1984 Lleyn Peninsula earthquake
Encyclopedia
The 1984 Llŷn Peninsula earthquake struck the Llŷn Peninsula
in Gwynedd
, north-west Wales
on 19 July 1984 at 06:56 UTC
(07:56 BST
). It measured 5.4 on the Richter scale
, and is the largest known onshore earthquake
to occur in the UK
since instrumental measurements began.
The effects were felt throughout Wales, most of England
and parts of Ireland
and Scotland
. There were many reports of minor damage to chimneys and masonry throughout Wales and England, the biggest concentration of damage being in Liverpool
, which is located around 65 miles north-east of the epicentre. Minor injuries were also reported in the areas surrounding the epicentral area, and rockslides occurred at Tremadog
in Gwynedd.
It was followed by many aftershock
s in the following months, the largest measuring 4.3 on the Richter scale, which itself was felt as far away as Dublin, in Ireland.
Llŷn Peninsula
The Llŷn Peninsula extends into the Irish Sea from north west Wales, south west of the Isle of Anglesey. It is part of the modern county and historic region of Gwynedd. The name is thought to be of Irish origin, and to have the same root Laigin in Irish as the word Leinster...
in Gwynedd
Gwynedd
Gwynedd is a county in north-west Wales, named after the old Kingdom of Gwynedd. Although the second biggest in terms of geographical area, it is also one of the most sparsely populated...
, north-west Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
on 19 July 1984 at 06:56 UTC
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
(07:56 BST
British Summer Time
Western European Summer Time is a summer daylight saving time scheme, 1 hour ahead of Coordinated Universal Time. It is used in the following places:* the Canary Islands* Portugal * Ireland...
). It measured 5.4 on the Richter scale
Richter magnitude scale
The expression Richter magnitude scale refers to a number of ways to assign a single number to quantify the energy contained in an earthquake....
, and is the largest known onshore earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
to occur in the UK
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
since instrumental measurements began.
The effects were felt throughout Wales, most of England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
and parts of Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
and Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
. There were many reports of minor damage to chimneys and masonry throughout Wales and England, the biggest concentration of damage being in Liverpool
Liverpool
Liverpool is a city and metropolitan borough of Merseyside, England, along the eastern side of the Mersey Estuary. It was founded as a borough in 1207 and was granted city status in 1880...
, which is located around 65 miles north-east of the epicentre. Minor injuries were also reported in the areas surrounding the epicentral area, and rockslides occurred at Tremadog
Tremadog
Tremadog is a village on the outskirts of Porthmadog, in Gwynedd, north west Wales. It was a planned settlement, founded by William Madocks, who bought the land in 1798...
in Gwynedd.
It was followed by many aftershock
Aftershock
An aftershock is a smaller earthquake that occurs after a previous large earthquake, in the same area of the main shock. If an aftershock is larger than the main shock, the aftershock is redesignated as the main shock and the original main shock is redesignated as a foreshock...
s in the following months, the largest measuring 4.3 on the Richter scale, which itself was felt as far away as Dublin, in Ireland.