AUSTIN, Texas, April 7 (UPI) -- U.S. scientists say they've found last year's 8.1 magnitude Indonesian earthquake broke through a geological area thought to protect against earthquakes.
The April 1, 2007, earthquake and tsunami in the Solomon Islands area killed 52 people and displaced more than 6,000 others.
University of Texas at Austin geoscientists said their study means other sites, such as the Cascadia Subduction Zone in northwestern North America, might produce more severe earthquakes than thought.
The researchers said the rupture started on the Pacific sea floor near a spot where two of Earth's tectonic plates are subducting, or diving below, a third plate.
The boundary between those plates, called Simbo Ridge, was thought to work as a barrier to the propagation of a rupture, the researchers said. But the boundary did not stop the rupture from spreading from one plate to the other.
"What our work shows is that this is a barrier, but not a reliable one," said Fred Taylor, who led the study.
The findings are detailed in the journal Nature Geoscience.