Was Britain’s great flood of 1607 a tsunami?

A one-off tsunami unleashing an irresistible force that left 2,000 dead or a powerful storm surge that caused a trail of devastating destruction around a coastline left vulnerable by inadequate defences?

That’s the question which has surrounded recent research on the Great Flood that was described as moving 'faster than a greyhound can run' when it hit Stuart Britain in 1607. Author Mike Hall revisits the conundrum in his new book The Severn Tsunami? The Story of Britain’s Greatest Natural Disaster. The book recounts how the brutal wave, over seven metres high, swept up the River Severn and flooded the lowland areas of South Wales, Gloucestershire, Somerset, and north Devon, killing thousands.

For centuries, those who survived called it an act of God, before modern scientific research began to delve into whether it was Britain’s first recorded tsunami. In order for a tsunami to occur, an earthquake has to happen below the seabed.

But if it was a tsunami, places including Brittany, Spain, Portugal and the west of Ireland should also have been affected, says Mr Hall. And though the evidence is not conclusive, Mr Hall believes the 1607 event was “probably” a storm surge...

But Mr Hall, from Redwick, Monmouthshire, admits that evidence that continues to support those who believe it was a tsunami comes from the 17th century chronicles and other written sources that tell of a “bright, sunny, cloudless day”. Conditions very far removed from those we would associate with a storm...

Professor Simon Haslett, of the University of Wales...believes the damage was caused by a tsunami, rather than high tides and severe storms.

The professor of physical geography has said descriptions in 17th century pamphlets of “huge and mighty hills of water” are more in keeping with a tsunami. He maintains there is evidence salt marshes were torn out of the Severn estuary in the early 17th century and only a tsunami would have the power to erode the coastline in this way. 

Source: Wales Online