Simulating The Tsunami

The tsunami propagation was simulated using the advanced numerical model MIKE21. This code describes the free surface flow and has proven to yield accurate tsunami model results. The model was set up as a nested grid model allowing a stepwise model refinement approaching the shoreline.

The largest grid has a resolution of 810 m. It covers Japan and part of the Pacific Ocean, as shown in Figure 4 below. The model is refined close to the Japan shoreline by using two grids with a resolution of 270 m and 90 m. This allows detailed modelling of the propagation of the tsunami wave from the deep ocean towards land.

The bathymetry grids have been interpolated based on available navigation charts (from MIKE C-Map) and topography data (from USGS Shuttle Radar Topography Mission, SRTM).

usgs

Figure 1:Model bathymetry used for tsunami modelling. (Red boxes indicate the location of nested grids)

In this model, the propagation of the tsunami wave was initiated by a water level map, obtained as described in Tsunami Generation section.