The prehistoric Atlantis in question was an area of land in the North Sea, between the UK and Scandinavia, known as Doggerland. During the last Ice Age, when sea levels were low, Doggerland provided a land bridge, traversed by migrants and settlers alike.
     Eventually, at the end of the Ice Age, sea levels begin to rise and Doggerland started to disappear, shrinking in size, with the remaining areas becoming marshy and waterlogged. Then, approximately 8,000 years ago the final killer blow was dealt.
     A team from Imperial College London (UK) have been carrying out computer simulations of a sub-sea landslide, known as the Storegga slide. This landslide was on the scale of 3,000 cubic kilometres of material and would have created a tsunami 5 metres high (much higher than the remains of Doggerland at that time). This would have effectively wiped out any remaining settlements, flora and fauna, with the remains of the land remaining permanently under water.
     "The impact on anyone who was living on Doggerland at the time would have been massive - comparable to the Japanese tsunami of 2011," said Dr Jon Hill from Imperial College London.

Edited from BBC News, The Independent (1 May 2014)