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What causes a tsunami?

Tsunami – derived from Japanese words harbour (tsu) and wave (nami) — is defined as a series of waves created when a water body is displaced on a huge scale largely because of underwater earthquakes, volcanic eruptions or landslides. Meteorite impact too has the potential to trigger a tsunami.

Which are the worst tsunamis?

The 2004 tsunami, which claimed more than 2.5 lakh lives, was one of the worst in recorded history. Japan has recorded more than 190 tsunamis in the last few centuries.

*1755 — In Lisbon, people who survived a quake rushed to the sea front for safety but were killed by the tsunami. Thousands perished. 
*1960 — Chilean tsunami, caused by a massive 9.3 strong earthquake, killed 3000.
*1976 — Moro Gulf tsunami in Philippines killed 5000.

Can tsunamis be predicted?

Tsunamis cannot be prevented or predicted, but there are some warning signs and systems are being developed to reduce the damage.

What are the signs?

In instances where the leading edge of the tsunami wave is its trough, the sea will recede from the coast half of the wave's period before the wave's arrival. If the slope is shallow, this recession can exceed many hundreds of metres. People unaware of the danger may stay back due to curiosity, or for collecting fish from the exposed seabed.