ABSTRACT:

A numerical model based on the mild slope equation is applied to reproduce the propagation of small amplitude transient waves over mildly sloped sea bed. The model is suitable to reproduce the tsunami far field propagation. In the present research the waves are generated by a forcing term included in the mild slope equation that represents the effects of a submerged landslide on the fluid. The comparison with laboratory experiments is used to test the model accuracy in the reproduction of complex three dimensional tsunami generation scenarios. A large geographical scale application of the model to a possible tsunami scenario in the South Tyrrhenian Sea (Italy) around the Aeolian archipelago is here presented.

INTRODUCTION

Tsunami is long water wave generated by sudden disturbances of the sea floor or sea water surface, which is usually caused by earthquakes, landslides or volcanic eruptions. The tragic consequences of the tsunami occurred on the 26th December 2004 in the Indian Ocean and the recent 11th March 2011 Japanese tsunami, involved the scientific community to develop models able to reproduce the tsunami generation and their evolution, with the aim of building Tsunami Early Warning Systems. A single model is not able to treat adequately the generation, propagation and inundation phase of tsunami scenarios, because it can not be at the same time accurate and computational efficient. The tsunami generation requires most of the times the solution of the full three dimensional equations of the hydrodynamics (Grilli et al., 2002; Liu et al., 2005), in order to accurately reproduce the complex sea floor motion and therefore the consequent wave field. When modelling the tsunami generation are important the nonlinear terms, which allow the reproduction of waves with a wave height of the same order of the water depth.

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