Tsunami Wave Speed

This formula gives the speed of a tsunami when the wave travels in deep enough water that its wavelength is much larger than the ocean depth, so the whole water column moves together like a shallow-water wave. In that regime, gravity is the restoring force and the wave speed depends mainly on depth, not on wave height or wavelength. Deeper water lets the disturbance move faster because the pressure signal can involve a thicker layer of water, increasing the wave’s propagation speed.

Use this when estimating how fast a tsunami will travel across the open ocean from a known water depth, especially in hazard modelling or travel-time estimates. It is appropriate for long-wave tsunami motion in the deep ocean, not for breaking waves near shore.

• using the formula for coastal breaking waves instead of deep-ocean tsunami travel
• forgetting to convert depth into metres before calculating
• confusing wave speed with wave height, which this formula does not predict