Crazy earth "destruction" question.

Post by **weemadando** » 2006-10-07 07:05pm

OK - assuming one day that by act of physics defying explosive force a MASSIVE chunk of the earth is removed by some sort of explosion is space, leaving a gaping (unsealed) crater 4000km across and say, 1000km in depth (down to the lower mantle).

This creation of this crater leaves EVERYTHING else intact - atmosphere, anything immediately beside the "disappeared" zone is not effected. The ONLY change caused by the explosion is that a large chunk of the earth disappearing, leaving the lower mantle exposed.

What happens at this point?

Feil · Post by **Feil** » 2006-10-07 08:02pm

We all die horribly in the insuing climate shifts, tectonic insanity, orbital instability, and, last but not least, the giant plume of flaming ejecta that is propelled into the upper atmosphere by the sudden imballance of pressure between the disappeared part and the undisappeared part. That done, Earth regains its spherical shape in reasonably short order, cosmically speaking. Earth's orbit gradually spirals out until it regains stability somewhat further from the sun.

The giant alien warships on thier way to consume all life on Earth establish a research base to figure out who screwed up their snack, resulting in their eventual discovery of a second interstellar civilization. Galactic war ensues. Quadrillions die.

Lost Soal · Post by **Lost Soal** » 2006-10-07 08:05pm

While nothing may have been affected by the explosion, ~12,566,370 km^2 of magma now has nothing to stop it rising up and destroying large quantities of the surrounding area. Not sure how much though.

Molyneux · Post by **Molyneux** » 2006-10-07 08:23pm

MAJOR bad things for life on Earth - wouldn't we get some nasty winds from the atmosphere rushing in to fill the gigantic hole, and incredible lava-geysers from the pressure on the exposed mantle?

Post by **weemadando** » 2006-10-07 08:27pm

Earth being sterilised was a given. The side-effects are awesome.

Lord of the Abyss · Post by **Lord of the Abyss** » 2006-10-08 05:53pm

One such effect; massive winds and loss of pressure for a wide radius as the atmosphere implodes into the sudden vacuum that has replaced all that rock. Then, as the surrounding rock falls in and forces the air out, the previously mentioned "giant plume of flaming ejecta" spews out, including a massive and very hot atmospheric shockwave.

Admiral Valdemar · Post by **Admiral Valdemar** » 2006-10-08 06:18pm

It wouldn't be as bad if the chunk just lifted up slowly and floated off. But having the mass just vanish will, as mentioned, cause a massive bang when that vacuum is sealed by molten rock and atmosphere. The shockwave will fuck over most of the planet, then the thermal effects from that massive body of magma will raise global temperatures a few degrees, likely steam off a load of ocean if this was near a major water mass. There might be a slight gravitational disruption too, though that'd be the least of your worries if you happened to survive the initial incident.

Wyrm · Post by **Wyrm** » 2006-10-08 06:43pm

A thin-shell approximation of the earth's atmosphere puts the total volume of the troposphere (the part we live in) between 8.16e9 km³ to 4.08e9 km³ in volume (it varies between 8 km at the poles to 16 km at the equator). The hole made in the ground can be thought of as an "ice creme cone", that is, a section of the earth separated if we were to cut in a flat plane such that it makes a circular face 2000 km in radius (4000 km in diameter), plus a right conical section using this circular face as a base and extending down until the point is 1000 km from the former surface.

A cleave 2000 km in radius from a sphere 6000 km in radius would have maximum depth of 343 km, and a volume of 2.177e9 km³. The cone that forms the rest of the volume is 2.75e9 km³, for a total of ~4.9e9 km³ of volume. (If anyone wants, I can post the derevation.) This is on the same order as the atmosphere, and just barely greater than the lower limit of the possible range for the troposphere. The crater is large enough to sink 9.6 km of atmosphere.

We probably won't completely suffocate, but it will probably mean that world climate would be royally boned.

Sriad · Post by **Sriad** » 2006-10-09 02:18am

I'm thinking the Earth would all kind of squish back in to fill the crater and we'd all die in titanic tectonic chaos.

Wyrm · Post by **Wyrm** » 2006-10-09 02:30pm

Sriad wrote:I'm thinking the Earth would all kind of squish back in to fill the crater and we'd all die in titanic tectonic chaos.

Yeah, the Earth would do this. I was using a rigid ball approximation, which doesn't really work here. The surface of the earth is held up by pressure from below, so when the weight of the surface is gone, the pressure forces mass to go up inside the crater, while other places go down by the same amount.

The amount the earth shrinks to fill this hole? About 9.6 km, because this is about how much material needs to be scraped off the earth to fill the hole. And yeah, this would cause much tectonically destructive goodness.