Time since rupture00:00:00

Magnitude8.6

Source depth20 km

Seafloor uplift4.0 m

Sea-surface height

Flooded landInundation footprint

Inspector Hover over the map Read depth, wave speed c = √(g·h) and wavelength at any point.

Click or drag in the ocean to place the earthquake source

Tsunami Lab

A sudden seafloor uplift lifts the whole water column. The hump spreads as a long shallow-water wave, racing across the deep ocean, slowing and growing on the shelf, and finally flooding the coast.

Playback speed 12 min/s Magnitude (Mw) 8.6 Source depth 20 km Fault strike 0°

Display

Ring interval Cross-section line y = 600 km

Tide gauges live water level at each buoy

Event summary

Max height, open ocean– Max height, shelf (<100 m)– Max inundation depth– Highest run-up elevation– Flooded land area– Dominant wavelength / period– Solver–

How a tsunami works

Speed. A tsunami wavelength (100–300 km) is far longer than the ocean is deep, so it is a shallow-water wave: c = √(g·h), independent of wavelength. Over 4 km of water that is ≈ 200 m/s (710 km/h); over 10 m it is only 10 m/s.
Wavelength. The period T stays fixed as a wave travels, so λ = c·T. When c drops, the wave is squeezed: the crests bunch up and the wave train compresses.
Green’s law. Energy flux is conserved, so amplitude grows as H ∝ h^−1/4. A 0.5 m open-ocean wave in 4000 m of water reaches ≈ 2.2 m in 10 m of water, before bays, funnels and run-up amplify it further.
Run-up. With the nonlinear terms on, the solver tracks a moving shoreline: cells wet and dry as the water advances, so you see inundation depth and the farthest reach.

Staggered-grid (Arakawa C) forward–backward finite-difference solution of the 2-D shallow-water equations, 400 × 250 cells at 5 km, Manning friction, radiating + sponge boundaries. Source: Gaussian seafloor dipole scaled by Wells–Coppersmith rupture dimensions. Idealised bathymetry; no dispersion, tides or sediment. Not for hazard assessment.