The role of tsunami engineering in building resilient communities and issues to be improved after the GEJE

Abstract

Twenty five years have passed since the Tsunami Engineering Laboratory (TEL) was founded in 1991 after the re-establishment of the Disaster Research Group at Tohoku University, Japan. The TEL contributes to the safety of society and coastal communities by improving tsunami knowledge and technology and reducing damage, particularly in tsunami-prone regions. In 2010, the Japanese government reported an earthquake and tsunami probability of 99 % within 30 years at Miyagi in the Tohoku region. The TEL initiated a collaboration between residents, the local government and experts regarding tsunami engineering, forming the group who established countermeasures such as evacuation drills based on hazard maps, disaster planning, structural construction countermeasures and offshore tsunami observations using GPS sensors for the targeting earthquake and tsunami. Nevertheless, eastern Japan, particularly the Tohoku region, was hit by a massive M = 9.0 earthquake in 2011. The earthquake named the 2011 Great East Japan Earthquake (GEJE) generate a huge tsunami that caused large-scale damage to the eastern coast of Japan and resulted in an inundation area of more than 500 km2 due to destructive wave forces. The Sanriku area was considered to be well prepared for tsunami disasters based on past damage experiences. However, following the 2011 tsunami, several issues need to be addressed. Researchers must determine why the large destruction occurred, what unrecognized factors contributed to the high vulnerability of the exposed area that must be reconstructed, and how the tsunami risk can be reduced in each region in the future. Reconstruction safety levels 1 and 2, which include comprehensive countermeasures related to creating tsunami-resilient communities, are just one example discussed in this study. The findings and issues also noted in this study will be valuable in improving future damage assessments in other high-risk areas throughout Japan such as the Nankai trough, and other tsunami-exposed coastal areas in the world.