Magnification of Tsunami Risks Due to Sea Level Rise Along the Eastern Coastline of Japan

Sea level rise is likely to increase the risks of inundation due to coastal hazards in the course of the 21st century. To understand how different sea level rise (SLR) scenarios will affect the disaster risk management of tsunamis in Japan, the authors applied the Probabilistic Tsunami Hazard Assessment (PTHA), using a logic tree approach, to the eastern coastline of Japan. Considering a similar generation zone as the 2011 Tohoku Earthquake and Tsunami, a number of tsunami propagation simulations were conducted. In the logic tree construction, different branches of magnitude ranges, positions of asperity, recurrence intervals, standard deviations of log-normal distribution and truncations of log-normal distribution were set. The results indicate that the maximum water levels at output points increased according to the different SLR scenarios that were considered. It was also found that the effects that SLR has on expected tsunami heights and 90% confidence intervals are nonlinear and could vary according to location. Such results highlighted the importance of considering the effects of SLR to improve emergency response capacity.