Japan Quake Raises Shaking Risk Elsewhere in Country

OurAmazingPlanet
Wed, 25 May 2011

Map showing the 11 March 2011 magnitude 9.0 off Tohoku mainshock and 166 aftershocks of magnitude 5.5 and greater until May 20. Warmer color indicates more recent events. Larger symbol indicates greater quake magnitude.

The massive 9.0 magnitude earthquake that devastated Japan in March built up stress on other faults in the country, putting some areas, including Tokyo, at risk of aftershocks and even new main shocks over the next few years, scientists have found.

After studying data from Japan's extensive seismic network, researchers from the Woods Hole Oceanographic Institution (WHOI), Kyoto University and the U.S. Geological Survey (USGS) have identified several areas at risk from the quake, Japan's largest ever, which already has triggered a large number of aftershocks.

Data from the Tohoku earthquake on March 11 has brought scientists a small step closer to a better assessment of future seismic risk in specific regions, said Shinji Toda of Kyoto University, a lead author of the study.

"Even though we cannot forecast precisely, we can explain the mechanisms involved in such quakes to the public," he said. Still, he added, the findings do bring scientists "a little bit closer" to being able to forecast aftershocks.