A Tsunami Is Not a Tidal Wave
A tsunami is a series of ocean waves caused by displacement of water. It has nothing to do with tides, and the Japanese name explains why the old term was wrong.
A tsunami is a series of waves caused by a sudden displacement of water, usually by an undersea earthquake. The old English name, *tidal wave*, is wrong: tides are caused by the moon and sun, and a tsunami by geology. The Japanese name means harbour wave, because ships at sea often noticed nothing while the harbour was destroyed.
- A series of waves from displaced water. *A tsunami warning.*
- An overwhelming surge (figurative). *A tsunami of applications.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | tsunami | A destructive tsunami. |
| Plural | tsunamis | Recorded tsunamis. |
| Related | seismic | Seismic activity. |
| Related | run-up | The run-up height. |
| Old term | tidal wave | The obsolete tidal wave. |
How it is used in a sentence
- A tsunami warning was issued for the coast.Emergency management.
- In deep water the wave is barely noticeable.It grows on reaching shallow water.
- The sea withdrawing is a warning sign.Move inland and uphill immediately.
Tsunami facts
- Speed — up to 800 km/h in deep ocean, comparable to a jet
- Wave train — a series, and the first is often not the largest
- Drawback — the sea retreating before the wave arrives
- Run-up — how high the water climbs on land
- Warning systems — sea-floor pressure sensors and buoys
From Japanese *tsunami*, from *tsu*, harbour, and *nami*, wave. English adopted it widely after the Indian Ocean disaster of 2004, replacing tidal wave.
Why is *tidal wave* wrong?
Because tsunamis are not caused by tides. They are caused by displacement of water, usually by earthquakes, landslides or volcanic activity.
What should you do if the sea withdraws suddenly?
Move inland and to high ground immediately. Drawback is a recognised sign that a tsunami wave is approaching.