Wide swaths of the Pacific coastline stretching from Honshu to Shikoku may be hit by tsunami over 20 meters high if a newly feared megaquake occurs in the Nankai Trough, a Cabinet Office panel warned Saturday.
The new warning comes after the panel revised its 2003 estimate to reflect new findings from the March 2011 earthquake and tsunami that devastated the Tohoku region's coastline last year.
The 2003 report said no areas would see tsunami higher than 20 meters. The updated report is based on the assumption that the earthquake will have a magnitude of 9.0.