A hole is drilled through the center of Earth from dry land to the bottom of an ocean. What then happens?

Question

The core of the Earth is very hot, sufficient to convert seawater into superheated steam. Does it blow out at both ends, preventing seawater from flowing into the hole, or does it blow out only one way, creating a nonstop geyser on the dry land side, thereby providing a source of geothermal energy? Is this analyzable as a physics problem?

jp78, this problem is about the case where one side is dry land, the other at the bottom of an ocean.

A 19th century steam engine designer would recognize this problem. It's the same principle of how water is boiled into steam and used to drive pistons. Imagine that we have a long sloping cylinder of one diameter, and a piston at both ends. Water is introduced into the lower end of the cylinder, and fire is applied to the middle of it, producing steam which rises, creating an overall pressure inside the cylinder, the weight of the water being neglible. The work of pushing water into the cylinder at the lower piston is only a fraction of the work produced by steam at the higher piston, since steam takes up more volume but at essentially the same pressure. Likewise, water pressure at the entrance of the hole at the bottom of the ocean is matched by steam pressure at the dry land hole, regardless of elevation. A nonstop geyser will be produced until the ocean is dry.

Answer 1

Let's assume both drilling locations are equidistant from the center, for simplicity.

To see what might happen, let's look at the situation if the center of the Earth were not hot, just empty space. Now imagine you do something simple, like drop a ball down one end of this tube. The ball will be pulled toward the center of the Earth, reach the center, and continue onward towards the other side. But the center will still be pulling on the ball. Because of friction, the furthest that ball is ever going to go will be the opening of the other end of the tube, and it almost certainly won't make it that far before turning around. Eventually, we'd expect the ball to stop in the center of the Earth.

Water would act the same way, but with a some complications. Water would not only be pulled towards the center, but pressure from the water above it (I'm assuming the ocean) would factor in as well. Since water is more dense than air, we might expect water to completely fill the tube and begin spilling out onto dry land on the other side of the world. Eventually an equilibrium would be reached, with equal amounts of water (more or less) on either side of the world, assuming it's collecting around the tube opening on the dry side. If it's not, we could expect much of our ocean to drain right through, until a different kind of equilibrium is reached.

Of course, your question adds one more complication. The center of the Earth is quite hot, and it gets very hot long before you even reach the center. Several scenarios are possible here, depending on the density of water versus steam, and how hot the center of the Earth gets. I'm not doing the math, so I'm just presenting some possibilities.

If the ocean above is heavy enough, it might just add enough weight to push the water on through, heat and steam be damned. The center wouldn't be hot enough to vaporize all the water as it passed by, and we'd end up with an equilibrium similar to the one above. You probably wouldn't get steam out of either end, as it would just condense back into water before it ever got back out. Just a big convection cycle.

If the center is hot enough, all the water gets vaporized before getting past the center. At this point it's going to turn around and fight gravity as it travels up through the much denser water. We might get to see some steam travel up and out of the hole on the watery end, but it will most likely condense back into water before reaching the exit. Another big convection current, this time only on one side.

Another possibility lies somewhere in between, where the amount of water getting vaporized is high, but some still makes it through. In that case we'd just have an equilibrium reached where the water level only rises to a point inside the tube somewhere, with never enough pressure behind it.

In any of these cases, it is possible that steam might rise out of the dry end, but I tend to think it would all condense during the miles it would have to travel to the surface. Only in the first case could you potentially see a geyser effect.

Answer 2

To begin with no 'convertion of seawater into superheated
steam' will occur. Because 'water' and 'steam' are the both
the same phase, and distinction beween them is possible
only when they co-exist along phase separation line.
The critical point of water is at P = 225 atm ~ 2.2 km below
sea level.

After the system settles, we will have simple 'non-crystalline'
phase of water, all the way down and then up with temperatures
and pressures T(r), P(r) symmetric with respect to the center
of the earth. The net effect will be the same as taking
U-shaped tube filled with water and heating the bottom of it
using kitchen stove.

There will be probably some convection currents, maybe
even boiling at and near the surface, but nothing spectacular.

*******
Unfortunately I was unable to find the phase diagram of
water at high enough pressures, but as far as I recall,
somewhere in thousands of atm's the temperature of
melting point begins to increase reapidly. So mayby
there will be ice in the center.

Answer 3

well, first of all, the center of the earth is molten, so your hole would collapse in the middle. Let's say you've stuck some kind of tube of really tough material all the way through so the hole stays open. as you go further down underground gravity is actually weaker and weaker (think about it, gravity comes from mass so as you drop down there's more and more mass above you pulling you upwards and therefore reducing the amount you're getting pulled down, in the center there's no gravity at all).

so it's all about the different forces and conditions all the way through the tube. At the bottom of the ocean, there's lots of gravity downwards, there's lots of pressure of the water above, there's not much heat. as you go downwards, gravity is less, heat is more, and the pressure depends on what's happening above you. As you get towards the other side of the planet gravity increases again, there's air pressure...

so yeah it's a physics question, but it's some really complex bit of maths to work out how all the different aspects work together.

let's look at it another way... once you drill the hole things will keep happening until the whole system is in balance. balance would be when there's half the lake on each side of the planet. so maybe there will be water pouring out the other side until half the lake has crossed over. now the question has to be, will it come out as steam or will it have cooled down again to water. that's where you'll have to go to the maths again.

so i guess i don't know the answer but this might help you work it out.

Answer 4

I would personally imagine that the airspace would be displaced with water,and the sea levels would drop! But I could also suppose that this is impossible too,because the center of the earth is 'Magma' or Molten Rock! It could possibly create a 'Geyser Effect' but I really doubt it could at some point,because the airspace would very quickly be filled in by molten magma-if the drill has not already melted? Any Physicists' out there to answer this interesting Question? Thx. theerrander.

Answer 5

If there was water on both sides. I believe the water pressure would equalize then boil off rapidly then more slowly or until the earth's core was totally cooled.