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Re: deep water = less ejecta?



----- Original Message ----- From: "Tommy Tyrberg" <tommy.tyrberg@norrkoping.mail.telia.com>

Things would be very different for a hit in really deep oceanic water,
where an appreciable part of the depth of the transient crater would be
in water rather than rock. In such cases even a fairly large bolide
might not even leave a discernable crater on the bottom.

But:
"We discovered that the shallow structure of the crater was determined much more by what the impact site was like before impact than by the trajectory of the impactor," says Gulick.


My reading of this is that they infer deep water from the shallow nature of the crater--meaning (I think) that the water absorbed enough energy to blunt the force on the ocean floor. In any case, if the crater is shallow it follows that less ejecta was blown out (right?); and that there was a greater percentage of water vapor in the mix (by the way, if there was 6.5 times more vapor, how much _less_ rock does that mean?).
If the water/rock ratio was appreciably different this should have a different effect than previously believed. For example, heat energy in water vapor would have a more local effect...at least versus the re-entry of solids globally.