Sciency Thoughts: Dumfries and Galloway

Showing posts with label Dumfries and Galloway. Show all posts

Sunday, 23 September 2018

Atlantic Storm Ali kills two in Ireland.

Two people died in different parts of Ireland and several people were injured across Ireland and the UK as Atlantic Storm Ali swept in from the Atlantic on Wednesday 19 September 2018. In County Galway, in the Republic of Ireland, Swiss tourist Elvira Ferrari, 56, was killed when the caravan she was staying in was swept off a cliff by high winds, while in County Armagh Mathew Campbell, 24, was killed when a falling tree struck him and a companion, who was also injured. In Scotland several children were injured when they were struck by flying debris in Dumfries and Galloway, un un-named person was injered when blown over by high winds in Dundee, a Highland Main Line was derailed after striking branches fallen from a tree and a cruise ship slipped its moorings in Greenock, Inverclyde. Both incidents led to passengers and crew needing to be evacuated, though neither resulted in any casualties. In England a woman recieved serious injuries after her car was struck by a falling tree in Crewe, Cheshire.

The remains of a caravan swept off a cliff in County Galway on Wednesday 19 September 2018. Niall Carson/PA.

Niall Carson/PA

Read more: https://metro.co.uk/2018/09/20/tributes-paid-to-swiss-tourist-killed-in-ireland-after-caravan-blown-off-cliff-during-storm-ali-7963939/?ito=cbshare
Twitter: https://twitter.com/MetroUK | Facebook: https://www.facebook.com/MetroUK/N

Ocean storms form due to heating of air over the sea in tropical zones. As the air is heated the the air pressure drops and the air rises, causing new air to rush in from outside the forming storm zone. If this zone is sufficiently large, then it will be influenced by the Coriolis Effect, which loosely speaking means the winds closer to the equator will be faster than those further away, causing the storm to rotate, clockwise in the northern hemisphere and anticlockwise in the southern hemisphere.

Whilst the high winds associated these storms is extremely dangerous, the real danger from such storms is often the flooding. Each millibar drop in air pressure can lead to a 1 cm rise in sea level, and large storms can be accompanied by storm surges several meters high. This tends to be accompanied by high levels of rainfall, caused by water picked up by the storm while still at sea, which can lead to flooding, swollen rivers and landslides; which occur when waterlogged soils on hill slopes lose their cohesion and slump downwards, over whatever happens to be in their path.

Saturday, 2 December 2017

Magnitude 1.1 Earthquake near Dumfries, Scotland.

The British Geological Survey recorded a Magnitude 1.1 Earthquake at a depth of about 2 km roughly 10 km to the north of the town of Dumfries in Dumfries and Galloway, Scotland, slightly after 0.30 am GMT on Thursday 28 November 2017. This was not a major event, and presented no threat to human life or property, but may have been felt locally.

The approximate location of the 28 November 2017 Dumfries Earthquake. Google Maps.

Earthquakes become more common as you travel north and west in Great Britain, with the west coast of Scotland being the most quake-prone part of the island and the northwest of Wales being more prone to quakes than the rest of Wales or most of England.

The precise cause of Earthquakes in the UK can be hard to determine; the country is not close to any obvious single cause of such activity such as a plate margin, but is subject to tectonic pressures from several different sources, with most quakes probably being the result of the interplay between these forces.

Britain is being pushed to the east by the expansion of the Atlantic Ocean and to the north by the impact of Africa into Europe from the south. It is also affected by lesser areas of tectonic spreading beneath the North Sea, Rhine Valley and Bay of Biscay. Finally the country is subject to glacial rebound; until about 10 000 years ago much of the north of the country was covered by a thick layer of glacial ice (this is believed to have been thickest on the west coast of Scotland), pushing the rocks of the British lithosphere down into the underlying mantle. This ice is now gone, and the rocks are springing (slowly) back into their original position, causing the occasional Earthquake in the process.

(Top) Simplified diagram showing principle of glacial rebound. Wikipedia. (Bottom) Map showing the rate of glacial rebound in various parts of the UK. Note that some parts of England and Wales show negative values, these areas are being pushed down slightly by uplift in Scotland, as the entire landmass is quite rigid and acts a bit like a see-saw. Climate North East.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. If you felt this quake, or were in the area but did not (which is also useful information) then you can report it to the British Geological Survey here.

See also...

http://sciencythoughts.blogspot.co.uk/2017/10/magnitude-12-earthquake-near-ringford.html

http://sciencythoughts.blogspot.co.uk/2017/04/magnitude-17-earthquake-in-cumbria.html

http://sciencythoughts.blogspot.co.uk/2016/05/magnitude-13-earthquake-in-cumbria.html

http://sciencythoughts.blogspot.co.uk/2015/12/magnitude-11-earthquake-in-cumbria.html

http://sciencythoughts.blogspot.co.uk/2015/10/magnitude-14-earthquake-near-peebles.html

http://sciencythoughts.blogspot.co.uk/2015/10/magnitude-12-earthquake-in-dumfries-and.html

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Sunday, 1 October 2017

Magnitude 1.2 Earthquake near Ringford in Dumfries and Galloway, Scotland.

The British Geological Survey recorded a Magnitude 1.2 Earthquake at a depth of about 7 km roughly 2 km to the northeast of the village of Ringford in Dumfries and Galloway, Scotland, slightly before 2.40 am British Summertime (slightly before 1.40 am GMT) on Wednesday 27 September 2017. This was not a major event, and presented no threat to human life or property, but people have reported feeling it in the town of Dalbeattie, about 10 km to the east.