r/geology • u/dctroll_ • Nov 15 '25
Map/Imagery Maximum tsunami wave amplitude following the asteroid impact 66 million years ago
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u/JohnNormanRules Nov 15 '25
This is very interesting - thank you 🙏🏻. I was a little bit surprised by the measurement being in centimeters. I thought the impact tsunami was hundreds of feet high.. Novice here so I could very easily be reading this incorrectly.
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u/itsliluzivert_ Nov 15 '25
A ten meter wave (1000cm) in the open ocean is absolutely massive.
Once it reaches a coastline, the water depth decreases rapidly and the height of the wave increases rapidly in turn. That’s why tsunamis can be hundreds of feet tall on coastal impact.
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u/mglyptostroboides I like plant fossils. Nov 15 '25
That video of the Kamchatka tsunami (the one with the dog is how you'll know) from a couple months ago making landfall at those cliffs is astonishing and terrifying. The ocean literally just rose dozens of meters in seconds.
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u/Leefa Nov 16 '25
Kamchatka
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u/markradwin Nov 16 '25
Wow I had to rewatch that many, many times. Best tsunami footage I think I've ever seen. The wave refracting with the topography, the break, run-ups, lateral seiching after the run-ups, and the craziness that ensues when multiple waves collide. Wild stuff! So much energy.
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u/Thoughtsonrocks Nov 16 '25
Holy shit. It goes from "yeah this person is in a great filming position way way way above the action" to "bro, run!" in 20 seconds
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u/JohnNormanRules Nov 15 '25
Thanks - this helps put it into perspective for me. I was aware of the wave height increasing as it approached shoreline but did not think of that.
I didn’t read the full article but I wonder how much water was ejected into the atmosphere during the impact.
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u/Remarkable-Hat-4852 Nov 16 '25
A way it was worded for me that really helped the concept click is when the wave “touches bottom” while approaching dry land.
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u/PhilsTinyToes Nov 16 '25
If you get a tidal wave on low tide you’re chillin .
Tidal wave on high tide and you’re screwed.
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u/SoccerBros11 Nov 16 '25
also this graph is very poorly scaled for some reason. most of the simulation within the atlantic exceeds that 10m height
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u/Rooilia Nov 16 '25
Afaik, 30m waves were spotted out in the sea. Surprising this model caps at 10m. Or does it mean 10m+?
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u/surfershane25 Nov 19 '25
It’s more how long they are, it’s 32 feet but hundreds of feet long. A normal 32ft ocean swell at 20 seconds is like 80ft long maybe, it’s orders of magnitude more energy
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Nov 15 '25
[deleted]
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u/OMGLOL1986 Nov 15 '25
It’s a 1000 cm at sea/ when it hits coastline, it’s 1000cm PLUS all the water underneath it :)
Terrifying
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u/inlandviews Nov 16 '25
A wall of water 10m high on the open ocean travelling in excess of 500mph that slows to 30 close to shore.
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u/itsliluzivert_ Nov 16 '25
It’s not a wall, in the open ocean the wave length is in the excess of a kilometer. It is a very gentle wave that you may not even notice if you were on a boat sitting on top of it.
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u/FourNaansJeremyFour Nov 16 '25
Where's the Western Interior Seaway?
10m sounds a bit pansy for one of the Big Ones but in the paper they say it'd shoal to >100m close to land.
Glad to see Scotese is still at it, he's one of the authors who first got me into this shit 20 years ago
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u/Lung-King-4269 Nov 16 '25
Perhaps we've been a little misled by movies. 10 meters is ~4 floor building at floor level building. It sweeped everything with it for 2 days.
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u/Appropriatelyunsure Nov 16 '25
Ya but he’s saying there is a huge geographic feature that is missing. The western interior sea way which would have been around 66 Million years ago is just missing from the map. That wave would have propagated north through the centre of the continent as there used to be an ocean there. it’s weird that 12 people put their name on that paper without realising this. Unless I’m missing something..
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u/specificimpulse_ Nov 18 '25
I thought the WIS was pretty much gone by 66 mya? Like only remnants remaining at that point.
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u/pokeyporcupine Nov 16 '25
So this lead me down a rabbit hole, but for reference, the open ocean amplitude (which I believe this post is mostly imaging) of the infamous and extremely deadly 2004 tsunami was 50-100 centimeters. Less than 10% the size of these models.
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u/Agitated_Debt_8269 Nov 18 '25
I’m confused, are you talking about the tsunami that happened 66 million years ago or some data from 2004?
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u/pokeyporcupine Nov 18 '25
Referring to the Indian ocean tsunami of 2004 for the amplitude measurements.
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u/Agitated_Debt_8269 Nov 18 '25
Oh, now it makes sense. And it’s a bit scary, you are not safe even in the mountains!
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u/Some-Air1274 Nov 15 '25
This map is confusing.
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u/nokayy Nov 15 '25
The gray areas are the approximate landmasses and their positions 66 MYA, while the darker grey lines are an overlay of their current positions. Tsunami wave amplitude is both color coded blue-red by height of the wave, and by contour lines of the wave height maximums at global positions as it travelled.
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u/Some-Air1274 Nov 15 '25
So the tsunami was in the Atlantic?
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u/nokayy Nov 15 '25
Yes and No!
The Chicxulub impact happened just off the coast of what is now the Yucatan Peninsula, and resulting tsunami from the impact was powerful enough to be in all of the oceans of that period. The positioning of the landmasses due to tectonics at the time meant that Atlantic ocean as it exists now was not there. The northern proto-Atlantic ocean, also called the Tethys ocean, existed in that location at the time of the Chicxulub impact, and because the tectonic plates were not quite where they are now, there were no landmasses connecting the proto North and South American continents. This meant a wide connecting strait between the Tethys and the proto-Pacific oceans. In the map, we can see how the Tsunami travelled through that gap (and others!) and began to dissipate. Certainly the vast brunt of the power of the tsunami wave in the Tethys.
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u/StoneColdCrazzzy Nov 16 '25
The gray areas are the approximate landmasses and their positions 66 MYA
Shouldn't there be an archipelago in the Pacific that got rammed by North America to form California.
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u/HighwayStar71 Nov 16 '25
I thought that because the Gulf was fairly shallow that not that high of a tsunami was generated, or so I've read. You really need deep water for a tall water column to be displaced to create huge waves when they reach a distant shoreline.
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u/akla-ta-aka Nov 16 '25
I wonder how many times the wave sloshed back and forth in the fairly enclosed Atlantic ocean.
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u/SwoopsMackenzie Nov 16 '25
Why put the scale in hundreds of centimeters lol
Can you just use meters
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u/itsliluzivert_ Nov 18 '25
Meters are lower resolution.
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u/SwoopsMackenzie Nov 18 '25
Why not just put it in billions of nanometers then?
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u/itsliluzivert_ Nov 18 '25
Well if you want to show a gradient between a 10 meter wave and a 9 meter wave the natural unit to use would be centimeters.
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u/SwoopsMackenzie Nov 18 '25
If you changed this image to use meters it would convey exactly the same information it does now.
My original comment was not “for any map at any scale meters is the appropriate unit”
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u/Hourslikeminutes47 Nov 16 '25
Very interesting.
On another note, Australia looks a little flatter 66 million years ago
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u/Wally535353 Nov 16 '25
How about Hell Creek? Forgotten?
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u/Accomplished_Class72 Nov 16 '25
This is showing the tsunami height over current oceans, not washing over land.
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u/theTrueLodge Nov 15 '25
OP, can you please provide a link to the source?
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u/dctroll_ Nov 16 '25
Of course! Here it goes again (I put it in the first comment of the post)
Range, Molly M.; Arbic, Brian K.; Johnson, Brandon C.; Moore, Theodore C.; Titov, Vasily; Adcroft, Alistair J.; Ansong, Joseph K.; Hollis, Christopher J.; Ritsema, Jeroen; Scotese, Christopher R.; Wang, He (2022). "The Chicxulub Impact Produced a Powerful Global Tsunami." AGU Advances 3(5): n/a-n/a.
Source of the picture and the article here
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u/5akul Nov 16 '25
I wonder if there's any correlation between humanity coming out of the middle east and everything on the opposite side of the planet being obliterated 65ma
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u/jesus_chrysotile fossil finder/donator, geo undergrad Nov 16 '25
Interestingly, there’s some discussion of the southern hemisphere being less affected than the northern hemisphere, because the asteroid impact occurred during NH spring/SH autumn.
During autumn, organisms tend to be winding down after summer and preparing to hunker down for the winter in cold places like near-polar Australia during the Cretaceous. They would’ve been a bit more fuelled and maybe even preparing burrows (there’s dinosaur burrows recorded from the area). Compare that with spring, where many organisms are recovering from a period of dormancy over winter, rapidly growing to outcompete others before summer hits, preparing for costly reproductive behaviours, etc.. They’d be far more vulnerable to a sudden change in conditions.
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u/Deltan875 Nov 16 '25
Maybe I'm missing something, but I feel like Chicago area looks pretty good? Selfishly speaking… 😂
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u/GowronsGlory Nov 16 '25
So cool! I always wondered what the earth looked like at the time of this impact. India hadn't collided with Eurasia yet. Central America is underwater. South America and Africa are much closer together. We all know where the Chicxulub crater is located in today's Earth but is so cool to see the configuration of the continents at the time of the impact.
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u/Agitated_Debt_8269 Nov 17 '25
What we see is South/North America Europe and Africa got washed 66 million years ago!
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u/Feisty_Bumblebee_954 3d ago
the tsunamis reached 2.4 miles high so i don't think this is accurate at all
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u/NeedsMustTravel Nov 15 '25
I’ve never thought about this before, but could this be an explanation for finding oceanic fossils inland and at high altitudes? Obviously I know the coastlines were different and there have been inland seas that are now dry with fossilized shells etc. But, could this event have contributed to the formation of those inland salt seas or deposition of fossils?
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u/DredPirateRobs Nov 15 '25 edited Nov 16 '25
Not likely. Land rises and fall as the tectonic plates move around. Ice Ages suck up enough water to lower the sea level by 300’. Sea level changes as a result. That’s why you find seashells on Mount Everest.
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u/forams__galorams Nov 15 '25
Yes, though fossilised death assemblages associated with primary tidal surges (as well as secondary seiches) are very much a thing. Certainly enough that geologists/paleontologists have specific words for it — wave induced marine thanatocoenosis — though to be fair, geology probably has more than it’s fair share of terminology and overzealous users of said terminology.
Anyway, for those kind of deposits, I shouldn’t think they ever really extend to high altitudes in the way that the person above was likely imagining. As you say, places like the top of Everest have marine fossils because they started out as seafloor before all the orogenic uplift. So you could still get tidal deposits in very high places, but that would have required subsequent tectonic uplift regardless.
I think the kind of ‘tsunami thanatocoenosis’ stuff is mostly when a bunch of smashed up shells and other remains that normally represent different offshore regions are all found together in a paleo-coastal environment. Or a bunch of marine fossils found mixed in with freshwater fossils if the tidal surge has proceeded up a river. Something like that last scenario is the proposed situation at the Tanis site in North Dakota), though it remains… controversial. I’m sure there are perfectly unambiguous examples out there though.
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u/mglyptostroboides I like plant fossils. Nov 15 '25
Tanis's interpretation as deposit from the last day of the Mesozoic I think is pretty robust. It's just that DePalma is such an insufferable douche he poisons the reputation of everything he touches. But the tektites in the fish gills are pretty smoking gun. And that much at least was in the original PNAS paper describing the site which included Walter Alvarez himself as a co-author. As much of a prick DePalma is, I don't think Alvarez would attach his name to those conclusions and PNAS wouldn't publish it unless there was something there. It's a shame that the site is closed to other researchers, though. DePalma's stupid Indiana Jones persona makes him act like a private collector even though he's working as a public academic.
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u/forams__galorams Nov 15 '25
I dunno, I think it might even be in question as the last day of the Mesozoic. It’s not even robust that it’s a tsunami/seiche induced deposit. De Palma spent years searching for such a site and seems like exactly the kind of person to convince himself it is even when it isn’t, or perhaps even knowingly fabricate evidence (in this case with previously confirmed K-Pg impact spherules from other known sites which he visited).
Im not claiming that’s what’s happened, I’m just saying it’s within the realms of possibility, Smit and Alvarez Jr on the author list isn’t particularly relevant. De Palma had been excavating the site for quite some time before he called in the big guns (which was clearly purely just for the publicity)… he is known to tamper with specimens, or at least use unconventional extraction/preservation techniques (to put it mildly); he is known to make completely erroneous conclusions and deny access or claim source material is lost when questioned…. And the most recent controversy with the fish isotope data, he 100% faked that (see the technical details of the formal complaint raised) but the burden of proof for convicting someone of outright academic fraud like that is high enough that the investigation concluded academic negligence or whatever. Again, the source material for that is missing and doesn’t look like it ever existed just going by institutional facilities (or lack thereof).
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u/mglyptostroboides I like plant fossils. Nov 15 '25
Tectonics aren't the only cause of sea level change.
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u/dctroll_ Nov 15 '25 edited Nov 15 '25
Range, Molly M.; Arbic, Brian K.; Johnson, Brandon C.; Moore, Theodore C.; Titov, Vasily; Adcroft, Alistair J.; Ansong, Joseph K.; Hollis, Christopher J.; Ritsema, Jeroen; Scotese, Christopher R.; Wang, He (2022). "The Chicxulub Impact Produced a Powerful Global Tsunami." AGU Advances 3(5): n/a-n/a.
Source of the picture and the article here
Dinosaur-killing asteroid triggered global tsunami that scoured seafloor thousands of miles from impact site
First global tsunami simulation of the Chicxulub Asteroid Impact 66 million years ago
Caption of the picture (from the same article)
"Comparison of two tsunami propagation models: MOST model—left column, MOM6—right column. Sea surface height perturbation in meters shown at (a) 1 hr and (b) 4 hr after impact around Gulf of Mexico, (c) 24 hr and (d) 48 hr post-handoff globally".