Energy Grade Line Analysis of Tsunami run-up on the Sendai Plain after the 2011 Tohoku earthquake

Energy Grade Line Analysis (EGLA) of tsunami run-up has been proposed as a simple tool to predict inundation heights and tsunami loads. A large database of more than 500 inundation measurements collected on the Sendai Plain on the east coast of Japan after the Tohoku earthquake of 2011 provided the writers the opportunity to evaluate the accuracy of the general EGLA method and to make adjustments to fit the model to the Sendai Plain. Refinements to the EGLA model included a correction for the influence of large linear topographic obstructions on tsunami flows in order to achieve better agreement with measured inundation heights. The study illustrates that inundation height predictions are sensitive to the choice of Froude number parameter and land use roughness coefficients. An important outcome of this study is a site-specific tool for probabilistic prediction of inundation heights over the Sendai Plain that is of value for tsunami counter measure planning including design of tsunami resistant structures.