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Tsunami Wave Speed Calculator

Work out tsunami wave speed instantly with clear inputs, formula shown and shareable results.

About Tsunami Wave Speed Calculator

A tsunami is a shallow-water wave even in the deep ocean because its wavelength dwarfs the depth, so its speed is sqrt(gd). At 4000 m that is 198 m/s, or 714 km/h - jetliner speed - crossing 1500 km in about 2.1 hours. In 10 m of water it slows to 9.9 m/s, and the energy piles up into height as it does so.

Formulas

Shallow-water wave speed

v = sqrt(g x depth)

Travel time

t = distance / v

Worked example

With the default values below, Tsunami Wave Speed Calculator returns Tsunami Propagation Speed of 198.06. Change any input above and every figure here is recalculated in your browser.

Inputs used

Ocean depthminimum 0 m
4,000 m
Distance to travelminimum 0 km
1,500 km

Results

Tsunami Propagation Speed
198.06 m/s
Same Speed In km/h
713.0
Time To Cover The Distance
2.10 h
Speed In 10 Metres Of Water
9.90 m/s

Step by step

  1. 1Values used
  2. 2Shallow-water wave speed
  3. 3Travel time
  4. 4Tsunami Propagation Speed= 198.06 m/s
  5. 5Same Speed In km/h= 713.0
  6. 6Time To Cover The Distance= 2.10 h
  7. 7Speed In 10 Metres Of Water= 9.90 m/s

Assumptions and limits

  • The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does a tsunami grow near shore?

Because slowing compresses the wave: energy flux is conserved, so as speed drops the amplitude rises through wave shoaling.

Why is a tsunami barely noticeable at sea?

In deep water its amplitude may be under a metre spread over a 200 km wavelength, so a ship rises and falls imperceptibly over minutes.

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