A shallow-flow model for the propagation of tsunamis over mobile boundaries

A recent revision of the catalogue of tsunamis in Portugal has shown that Tagus estuary has been affected by catastrophic tsunamis numerous times over the past two millennia. This justifies the modelling efforts aimed at quantifying potential inundation areas for present-day altimetry and bathymetry of Tagus estuary. The purpose of this work is to present a 2DH mathematical model applicable to discontinuous shallow flows over complex geometries such as tsunami propagation overland. The conceptual model and the discretization scheme are presented and validation tests are described. The propagation of a tsunami with the magnitude of that of 1755 is simulated for the bathymetric and altimetry conditions of present day Tagus estuary. The study shows that some locations of Tagus estuary are vulnerable to tsunami impacts, as they may register 1 to 2 m flow depths and velocities of 5 ms.