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Destructive tsunamis can destroy coastal structures and move huge amounts of tsunami debris. Our current understanding of motion of tsunami debris in tsunami flows is limited. In this paper, we present a preliminary laboratory study of motion of model debris under the action of solitary waves running up a beach. The difference between the waterline of maximum inundation and the final position of debris was examined under various conditions. Effects of solitary wave height, water depth, and the distance of debris source to the shoreline on the maximum inundation, the debris limit, and the final position of debris were examined. In general, the final positions of the debris are different from the waterline at maximum inundation and there is a low possibility that a large amount of debris can be carried by retreating water offshore into the sea. [ABSTRACT FROM AUTHOR]

In contrast to the efforts made to develop hydrodynamic models for large-scale tsunami propagation and run-up, little has been done to develop, test, and validate sediment transport models used to simulate tsunami-induced sediment movement. In this study, the performances of six widely-used sediment transport formulas are evaluated through case studies using an open source code XBeach, which is based on 2D depth-averaged nonlinear shallow water equations. Another open source code, Delft3D, is also used to see to what extent XBeach can give reliable results. The benchmarks used for case studies include three laboratory experiments and one field observation from a post-tsunami field survey conducted after the 2004 Indian tsunami. Our results show that most of the surveyed sediment transport formulas can give good results for laboratory-scale problems, but for real-scale problems, all six formulas failed to produce good results compared to those found in laboratory conditions. For laboratory-scale problems, both XBeach and Delft3D can predict satisfactory results with properly-chosen model parameters. For real tsunamis, high suspended sediment concentration may occur, and density stratification and hindered settling effect play an important role; therefore, Delft3D, with both hindered settling and density stratification being considered, may perform better than XBeach. The findings reported here will be useful for researchers and practitioners working on tsunami hazard mitigation. [ABSTRACT FROM AUTHOR]

Some challenging issues in tsunami disaster mitigation and risk management are raised at the AIWEST-DR2011 in Conjunction with SCSTW-4. Currently there is no enough attention given to potential tsunamis in South China Sea due to the lack of data for historic tsunamis in the area, therefore there is a need to have a joint effort among the countries bordering the South China Sea to collect scientific evidence of historic tsunamis along the border of the South China Sea. [ABSTRACT FROM AUTHOR]

The article presents an introduction to this issue of the journal that covers a wide range of topics related to tsunami generation, propagation and tsunami hazard mitigation.

Submarine landslides are one of the major causes of tsunamis but less understood due to complicated dynamics involved and the lack of observational data. In this study, the collapse of a submerged granular column is used as an idealized submarine landslide model. A three-phase (solid–liquid–gas) continuum model is used to study the effect of the column’s initial packing on the collapse process and the resultant waves. Numerical simulations reveal that the initial packing can have significant effect on the duration of the collapse process and the characteristics of the resultant waves. Pore pressure, velocity field of the fluid phase, the volume of the sliding granular mass, and the sliding velocity are calculated and used to understand the effects of initial packing condition. Our results show that it is important to consider the initial packing effects in numerical simulations of submarine landslides and the resultant waves. Our result also show that the large vortex generated by the moving front of the granular flow can affect the form of the waves generated by the landslide. [ABSTRACT FROM AUTHOR]

Depth-integrated wave models are widely used for simulating large-scale propagation of landslide tsunamis, with the generation of tsunami being simulated separately by various generation models to provide the required initial conditions. For a given problem, the selection of a proper tsunami generation model is an important aspect for tsunami hazard analysis. The generation of tsunamis by submarine or subaerial landslides is a transient multiphase process which involves important fine-scale physics. Depth-integrated generation models, while relatively easy to use, cannot simulate these fine-scale physics. Depth-resolved generation models can overcome the shortcomings of depth-integrated generation models but are computationally demanding. This paper first reviews existing depth-integrated generation models to show the need for depth-resolved generation models. Four classes of depth-resolved generation models are reviewed: computational fluid dynamics (CFD) models, approaches coupling CFD and discrete element method, multiphase flow models, and meshless particle models. Multiphase flow models, which are relatively new, can consider complex interactions between landslide materials and its surrounding fluids. Meshless particle models are appealing for simulating landslide tsunamis because of their convenience to deal with the violent motion of the water surface and ability to run on graphics processing units. The main strengths, weaknesses, and future research directions of the reviewed models are briefly discussed. The literature reviewed, which is by no means complete, aims to provide researchers updated and practical guidelines on numerical modeling techniques for simulating the generation process of landslide tsunamis. [ABSTRACT FROM AUTHOR]