
Wednesday April 08 1868 Jersey, Earthquake
Wednesday August 27 1884 Earthquakes in Jersey
Friday April 22 1887 Earthquake in Jersey and Guernsey
Wednesday April 27 1887 Earthquake in Jersey and Guernsey
Friday May 31 1889 Earthquake in Guernsey

The last must have been quite notable, for the Reverend Alban E Ragg, writing in his 1896 "Popular History of Jersey" reports that May 1889 "ended on the 30th with a severe shock of earthquake."

The British Geological Survey has records of an earthquake in 1926, on 30th July 1926:

This strong earthquake was felt throughout NW France and as far E as Paris, and along the S coast of England, principally in Dorset and Devon, but as far east as Hove, Sussex. The epicentre was between Jersey and the Cotentin coast. In Jersey there was much damage of a slight nature, plaster cracking, windows breaking, etc. A church spire was damaged and some few chimneys fell. A small amount of damage was also caused in France

This was a fairly strong earthquake, which caused considerable damage to the Fisherman's Chapel - so much so that the Reverend John A. Balleine (Rector 1892-1942) had to undertake considerable remedial work, but when writing it up, he confused the quake of 1927 with that of 1926:

"The earthquake of 30th July, 1927, shook the sea wall and the foundations of the Chapel to such an extent that a great length of the former had to be rebuilt and the latter underpinned."

The British Geological Survey has records of an earthquake in 1927. This occurred on 17th February 1927 around 17 minutes past 11 at night, and had a magnitude of 5.4 ML. The report notes that:

The epicentre of this earthquake appears to be the same as that of the 30 July 1926 event some 6½ months previously - East of Jersey, near the West coast of Cotentin, France. The magnitude was slightly smaller and the maximum intensity certainly less. There was very little damage reported in Jersey, mostly confined to plaster and in many cases probably exploiting weaknesses caused by the 30 July 1926 event. The earthquake was felt at low intensities along the South coast of England from Falmouth, Cornwall, to Worthing, Sussex, and also slightly in London and Newbury, Berks. The limits of perceptibility in France seem to be Lisieux in the East and Lorient in the South West. As with the 27 December 1896 Hereford earthquake, something like a meteor was observed at the same time as the earthquake.

It seemed to be a time of earthquakes - coincidentally, across the globe, in 1927, newspapers reported on the highest intensity earthquake ever observed in New Jersey.

Probably the best detailed observations of an earthquake that I've found is from the Victorian period. "An Account of a slight Shock of an Earthquake felt in the Channel Islands." by J. Elliott Hoskins, M.D,, F.R.S. : in a Letter to P. M. Roget, M.D., Sec. R.S., &c. Communicated by Dr. Roget. This appears in the Abstracts of the Papers Communicated to the Royal Society of London (1843-1854). 1843-01-01. 5:498-499, and describes the earthquake of 1 January 1844.

Here is the complete text; I've kept the original spellings - Serk, Herne, and Jethore - which are exactly as they appear in the document:

An Account of a slight Shock of an Earthquake felt in the Channel Islands, January 1844

The phenomena described in this letter occurred simultaneously in Jersey, Guernsey, Alderney, Serk, Herne, and Jethore. On Friday, the 22nd of December, at seven minutes before 4 p.m., a noise resembling a distant thunder-clap was heard ; this was immediately followed by sounds as of a railroad carriage rumbling over an irregular metallic surface ; it was accompanied by distinct undulatory motion. This again was succeeded by a shock; the whole lasting from 10 to 15 seconds. The barometer was uninfluenced, standing at 30:354 : a light wind prevailed, varying from S.S.E. to S.S.W. During the whole of the month the air had been peculiarly still, and the barometer uniformly high ; the maximum, up to the above date, having been 30:518, the minimum 30:042.

The thermometer had ranged throughout the month, from 47° to 52° during the day, and from 45° to 49° during the night.

Hundreds of persons agree as to having experienced a distinct shock, their impressions varying according to the positions occupied by the observers. Those inhabiting the solid granite structures of the lower town conceived that heavy masses of furniture were overturned and moved in the apartments above or below them: they were not, however, so conscious of vibratory motion as those in the less substantial houses of the upper part of the town, or as those in the open air. In many houses, this vibratory motion was so violent as to cause much alarm, and was accompanied by crashing sounds, as though roofs and chimneys were falling ; in some instances, chimney-pots were thrown down ; suspended lamps were observed to wave ; bells rang spontaneously ; the vane of the town church waved, and one of its bells struck twice.

Persons in the open air were sensible of an undulatory motion, tending from the S.W., which occasioned unsteadiness of footing, and in some cases a transient feeling of nausea. A steam-engine in the Serk mines was remarked to suspend one out of its usual five strokes per minute ; the engineer was alarmed lest this should be a precursor of bursting of the boiler. The massive granite works of St. Sampson's quay were so shaken, that glass vessels situated on various parts were thrown off. Two gentlemen engaged in Daguerreotype experiments on the ramparts of a fortification founded on a solid granite rock, felt the whole to vibrate.

The crews of sailing-vessels beating up in the "roads," also felt the shock; those below rushing on deck under the impression that the vessels had struck on a rock.

The testimony of a great number of witnesses leaves no doubt as to the distinctness and strength of the shock. It was also felt, though in a slighter degree, in the neighbourhood of St. Malo, and near Brixham in Devonshire.

1 comment:

Anonymous said...

Interesting, thanks

I was puzzled what Daguerreotype experimemts could be, and looked it up :)