Obviously the short answer is 'everyone living 1001+ feet above sea level', but I'm looking for something a bit more nuanced.

Imagine a rolling wave of death - a 'turning off' of the brain, no other trauma involved - originating from France, moving at about the speed of sound. It affects only humans, and once the wave has made its way across the entire world it stops (no ripples, 'aftershocks' or repetitions). The wave is visible only as a slight disturbance in the air as it moves.

Who would be left to pick up the pieces? Which countries/communities/groups would be high enough above sea level, or would be able to get high enough before the wave hit them? Which of these groups would probably die off shortly after through lack of trade/resources/contact, and which might flourish?

But in essence, and most importantly, who would be left?


closed as too broad by Aify, Hohmannfan, Thucydides, Frostfyre, John Dallman Aug 9 '16 at 12:46

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ Related: worldbuilding.stackexchange.com/questions/34626/… $\endgroup$ – user16107 Aug 9 '16 at 10:13
  • $\begingroup$ This could be answered by looking at an elevation map. Regardless, there are several questions here, some of which would require an answer to be unacceptably long (or a bare list). Trying to describe the immediate and long-term consequences of hundreds or thousands of places around the world is far too much for one post. $\endgroup$ – Frostfyre Aug 9 '16 at 12:20

The answer to this is hard... The main reason is no one has collated the data really, but from this paper I can give you a rough estimate of 150 to 300 million at base...

But then there is a second problem with your question. We have worldwide 24/7 new coverage and people would likely pick up on what's going on. Europe would be decimated, but the Americas, Asia, Africa, and Australia all have at least 4 hours before they were hit and they have a high chance of figuring out getting a theory out there and people live near area that are higher all over that are fairly close by so there is a strong chance that the rest of the world survives with 5 to 6 billion people... It just depends on the individuals willingness to listen, believe, act, and how quickly people figure it out and when it happens. If it happens in the early afternoon in France it would be a lot more devistating than if it happened in the late afternoon or evening because people in the other countries for the US but vice verca for Asia.

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    $\begingroup$ Well, airtravel tickets will sell at a premium (if Delta can handle it). $\endgroup$ – Ghanima Aug 9 '16 at 9:05
  • $\begingroup$ How can it be reported on coverage if one would be dead before they can report it? $\endgroup$ – OldBunny2800 Aug 10 '16 at 14:21
  • $\begingroup$ I doubt people in Europe would work out what had happened fast enough to warn Asia/Africa/America/Australia, the event is too specific and unusual. $\endgroup$ – Jon Story Aug 10 '16 at 14:27
  • $\begingroup$ But if they did, I'm driving. I don't have to get far and I know to avoid the freeway. $\endgroup$ – Joshua Oct 15 '16 at 19:04

A rolling wave of death that travels over all media, land and water is fairly difficult to conceive, especially if it does not propagate vertically as well as horizontally. If it travels at the speed of sound, would sound proof/ airtight, rooms/bunkers/vehicles be unaffected or at least weaken the effects? Short term coma or just getting knocked out, instead of dead?

At the speed of sound at sea level, it'll take about 16 hours to cover the globe. Assuming that death is instantaneous, there will be nobody left to raise the alarm, i.e., by the time you notice what's going on, you're already dead. The only warning people will get is that telecommunications become unresponsive, since there's nobody on the other end.

The survivors will be the inhabitants of: https://en.wikipedia.org/wiki/List_of_buildings_with_100_floors_or_more; and people currently on aircraft above 1000ft and people living in the Alps, the Andes (central S. America, in general), some of central America, the Himalayan foothills, some parts of China, and in the Ural mountains, off the top of my head.

Most of these people will die within the week, as corpses begin to fester and breed disease. If the wave affects animals as well, then most mammals, at least, probably also fish and reptiles, will die as well, adding to the mess. The knock on effects on the environment will kill most of them anyway, as the wind and rain washes the rotten bodies downstream.

People dependent on modern infrastructure will be severely affected, as there will be nobody left to maintain them; those communities that still aren't so dependent will carry business on as usual, for the moment.

By rule of thumb, 1 kg of biomass gives 1 mol of methane. Let's say 6 billion dead, 70 kg on average, gives 10^13 litres of methane at room temperature/1atm. Global warming effects aside, methane is slightly heavier than air, so will not easily dispersed in enclosed spaces, like cities, which is where most bodies will be. Cities, therefore, will be a fire hazard until sparks from unattended fires, electrical equipment etc., burn them down. Hopefully, this will deal with most of the the water pollution and disease issues.
Nuclear power plants, chemical factories,etc., are the next source of concern, along with nuclear and chemical arsenals. Depending on how the safeties are set up, unattended, these systems will force an automatic shut down. Otherwise, with no load to supply, the plants will explode; the nuclear arsenals will assume a decapitating strike and launch at preassigned targets, at best irradiate everything within their blast radius, at worst rupture the Earth's core.

In any case, the sensible thing for the isolated survivors to do would be to stay where they are, for the next few decades or so; afterwards, it depends on the survivors' technical expertise and what's left.

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    $\begingroup$ Much more territory than you realize is above 1000 feet...see the map I linked to. $\endgroup$ – user16107 Aug 9 '16 at 10:43
  • $\begingroup$ wouldn't be surprised. As I said, off the top of my head $\endgroup$ – nzaman Aug 9 '16 at 13:40
  • $\begingroup$ Warning would spread--there are tons of webcams--people would see it. There would also be planes that landed behind the wave and saw the results. $\endgroup$ – Loren Pechtel Aug 9 '16 at 18:35
  • $\begingroup$ 32 hours is wrong. If you start at a point and go one direction it'd take 32 hours, but it's going all directions at once which would mean 16 hours to cover the whole globe. France is about 5 or 6 hours from the East coast of the US and Hong Kong. If you want to see how far it'd go in x time it's fairly easy to see it with most art programs with the circle tool... $\endgroup$ – Durakken Aug 10 '16 at 3:36
  • $\begingroup$ true. Corrected above $\endgroup$ – nzaman Aug 10 '16 at 5:14

This tool lets you set a water height and see what areas would flood. It's a good gauge of what areas of the world would survive.

A surprisingly large percentage of the world's land is over 1000 feet elevation. However, nearly all of the major population centers are coastal, so most of the world population would die (Note how well the red areas of this population density map correlate with the areas that are flooded in the above map).

Most of the major areas of economic activity would be completely obliterated. Most world governments would be wiped out, and chaos would ensue. Some key industries, like fishing and shipping, would be completely gone, with major effects on the surviving population.


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