Analytical solution for time-dependent shoreline position response to the tectonic recovery process in the Sendai Plain, Japan, after the 2011 Great East Japan Earthquake.

The 2011 Great East Japan Earthquake on March 11, 2011 triggered not only giant tsunami waves, but also caused significant land subsidence followed by land rise in the Sendai Coastal Plain areas. These impacts resulted in severe damages to the coastal infrastructure and induced coastal morphology changes along Japan's northeast coast. It was observed that the maximum downward deformation in the Sendai Coastal Plain was initially about - 0.3 m. Immediately after the earthquake, the land started to rise and it has already recovered back to its original position at some locations after 10 years. Thus, the high-quality measured beach profile data sets after the 2011 Tohoku Earthquake are valuable for exploring the impact of sea level rise (SLR) on shoreline position evolution, since the bed level change is inversely related to the sea level rise process. The data also provide a unique opportunity to evaluate the Equilibrium Beach Profile (EBP) theory and validate the Bruun concept. In the present study, a new simple analytical solution for time-dependent shoreline position response to the tectonic recovery process is developed based on the convolution method. The model results are able to predict the time-dependent shoreline evolution, including the maximum potential response and the characteristic erosion time scale at which the profile evolves towards a new equilibrium state. • New analytical solutions were developed based on the convolution method, assuming that the beach profile functions as a linear-dynamic system. • The co-seismic subsidence resulted in erosion, while the post-seismic land level rise rates resulted in beach recovery process in the Sendai Coastal Plain. • High-quality measured beach profile data sets after the 2011 Tohoku Earthquake are valuable for exploring the impact of sea level rise (SLR) on shoreline position evolution. • Both the convolution method and Bruun Rule provided reasonable estimates of the maximum erosion response due to sea level rise. [ABSTRACT FROM AUTHOR]