Tsunami mitigation in Japan after the 2011 Tōhoku Tsunami

Since the Great East Japan Earthquake and the following Tōhoku Tsunami on March 11th, 2011, Japan has been facing a great challenge of the long-term and costly reconstruction of the impacted Tōhoku Coast, particularly in Iwate, Miyagi and Fukushima Prefectures, where the highest damage ratio was documented. The development of the recovery plans and the new tsunami mitigation strategies, aiming at more efficient protection from such future natural disasters, required in the first step revision of the performance and the efficiency of the tsunami countermeasures employed so far, consideration of the lessons learned from the reconstruction processes after past tsunami disasters as well as adjustment to specific regional conditions (e.g. society aging, diminishing population ratio, land availability, reconstruction visions preferred by local communities). The recovery policies established by the Government of Japan after the 2011 Tōhoku Tsunami promote a combination of three key countermeasures for the reduction of future tsunami risk, namely structural/non-structural coastal protection facilities (under particular consideration of the contribution of green coastal belts), land use regulations and emergency management. The reconstruction policy is presented in this paper with particular attention paid to the planned or already introduced structural/non-structural tsunami countermeasures (such as sea dikes, seawalls, coastal forests, embankments) and land use planning.