Designing an apocalypse to order

[Kale]

Originally Posted by Michael Thayne

Where I'm seeing discrepancies between AtE and what I'm planning is I'm planning to have Earth largely recovered after 200 years, which probably translates to six or seven generations. AtE suggests requiring Anthropology rolls for all but the most basic facts about the old world after four to six generations, and for all facts about the old world after seven to ten generations. On the other hand, I'm assuming that if nothing else contact with space colonies prevents that level of knowledge loss. AtE furthermore assumes that the genre shifts to futuristic sci-fi after more than ten generations, and I specifically want a shorter timeline so the space colonies don't have too long to grow--I want Earth to be able to bounce back as a hegemonic power by the setting's "present day".

Ah, I see. The colonies would probably also have excellent archives etc. which would prevent quite a bit of the knowledge loss from a typical AtE scenario. I understand now why you say it doesn't fit the typical AtE mold. This is more of a disaster recovery story than an AtE story. On that note, consider looking at historical examples of disaster response in the real world for plot ideas. While we haven't had many meteor strikes, the general devastation from a big fire/storm/flood and how people and governments historically dealt with it should give you some inspiration.

[(E)]

Would an incident that left low orbit crowded with debris help to isolate earth. Possibly combine this with an EMP type effect that causes wide spread infrastructure loss.

[Anthony]

On the original point, if you're asserting a war, it doesn't actually that much matter the weapons used during the war -- any form of high intensity warfare or extended moderate intensity warfare using high or ultra tech weapons will be a disaster for the area in which it occurs.

[Varyon]

Originally Posted by Michael Thayne

Hmmm. I wonder how big of a comet you'd need to basically render both New York and DC only dubiously worth resettling at the same time? Probably bigger than the Chicxulub impactor if we're talking about a crater from a land impact, but a water impact in the Atlantic could create huge tidal waves. But I don't know, like, how big of a tidal wave it would take to level every skyscraper in New York City.

Multiple impactors (probably due to a single impactor breaking apart upon contact with the atmosphere) can allow you to destroy what you want without requiring too large of a single hit. As for those two specifically, a direct impact on DC would probably result in the crater returning to swamp land in relatively short order, so you'd probably only resettle if you're desperate for land or want it back for nostalgic/political purposes. New York City could probably get knocked underwater, with New New York (or whatever you opt to name it) possibly built in the outskirts (although probably north or south rather than inland if it's going to be a (sea) port; the crater area is probably too shallow and hazardous).

[dcarson]

New York is the mouth of a major river. There will be a some sort of city there. Look at New Orleans, a small bit (the french Quarter) is above sea level but since it is the only high ground for at least another day upriver they built a city there.

[Michael Thayne]

Originally Posted by Varyon

Multiple impactors (probably due to a single impactor breaking apart upon contact with the atmosphere) can allow you to destroy what you want without requiring too large of a single hit. As for those two specifically, a direct impact on DC would probably result in the crater returning to swamp land in relatively short order, so you'd probably only resettle if you're desperate for land or want it back for nostalgic/political purposes. New York City could probably get knocked underwater, with New New York (or whatever you opt to name it) possibly built in the outskirts (although probably north or south rather than inland if it's going to be a (sea) port; the crater area is probably too shallow and hazardous).

Now I'm thinking more about New York. Anything that makes a crater the size of New York City is probably an extinction-level event. So let's say instead of something like the Chicxulub impactor (believed to be many miles across), a half-kilometer comet hits Queens. What happens to Manhattan, in that scenario? The broader region? I've seen projections that a "supervolcatio", which AFAICT would involve the same order of magnitude of energy, would likely cover a large area in several feet of ash. But the material kicked up by a comet might be smaller in volume relative to the amount of energy involved. Or it might be distributed differently. Anyone know much about impact craters?

[Anthony]

Chixulub crater is 150 km across, way bigger than NYC. Crater diameter is way larger than meteor diameter.

[Michael Thayne]

Originally Posted by Anthony

Chixulub crater is 150 km across, way bigger than NYC. Crater diameter is way larger than meteor diameter.

The Chicxulub impactor wiped out almost all large tetrapods, and is thought to have been at least 11 kilometers across, which is why I suggested a half-kilometer object.

[Anthony]

Oh, I was missing the need to have both NYC and DC from a single event. However, not sure why an extinction-level event is inappropriate; if you want to greatly reduce the relevance of Earth as a whole you need planetary scale destruction. Humans are pretty adaptable, if you're posing interstellar travel before the event that's enough tech that humans on Earth would survive.

[Bengt]

A Chixulub sized meteor wouldn't even be an extinction event for 2020 humans would it? I mean lots of species survived the original Chixulub and we are ruthless bastards with technology to mitigated the effects.