Example Presets
Selecting a preset fills the inputs and immediately updates the results and graphs.
Inputs
Advanced Settings
Results
| Wave Speed (m/s) | — |
|---|---|
| Arrival Time (sec) | — |
| Arrival Time (hours) | — |
| Wave Speed (km/h) | — |
|---|---|
| Wave Speed (m/s) | — |
| Required Wave Speed (km/h) | — |
|---|---|
| Required Wave Speed (m/s) | — |
Graphs
Depth → Wave Speed (c=√(gh))
Distance → Arrival Time (Mode A)
Assumptions and Cautions
Formula used
Using the shallow-water wave approximation, wave speed is c = √(g h) and arrival time is t = d / c.
Where h is the average water depth (m), d is distance (m), and g is gravity (m/s²).
Prerequisites and Limitations
- Assumes constant average water depth.
- Does not consider refraction/reflection due to seafloor topography, or coastal shallow-water deformation/run-up.
- Actual tsunami arrival times can vary significantly from these estimates.
Frequently asked questions
Why is the wave faster in deeper water?
Under the shallow-water approximation, tsunami speed is proportional to sqrt(g h). Greater average depth increases the wave speed, even when the wavelength is much longer than the local depth.
How should I choose the average depth?
Use a representative average depth for the path you are comparing. Real bathymetry changes along the route, so a more serious study would split the path into segments instead of relying on one depth value.
Can I use this for disaster response decisions?
No. This page is for classroom use and rough scenario checks only. Always rely on official warning systems, local authorities, and real-time hazard guidance for operational decisions.
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