During the last glacial period much of the North Sea between Britain and Europe was dry land, roamed by mammoths and accompanying human hunters. We know this because the North Sea is fairly shallow in places and mammoth bones and spears are regularly brought up in the nets of fishermen. As the glaciation came to an end and the ice caps melted the waters encroached and Britain became an island. By 8200 years ago the North Sea was pretty much at its present extent, save for a large group of flat marshy islands at the southern end roughly the size of Wales, lying midway between Britain and Denmark. Doggerland, as these islands are known to archaeologists, was the last part to be submerged, and today form the shallows known to fishermen and the BBC shipping forecast as Dogger Bank.
Around the same time, something fairly catastrophic and unusual occurred off the coast of Norway; there was a huge subsea landslide (called the Storegga slide)—perhaps because of an earthquake or some other trigger almost 300 km of subsea coastline collapsed, abruptly dropping 3500 cubic km of sediments into the North Atlantic. The Shetlands and the Faroe Islands would have taken the full force of a tsunami wave about 30 metres high, and in Scotland it ran 80 km inland, where a layer of sediment can still be seen in numerous locations.
What a group from Imperial College, London, have now done is build a computer simulation of how the tsunami would have travelled across the Atlantic and down through the North Sea. It makes for scary viewing.
The wave would have still been 5 metres high when it hit Doggerland around 12 hours after the slide started, but unlike Scotland these low-lying islands would have been completely overrun. It is not known if Doggerland was still inhabited at the time it was hit, after all they were already rapidly shrinking marshy islands by then, but as Dr Jon Hill the lead researcher put it 'If you put a 5-metre wave towards Doggerland it would have been devastated.’
What's really scary is that the causes of the Storegga slide are not fully understood. It might have been triggered in some way by the removal of the ice sheet, or by an earthquake, or even by the release of subsea methane deposits.
Something to think about next time you're on a North Sea oil platform...