The British Geological Survey recorded a Magnitude 2.5 Earthquake at a depth of 10 km, about 60 km offshore of the town of Florø in Sogn og Fjordane County, southern Norway, slightly before 7.10 am local time (slightly 6.10 am GMT) on Wednesday 23 May 2018. There are no reports of any damage or injuries associated with this event, though it is likely to have been felt locally.
The approximate location of the 23 May 2018 Norwegian coastal Earthquake. Google Maps.
Earthquakes are rare in Norway, and the waters between them, and those that do occur tend to be small, 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.
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