TsunamiNonlinear shallow-water waves over bathymetry (2D, staggered grid)

Undersea earthquake

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Coastal impact

First arrival–
Max run-up–
Inland reach–
Flooded area–

Tide gauges (drag on map, double-click to remove)

What to look for

  • Speed = √(g·depth). A tsunami is a long wave: it feels the whole water column, so it races across the deep ocean and crawls on the shelf.
  • Shoaling: as the wave slows its wavelength shrinks and (Green's law, H ∝ d−1/4) its height grows. See the cross-section.
  • Refraction: fronts bend toward shallow water; islands and seamounts focus and shadow energy; the headland and bay concentrate it.
  • Leading trough (dark) arrives first when the coast is on the subsided side: the sea draws back before the surge.
  • Gauges: compare offshore (small, fast, short) with bay-head (large, long-lasting resonance).
Depth 4000 m198 m/s · 713 km/h
Depth 1000 m99 m/s · 356 km/h
Depth 100 m31 m/s · 113 km/h
Depth 10 m9.9 m/s · 36 km/h