Wednesday 8 November 2017

Magnitude 3.7 Earthquake off the west coast of Norway.

The British Geological Survey recorded a Magnitude 3.7 Earthquake at a depth of 11 km, about 35 km west of the city of Bergen in Hordaland County, southern Norway, slightly after 9.45 am local time (slightly after 8.45 am GMT) on Tuesday 7 November 2017. There are no reports of any damage or injuries associated with this event (nor would they be expected of an event this size), though it was felt in the Bergen area.

The approximate location of the 7 November 2017 Norwegian coastal Earthquake. Google Maps.

Earthquakes are rare in Norway, and those that do occur tend to be s mall, which makes the causes hard to determine. The entire of Europe is being pushed eastward by the expansion of the Atlantic Ocean and northward by the impact of Africa from the south, though these are remote from the Kattegat. There are lesser areas of expansion beneath the North Sea and Rhine Valley, both of which will presumably have some effect on southern Scandinavia. 

Finally their is glacial rebound; until about 10 000 years ago much of northern Europe was covered by a thick layer of ice. This pushed the rocks of the lithosphere down into the underlying mantle, and now that the ice is gone these rocks are springing back up, albeit very slowly, a process which is not smooth as rocks tend to stick to one-another, and which therefore causes the occasional small Earth tremor.
 
(Top) Simplified diagram showing principle of glacial rebound. (Bottom) The extent of glaciation in Europe at the last glacial maximum. Wikipedia.
 
Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.
 
See also...

http://sciencythoughts.blogspot.co.uk/2016/08/lightning-kills-323-reindeer-in.htmlhttp://sciencythoughts.blogspot.co.uk/2016/05/thirteen-dead-after-helicopter-crashes.html
http://sciencythoughts.blogspot.co.uk/2015/12/magnitude-38-earthquake-off-west-coast.htmlhttp://sciencythoughts.blogspot.co.uk/2015/05/magnitude-36-earthquake-hjelmeland.html
http://sciencythoughts.blogspot.co.uk/2012/08/large-earthquake-near-jan-mayen-island.htmlhttp://sciencythoughts.blogspot.co.uk/2012/05/magnitude-62-earthquake-north-of-norway.html
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