Scientists pinpoint cause of devastating 2011 Japan tsunami
Friday, December 6, 2013, 3:43 -
On March 11, 2011, a magnitude 9.0 earthquake struck northeastern Japan, triggering a massive tsunami seven metres high.
At the time, scientists said the monster wave was much larger than predicted. Now, it appears they have figured out why.
New papers published in the journal Science suggest the tsunami was caused by a thin layer of slippery, wet clay between two tectonic plates off the coast.
The fine layer of clay may have acted as a lubricant, causing the plates to shift past one another at a high speed, triggering the massive tsunami.
Last December, 27 scientists from 10 countries spent 50 days drilling into the sea floor near the site of the quake. Rock and sediment were analyzed to look for signs of previous earthquakes.
Researcher Christie Rowe told the CBC that the samples were "unlike any sediment material" she had ever come across, describing them as "very, very squishy, very slimy clay."
Scientists don't think the slippery clay causes more earthquake activity, but believe it is more efficient at creating tsunamis.
They say the study "concerning", given that the clay covers much of the northwest Pacific Ocean, meaning the area could be more tsunami-prone that previously thought.