Tsunami v Tidal Wave

16 October 2009

There is only one clear thing in the debate about the terms "tsunami" and "tidal wave" - confusion.

Fundamentally, a tsunami is generated by any undersea disturbance, such as an earthquake, submarine landslide or even an asteroid impact. Any one of these events moves the water column over the entire depth of the ocean, rather than just the surface, as is the case with wind-driven, conventional waves.

Recognised as the international signature for tsunami, this painting is by Japanese artists, Katsushika Hokusai - www.katsushikahokusai.org

Recognised as the international
signature for tsunami, this painting
is by Japanese artist,
Katsushika Hokusai

In contrast, a tidal wave is a phenomena resulting from the influence of the sun and the moon. It is generated when an incoming tide is funnelled into a narrow estuary or river mouth, causing its leading edge to form a wave or waves which travel up a narrow bay or river against the direction of the current.

There has been confusion also about the word tsunami which translates as 'harbour wave'.

The word tsunami was derived from 'tsu' meaning harbour and 'nami' meaning wave. They were combined because Japanese fishermen who were out at sea fishing in deep water, where there was little or no visible effect, returned to find their home village devastated, creating the belief that tsunami occurred only in harbours and close inshore.

The Senior Lecturer in Asian Studies and Japanese Linguistics at the Australian National University, Dr Shunichi Ishihara, advised that Japanese does not include the plural of nouns in its language, so the term "tsunami" is a singular, plural and collective noun.

Dr Ishihara says that, like another Japanese word describing weather, typhoon, tsunami has no plural in the same way the English example of a single sheep, two sheep and a mob of sheep is singular, plural and collective.

Topic contact: media@ga.gov.au Last updated: October 4, 2013