Could the magnitude of the 3/11 disaster have been reduced by ecological planning? A retrospective multi-hazard risk assessment through map overlay

•Japan’s 3/11 disaster could have been reduced through ecological planning.•A 1980 environmental inventory largely predicted areas impacted by 3/11 disaster.•Japan’s most recent risk mapping fails to indicate the 3/11 disaster impacted areas.•Map overlay can be instrumental for multi-hazard risk assessment.•Its effectiveness requires open, integrated and comprehensive risk information.