A huge tsunami that swept through northern Europe more than 8,000 years ago may have killed off Stone Age inhabitants in northern Britain, according to a new study. This event, known as the Storegga tsunami, coincided with a sudden decline in the local population, although this decline had not previously been associated with the disaster.

The results of the study were published in the Journal of Quaternary Science.

During the Mesolithic, or Middle Stone Age, population of northern Britain was small, with approximately 1,000 people estimated to inhabit the region. Most of them lived in small coastal settlements that were in the path of huge tidal waves.

Archaeological evidence shows that around 8,200 years ago the number of human settlements in northwestern Europe suddenly declined. This is likely due to the gradual decline in temperatures across the continent, but some researchers believe that coastal communities may not have been affected by this climate change.

Interestingly, the Storegga tsunami coincides with this massive population decline that occurred between 8120 and 8175 years ago. The event, caused by a huge underwater collapse off the coast of Norway, caused huge waves over 20 meters high to hit the Shetland Islands, located north of mainland Scotland.

In the south, in northern England, waves reached heights of 3 to 6 meters. To find out whether the tsunami could have wiped out local populations, the researchers created a computer model of the wave at an important Mesolithic site called Howick in Northumberland, northeast England.

Sediments dating back to around the time of the tsunami were found here, indicating that the site may have been flooded during the disaster. However, these deposits are primarily composed of coarse gravels, as opposed to the fine sandy deposits typical of tsunamis. This caused some controversy as to whether the tsunami reached Howik or not.

The researchers ran wave simulations under two different sea level scenarios and found that in both cases the tsunami did not reach Hawick unless it occurred at high tide.

“Tidal forcing on the model increased the inundation area, with the initial wave inundating sediments at Howick,” they explained.

“Moreover, the resulting wave was strong enough to transport coarse gravel,” indicating that these deposits may have been generated by a tsunami.

If this were true, the consequences would be catastrophic: “At Howick, mortality estimates varied, but within the resource-rich tidal zone they were as high as 100 percent.” In addition to killing everyone affected, the wave would also destroy food supplies, leading to massive population declines across northwestern Europe.

“This suggests that the tsunami may have contributed to the estimated population decline in northern Britain in the period following the tsunami event 8,200 years ago,” the authors concluded.