Asclepius hits Antartica

Given that Gilchrist guesses the crater (if it were to hit on land) would be at the very most 10 km in diameter and no more than 600 meters deep, the specified impact site is about the most innocuous one I can imagine!

It would be too bad for the South Pole base of course; possibly the air blast and subsequent seismic and glacial aftershocks would be bad news for the other bases around the periphery of the continent.

But first of all there would be no tsunami, or at least no more than seismic events have been known to cause.

With the impact energy vaporizing ice rather than rock I guess the crater might be significantly larger, but not dramatically so, and even at a kilometer depth I am not sure that would even expose any bedrock. (Some Antarctic mountain ranges run largely under the ice and if the impact happens to be in their area rather than on the thick lens of ice, more rock than I'm imagining would be exposed).

The shock would set the whole Antarctic ice mass a-quiver; this might be bad if it causes substantial shedding of fringe ice into the ocean. But the empty crater at the epicenter of the impact and blast sends a kind of slow "countershock" as it were; ice that was formerly in pressure equilibrium can now surge into the crater; this would tend to bias the ice toward shifting that way overall rather than surging out into the sea.

The biggest problem is the huge amount of water suddenly vaporized. But again, of all the places on Earth for that to happen, I think it's most trapped and localized at a pole. The spreading disk of vapor would have to stretch a long way indeed before its fringe reached the ocean, and I think most of it would precipitate back onto the Antarctic ice cap rather than into the ocean. But even if all of it made it all the way to the ocean before raining back down, the volume of a divot maybe 1 km deep at the center and not much more than 10 km across is very little compared to the ocean, so again I would not anticipate flooding on any of the other continents.

As for major changes in weather, I guess the impact would have some temporary perturbing effect, mainly expanding and somewhat destabilizing the outer fringes of the Antarctic weather zone normally delimited by the Circumpolar Current. But not long after the vaporized moisture has mostly rained or snowed back down to the surface--most likely right back onto the ice sheet in fact--I'd think it would stabilize again in the familiar pattern.

In fact come to think of it this impact might be so harmless that it actually makes the question of human preparedness to deal with potential major impacts even more remote; too many people would shrug off the risk with the false confidence of knowing that a fair-sized rock did hit and nothing much happened. True, but only because it hit the safest bullseye on the planet!

If it were to hit in the middle of Greenland instead people would be more disturbed; possibly the surging outward caused by the initial shock on the ice might lead to some serious splashes; meanwhile the effect of the impact on the northern polar circulation system would disrupt weather right where some of the most influential people on the planet live, while the immediate shockwave might actually lead to fatalities among people flying along the polar air routes.
 
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