The Kuril Biocomplexity Project, an interdisciplinary team of US, Japanese and Russian scholars and students, surveyed the islands’ coastlines in the summer of 2006, just before two tsunami events – in November 2006 and January 2007 – during which waves up to 21 metres in height transformed their field site.

The team returned in 2007 to a drastically altered landscape. ‘The year before, it had been completely covered with vegetation, and there were ridges closer to the shore that had been completely removed when we returned,’ said University of Washington doctoral student Breanyn MacInnes, a member of the Kuril Biocomplexity Project.

A report of the findings, published in Geology, documents losses of up to 200 cubic metres of sediment per metre of width due to tsunami-induced erosion. In some places, erosion exceeded deposition by a factor of 50.

‘There are a lot of papers that describe erosion but they can’t really quantify it,’ MacInnes said. ‘Our study is the first to say: “This much sand was removed from the coast”.’

According to the report, while the extent of erosion depends on pre-tsunami topography – erosion was so dominant in the Kuril Islands because the steep incline of the coastlines accelerated tsunami outflow – it’s also related to the force of the wave, and to other factors, notably human activity. Any human disturbance, even just a fencepost, resulted in deeper erosion. 

Puffin O’Hanlon
January 2010