Virginia Toy of New Zealand's University of Otago participated in a project to drill into the subduction fault that slipped in 2011, generating a magnitude-9 earthquake and a tsunami that hit Japan's east coast.
Attempting to determine why there was such a large displacement of the fault, the researchers found there was near total release of stress in the crust above the fault plane when the 2011 earthquake occurred, China's officials Xinhua news agency reported Friday.
"This is significant because most earthquake faults only release a small portion (typically 10 percent) of the stress in the crust around them, not nearly 100 percent as in this case," Toy said.
The results suggest subduction zone faults in other locations, including around New Zealand, need to be more carefully studied, she said.
"If the materials in the fault planes are similar to those in the Japan Trench, it is likely they will also be very frictionally weak and therefore that we can also expect very large seafloor displacements when they slip," she said. "It means that we should be prepared for other similar subduction zones to generate very large tsunami."