By Amanda Ruggeri
Some 8,000 years ago, a tsunami with a run-up height of up to 25m swept Scottish islands and the coastline at 80mph. It may have been caused by climate change. Could it happen again?
It was an autumn day in the Shetland Islands of Scotland. Perhaps fishing boats were hauling in catch; maybe children were playing on the beach. Then it came in: a wall of water reaching a height of 25m above normal sea level at some points, high enough to top a seven-storey building. Travelling at a speed of some 35 metres per second (80mph) the wave might as well have been cement.
But unlike the Indian Ocean tsunami in 2006, there were no cameras to record the devastation, no internet to spread the news. Instead, when the water receded, it left behind only imprints on the landscape which would remain undiscovered for another 8,000 years.
Today, geologists, palaeontologists and archaeologists are working to piece together exactly what happened, what its effects were – and how likely a similar event is to occur again.
The tsunami that ripped across the North Sea around 6200BC, steamrolling coastlines from Norway to Scotland, resulted from the sudden collapse of some 180 miles (290km) of the continental shelf near Norway. Displacing some 3,000 cubic kilometres of sediment, the Storegga slide’s impact was felt far beyond Scotland’s shores. The resulting wave reached as far as Greenland, says Dr Jon Hill of Imperial College London in the UK.
The Storegga slide was the largest submarine slide ever known to have produced a tsunami
Even today, it is the third-largest submarine slide we know of in the world and the largest known to have produced a tsunami, says Hill. But it was also just one in a series of enormous events and rapid changes that defined the end of Earth’s last Ice Age, which lasted from 110,000 until about 12,000 years ago.
“This is the period when the world really changes,” says University of Bradford archaeologist Vincent Gaffney. “It’s the formation of the modern world, physically and culturally.”
At its most glaciated point, in the northern hemisphere ice covered all of present-day Canada and the northern United States, as well as much of Asia, Russia, northern Europe and Britain. Then came a period of warming about 20,000 years ago. The reasons for this are still debated, but there is growing evidence that warming from seasonal changes in solar energy may have been exacerbated by a naturally occurring rise in atmospheric greenhouse gases.