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So I have a plot in a story I'm writing where a mage turns a large landmass in the middle of a continent - think something like India - suddenly being consumed by a spell and turned into a dense sphere or disc a couple kilometers across. This would be something that'd consume everything in a 1000km radius sideways and maybe 10 km upwards and downwards ( an actual 1000km sphere would definitely be nothing short of a complete cataclysmic event ), give or take, in a matter of seconds and turn it all into said dense sphere/disc.

  • ~45% is atmosphere
  • ~40% is soil and crust
  • ~5% is fauna and flora ( probably even less? )
  • ~10% water ( probably more? rivers and some small part of an ocean )

Assuming this doesn't create a catastrophic vaccuum - which I'm sure would be the actual result - and instead takes a few days for the environment to normalize, how would this actually happen?

I'm assuming, for a roughly Earth-sized planet, that'd be a significant loss of atmosphere, the ocean's water would rush in and lower the world's water level ( but I don't know by how much? ), there'd be some significant volcanic activity and, of course, the resulting sphere/disc with all that matter would crash down and probably strike the crust at a rather high velocity...Could the planet survive?

This would be something like 130km³ of land and 130km³ of air being "displaced".

Would the planet - assuming it's Earth-like - survive this event?

How much would losing 130km³ of atmosphere affect said planet?

Assuming the ellipsoid is at roughly sea level, something like 130km³ of water would rush in - what would be the effects of such an event on the ocean as a whole?

Would there be some sort of volcanic activity from such an area losing such a part of the crust?

Would the resulting sphere/disc/ellipsoid - which would be 1/500th of the size of the original - be so heavy and dense it'd result in a significant event by itself, from falling some 2km?

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    $\begingroup$ «how would this actually happen?» that has no answer that we can give. $\endgroup$ – JDługosz Jan 18 '17 at 22:37
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    $\begingroup$ I'm completely lost as to what the question actually is, or what is happening. $\endgroup$ – Matt Bowyer Jan 18 '17 at 22:57
  • $\begingroup$ Will be clearer. $\endgroup$ – Arfons Jan 18 '17 at 23:04
  • $\begingroup$ 45% is atmosphere... is this describing what is being replaced or what it is being replaced with? $\endgroup$ – Zxyrra Jan 18 '17 at 23:22
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    $\begingroup$ While instantly loosing 130km^3 of air would be a BIG problem for anyone or anything in the immediate vicinity (shockwaves and all that), in the long term, not that big of a problem really, the Earth already loses something like a 1/4 million tonnes of air a year to space and that's already around 160km^3 so... but yeah, the sphere crashing down would be bad, real bad (probably not to different to this) $\endgroup$ – Samwise Jan 19 '17 at 2:56
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The earth disc/sphere would probably explode when it hits the ground, showering earth everywhere. This and the water rushing into the whole would prevent volcanic activity. However, losing 130 km3 of air would drastically reduce the atmosphere and kill a lot of plants and animals. Some mages could try to block the earth disc from crashing down or create a forcefield around a smaller country to protect it and keep the air from rushing out, but they'd basically be a castle under siege with dwindling food and water supplies. So eventually most life would die(yay!).

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  • $\begingroup$ I don't know. It doesn't seem like removing that much really wouls affect the Earth much. Maybe the surrounding area, but not the whole Earth. Though, if the sphere is compact enough, and is forced down quickly enough, that'd be a lot of force in a really small area, creating a lot of pressure, and potentially causing some major problems. But that would require a lot of speed for the sphere. $\endgroup$ – Iter Jan 19 '17 at 5:08
  • $\begingroup$ Yeah, you're right. $\endgroup$ – KingraHoundoomJazz Jan 19 '17 at 5:08

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