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Comment by geuis | Hacker News Reader

Just to put the numbers in slightly easier to imagine numbers: imagine ocean waves about 13000 feet or 4 kilometers high.

No, I can't really imagine it either.

In San Francisco, the tallest building is the Salesforce Tower at 1070ft. The biggest wave would be about 13 times taller than that.

I totally have trouble visualizing it, other than just looking up and up and up.

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When I went to the Grand Canyon I was surprised at how little my brain could comprehend the depth. There are so many false bottoms, when you're up on the rim, you look down and you see something you think is the bottom, but then you realize there's still a canyon below that, then you look down into that canyon and find the bottom, and then you realize there's still a canyon below that. It's like your brain absolutely cannot process being 2 kilometers above the bottom. That's what I thought of when I read your post.

(I had a similar feeling when I was in the High Atlas mountain range in Morocco and tried to look up to the top)

The article reads to me like the 4.5 km wave was an initial "splash" which dissipated but the actual tsunami was "only" 1.5 km high. Imagine throwing a good sized rock into a pond: Big initial splash, then smaller waves radiate out. Of course, to observe the proper effect, you would need to throw your rock at 20 km/s into shallow water.

> a curtain of ejected material pushed a wall of water outward from the impact site, briefly forming a 4.5 kilometers high (2.8 miles) wave that subsided as the ejecta fell back to Earth. Ten minutes after the projectile hit the Yucatan, and 220 kilometers (137 miles) from the point of impact, a 1.5 kilometers high (0.93 miles) tsunami wave—ring-shaped and outward-propagating—began sweeping across the ocean in all directions

When I went skydiving, they took me up to 12.5k feet. Good weather was necessary, and they offered to only go to 9k feet if I was a little "scared". Not sure why jumping out of a plane at 9k feet is any more reassuring... A wave that tall is insane.

Mt. Fuji stands at 3.8km (12,467ft). They say the wave reached 4.5km, so maybe Mt. Fuji with the Burj Khalifa (~800m) on top? Still very difficult to picture as a wall of water.

Those aren’t mountains.

The best hope would be that the mountains and ground whittle it down and that it drains quickly. May explain why rodents survived, in that dry to moderately dry ground doesn't soak up water quickly, so if it drained away before the burrows were soaked/drowned, there is a chance at survival.

Likely such a wave would scour the coastline many, many miles inland and the land would essentially have to be re-settled all over again by all of the life forms that thrived there before. There is very little chance that a burrow would not be flooded, but many rodents are good swimmers and there will be lots of stuff floating about.

There was a lot more to worry about than the wave. Anything within about 1500 km of the impact site was instantly vaporised. Then afterwards the whole atmosphere was oven-hot for several minutes. Then there was very little sunlight for decades. https://www.youtube.com/watch?v=dFCbJmgeHmA

Is it the consensus that the entire planet's atmosphere was oven hot from re-entering ejecta, or is that just one particular model? I've heard various claims about the dinosaur extinction event, from the nuclear winter type scenario to all the non-avian ones dying with in an hour to a day after the impact. I've also heard different nuclear holocaust scenarios from the nuclear winter lasting as long as 10-15 years, to there being no nuclear winter, all depending on whether the burning material reaches the stratosphere in large amounts.

Safe to say we don't have real world examples to test at planetary scale, so I'm a little skeptical as to how accurate any of these models are. We just know the result was a planetary-scale extinction event for at least 60% of life, although there is also the possibility of multiple impacts, and previous volcanic activity aiding the extinction.

Consider that the peak of Olympus Mons[1] on Mars is 26 km (16 mi) above the plain.

It's unlikely that it's the tallest mountain in the universe, though, and a true pity that if the current understanding of physics is correct, and we can not travel faster than the speed of light, no human will ever experience those massive, distant mountains outside our solar system except in images or virtual reality.

[1] - https://en.m.wikipedia.org/wiki/Olympus_Mons

Hm, I have much more difficulty imagining how far inside the shoreline that would go - so if I take a port city, is it wiped off completely? Does it matter if it goes uphill for 10km? 100km?

I was wondering the same. the simulation doesn't appear to account for the landmasses, treating them as impenetrable barriers. where is the flooding simulation? are we to assume the shores were 5km high vertical rock?

One of the science show (Nova ? could not find it quickly) did an extinction event analysis on a point far upstream a river and tied it to the Chicxulub event. The local flora and fauna were killed by water flow high up river and hot ash rain.

Is it closer to Interstellar's wave planet?

more like Deep Impact's wave I'd imagine. Though the wavefront there probably looks too sharp?

Deep Impact's wave was barely taller than the WTC towers.

4.5km would dwarf that.

And this would be in the context of the atmosphere vaporising followed by a massive shockwave and a 10km mountain of the earths crust rising up towards the sky at the point of impact. https://www.youtube.com/watch?v=dFCbJmgeHmA

Don’t imagine it as a wave like one people surf on. Imagine it as a tide.

Either way I'm imagining "The ocean is suddenly 4km higher than it normally is".

I can visualize: the highest peak around me is 3200 km

m not km I presume

That’s the moon. ;-)

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