NUMERICAL SIMULATION FOR UNDERSTANDING OF THE OFFSHORE- DIRECTED SEDIMENT TRANSPORT BY 2011 TOHOKU-OKI TSUNAMI AT SOUTHERN PART OF THE SENDAI BAY

Abstract

 Validity and accuracy of numerical model of tsunami-induced sediment transport is the key to clarify the whole picture of the sediment transport by 2011 Tohoku-oki Tsunami, and to predict nearshore disasters by future tsunamis. Thus, verification of the numerical simulations based on the field data and its interpretations are essential to improve the numerical model.
 The numerical simulation of the 2011 Tsunami demonstrated that intensive tsunami sediment transport mainly occurred by the backwash on the shallow seafloor at southern part of the Sendai Bay. The simulations by medium- and coarse-grained sands are generally consistent with the transport process inferred from the field data by seafloor and subseafloor survey. In addition, the simulation supports the interpretation for increase, stagnant, and decrease of flow speed and suspended load on the seafloor that is derived from the grain-size analysis of a sediment core. The present research that verifies the interpretation of the sediment transport affected by the difference in grain size, represents new prospect for improvement of the sediment transport model.