Devastating tsunami emphasize the vulnerability of low-lying islands and coasts. Our risk assessment for the three atolls of Tokelau uses computer simulations of tsunami generated by a series of regional and distant earthquakes to inform a community advisory of a threat from tsunami flooding. Great earthquakes off northeastern Japan pose a potential threat, with maximum wave heights >  1 m, but villages remain dry. Informative simulation studies can be achieved on atolls with only basic field data.

In this study, a response system is set up at harbors against unexpected tsunami attacks. The response system may contribute to mitigate natural disasters and provide guidelines for future disaster prevention researches.

The research investigates the tsunami hazard in the remote French territory of Wallis and Futuna, Southwest Pacific, using numerical computer modelling of tsunami generation, propagation and inundation. Wallis consists of the inhabited island of Uvéa that is surrounded by a lagoon delimited by a barrier reef, whereas Futuna and the island of Alofi form the Horn Archipelago located ca. 240 km east. Futuna and Alofi are surrounded by a narrow fringing reef and emerge from the North Fiji Transform.

The developed numerical inversion technique based on the least square inversion and a truncated SVD approach were applied to recovering the initial tsunami waveform. The method presented allows one to control the instability of the numerical solution. Analyzing the singular spectra of the matrix obtained during numerical calculations one can estimate the future inversion by a certain observational system that will allow offering more effective disposition for the registrators by precomputations.

The 1993 Hokkaido tsunami brought about a maximum wave run-up of 31.7m. To reproduce the extreme run-up height, a three-dimensional non-hydrostatic model has been locally applied with open boundary conditions supplied in an offline manner by a three-dimensional hydrostatic model. The diffraction of the tsunami wave primarily by islands was found to result in the extreme run-up height as in the laboratory simulation.

Tsunamis induced by rock slides constitute a severe hazard to coastal fjord communities. Fjords are narrow and rugged with steep slopes, and modeling the short-frequency and high-amplitude tsunamis in this environment is demanding. In the present paper, our ability to simulate tsunami propagation and run-up in fjords for typical wave characteristics of rock-slide-induced waves is demonstrated. The simulations are compared with unique lab test data for a fjord in 1:500 scale.