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The notion of a taller-than-skyscraper, so called "megatsunami" is not new - with the often-reported 524m (1720 feet) high Lituya Bay tsunami of 1958 is sometimes referred as such (despite the wave not reaching that high). In many movies (and some documentaries), there are massive tsunami depicted. Some of these movies depict tsunami taller than skyscrapers (such as in Deep Impact and Haeundae). There is also evidence of massive tsunami occurring in different places around the world in the past.

We have seen the reality of devastating tsunami in and around the Indian Ocean in 2004 and Japan in 2011 for example. These, while not being 100's metres high, are still catastrophic.

How a tsunami forms and how it travels is well documented (thus is not the subject of this question), nor is this asking about the inland reach of such a disaster, they are answered in the related questions Is a mega tsunami that will destroy America inevitable?, Is Atlanta too far inland and too far above sea level to be affected by the comet in “Deep Impact”? and Why does every tsunami travel differently?. But rather, the maximum height possible for a tsunami from any cause.

Is there a theoretical upper limit for the maximum height of a tsunami?

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    $\begingroup$ Is it possible to learn why this was downvoted? What needs to be improved or clarified? $\endgroup$ – user889 Jan 18 '15 at 23:50
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    $\begingroup$ I do not see anything wrong with the question. Seems well researched and clear. $\endgroup$ – gansub Jan 19 '15 at 4:01
  • $\begingroup$ Well maybe somebody does not like the origin of the question came from watching movies as opposed to reading a scientific paper. $\endgroup$ – gansub Jan 19 '15 at 5:37
  • $\begingroup$ @gansub but the references to the movies were just examples of how they are depicted. Certainly not the main focus of the question. $\endgroup$ – user889 Jan 19 '15 at 6:18
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    $\begingroup$ I think (though I'm hardly an expert) that the waves generated by a comet/asteroid impact, or even the referenced Lituya Bay event, would not be the same as a tsunami. They're more of a 'big splash' with actual displacement of massive amounts of water, while a tsunami is an energy wave that's barely perceptible in open water, and only grows on reaching the shallows. $\endgroup$ – jamesqf Jan 19 '15 at 7:14
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Your question seems to lump at least three different phenomena together: tsunami waves(seismic sea waves), the effects of landslides near the coast, and the effects of asteroid impact into the ocean. You might have also included rogue waves. Each of these are complex phenomena when you start considering 'realistic' boundary and initial conditions - so you should not expect a highly accurate answer from a simple model.

Seismic sea waves, or waves initiated by land slide, can travel great distances across the ocean. These waves have a long wavelength and therefore may be modeled as shallow water waves. Although the height of classical shallow water wave may be limited (in theory) by the wave steepness (1:7) where the wave 'breaks' and collapses, Computer models of tsunami are likely to be much more accurate.

If you are primarily interested in what happens near a coastline or in a bay, then the most accurate solution will likely be a computer model that also include realistic boundary conditions. See these computer models of a dam break and waves in an irregular water body.

The possible initial conditions for an asteroid impact could be so large that planetary material is ejected into orbit. The Martian meteorites found on Earth are believed to have originated from a impact on Mars. In a large impact, the height of the rim wall might not be an accurate estimate of the maximum altitude material was actually thrown.

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The height will be limited by the maximum height of the rim wall. For a Chicxulub like scenario the rim wall will be at least a km high. The initial impact will off course cause some water to evaporate, some will be ejected many kilometers into the atmosphere (e.g., during the 'splash') but for the sake of this question I am discarding transient deformation during the first few seconds/minutes and assuming that the Tsunami only results from permanent deformation as in after earthquakes.

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the water would reach a rim, from there it is inevitable to curve, therefore the max would be 3 kilometres due to the mass for it to be not a sheet of water, if it were to be a metre thick the water could reach 9km, if a chixclub event would occur in the pacific, even worse, a larger asteroid. maybe even reaching 10 km as it would reach the atmosphere or evaporate.

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    $\begingroup$ This answer would be greatly improved if it contained a reference to support the claims made. $\endgroup$ – Fred Oct 26 '18 at 1:47

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