The 2011 Japan tsunami, which killed up to 20,000 people and caused the partial meltdown of the Fukushima nuclear plant, was made worse by an underwater landslide, according to scientists.
Until now, the lethal waves have been blamed solely on the magnitude-nine earthquake which struck at sea, 43 miles east of the country's northern Tohoku peninsula.
But an international team, led by Professor Dave Tappin of NERC's British Geological Survey, say the earthquake can't explain the full extent of the waves.
'The earthquake alone cannot explain the height of the waves along the Sanriku coast of northern Honshu Island,' says Tappin. 'They were generated by a submarine landslide.'
According to Tappin, the research raises a 'big problem' for early-warning systems. Where the risk of landslides goes unrecognised, tsunamis generated by similar earthquakes could be badly underestimated.
It's well known that landslides can generate tsunamis on their own, and research on the Papua New Guinea event of 1998 showed that landsides triggered by small earthquakes could also produce devastating tsunamis.
But this research, presented at last week's Fall Meeting of the American Geophysical Union, is the first to recognise the significant contribution that underwater landslides can make to tsunamis generated by giant quakes.
Source: NewsOnJapan
