# How Fast Does A Tsunami Travel?

**URL:** <https://boards.straightdope.com/t/how-fast-does-a-tsunami-travel/530655>\
**Category:** Factual Questions\
**Created:** [February 27, 2010, 4:59pm UTC](https://boards.straightdope.com/t/how-fast-does-a-tsunami-travel/530655 "2010-02-27T16:59:38Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![elucidator](https://avatars.discourse-cdn.com/v4/letter/e/8edcca/32.png) [@elucidator](https://boards.straightdope.com/u/elucidator)\
**Post date:** [February 27, 2010, 4:59pm UTC](https://boards.straightdope.com/t/how-fast-does-a-tsunami-travel/530655/1 "2010-02-27T16:59:38Z")

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Provoked by todays news of the Chilean earthquake…

Tsunami warnings are issued to Pacific inhabitants, for instance, Hawaii. Assuming the wave has a specific speed at which it travels, what is that speed, and what factors affect it, i.e., intensity of the earthquake, etc.

I would imagine that tidal waves all pretty much travel at the same speed, and vary only in the height of the wave, but I realize I don’t actually know squat. So, time to consult the Smartass Squad.

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**Author:** ![IAmNotSpartacus](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@IAmNotSpartacus](https://boards.straightdope.com/u/IAmNotSpartacus)\
**Post date:** [February 27, 2010, 5:02pm UTC](https://boards.straightdope.com/t/how-fast-does-a-tsunami-travel/530655/2 "2010-02-27T17:02:44Z")

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Speed will be affected by ocean depth.

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**Author:** ![DCnDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dcndc/32/2842_2.png) [@DCnDC](https://boards.straightdope.com/u/DCnDC)\
**Post date:** [February 27, 2010, 5:32pm UTC](https://boards.straightdope.com/t/how-fast-does-a-tsunami-travel/530655/3 "2010-02-27T17:32:35Z")

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> **[How Tsunamis Work](https://science.howstuffworks.com/nature/natural-disasters/tsunami1.htm)**
>
> Wave structure consists of a trough and a crest. Learn about wave structure and find out how the wave structure of a tsunami differs from a normal wave.

In the open ocean a tsunami can travel up to some 5-600mph depending on depth and topography, but upon approaching landfall will slow to around 30mph, give or take 5-10mph. At those speeds the Chile earthquake tsunami could reach Japan in about 24 hours. An identical event occurred back in 1960:

[http://www.drgeorgepc.com/Tsunami1960.html](http://www.drgeorgepc.com/Tsunami1960.html)

A large tsunami, a la 2004 will typically require \>6.75 earthquake or a large underwater volcanic event.

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**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\
**Post date:** [February 27, 2010, 5:36pm UTC](https://boards.straightdope.com/t/how-fast-does-a-tsunami-travel/530655/4 "2010-02-27T17:36:40Z")

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According to a couple of sites on Google, tsunamis can travel at 500 to 1000 kilometers per hour across the deep ocean, but slow as they enter shallower water.