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Hole Drilled to Bottom of Earth's Crust
AtariAmarok writes "A new article is up on LiveScience about a hole drilled into the Earth's crust to explore the layers of our planet's substrate. The hole gets closer to the mantle than any other efforts that have gone before. The hole might reach the "Moho" (division between Earth's brittle outer crust and the hotter, softer mantle) within a few years." From the article: "The depth of the Moho varies. This latest effort, which drilled 4,644 feet (1,416 meters) below the ocean seafloor, appears to have been 1,000 feet off to the side of where it needed to be to pierce the Moho, according to one reading of seismic data used to map the crust's varying thickness."
That's happening all the time on the sea floor, where the plates are slowly separating.
A bunch of lava will squish out, immediatly cool, and plug the hole, and they'll have to start all over again.
Kind of like Cool Hand Luke.
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and opening a hole will relieve that pressure and cause a large amount of it to flow out?
Why, yes, that can happen. Mind you, "large" is only on the human scale, and this is hardly an unusual circumstance.
What is essetnially (but not actually) mantle-juice flows out onto the crust on a somewhat irregular basis. I'm sure you've heard of it, it's quite specatcular when molten rock et al flow out.
As for a "large ammount" -- us drilling into the mantle is like us sticking a very large straw into the ocean. Sure, the water down at the bottom is under pressure, and it will shoot up the straw if we let it. But the ocean certainly isn't going anywhere.
EOS covered this recent work just recently. The problem with offset drilling is that it does not provide the same informatio as a continuous core. These cores are obtained from 'windows' in previous flows and there is a problem with correlation between boreholes when horizons are not sampled widely. This complicates the historical interpreation and genesis of the oceanic crust.
The demand for advanced drilling technology is one problem with the current Moho sampling efforts. Exploration drilling of the kind used for oil production is not well suited for the work that the ODP is engaged in. Bit designs for the lithostatic loads that these dense rocks develop at depth require a different approach than those used to drill continental sediments buried at depth beneath the ocean.
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well -- i don't know if that would really be "artificial," then, since that is how many islands are formed, especially along convergent plate boundries. it is exactly as happens it happens with "hot spots." the issue would be making the hole large enough and keeping the hole open, since it would fill up pretty quickly and just make a little mountain under the sea.
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You need Advanced Ecological Engineering to get 3+ minerals from a single tile, though. Until then, you're stuck at 2.
Here's a diagram of Earth's layers:% 20tectonics/Earthcore.jpg
http://earth.usc.edu/~stott/Catalina/images/plate
My only question is what if the enormous amount of pressure from the mantle forced tons of lava to shoot into the ocean? Or in reverse what if the pressure of the ocean was greater and we open a giant drain in the middle of the atlantic?
Would the lava/water contact just harden to rock instantly and allow nothing more through?
Probably quite ignorant fears, but still worth asking.
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But how smart is drilling into the core of the earth? Aren't they asking for one huge volcano?
No, as magma is coming up to the surface all the time all over the world in holes much, much larger than the borehole.
If someone who was hell bent on one HUGE suicide bomb, what is to stop a country from picking 4 or 5 places around the world, dig deep, and pack a nuke. Blow up the nuke, and the earth is rearranged.
Nothing much would happen. The energy already being released by normal volcanoes and earthquakes is far more than we could produce with nuclear weapons. For example, the Mount St. Helens volcano released energy in just one day (18 May 1980) equivalent to 400 million tons of TNT - about 20,000 Hiroshima bombs. That is a significant fraction of the entire world's current nuclear arsenal - from just one volcano! A few nukes exploded around the world is not going to do anything.
Aren't they asking for one huge volcano?
No. Well, maybe in the movies.
Think about it for a second. All over the world there a thousands of holes that already lead to the molten material, and yes- they are volcanoes.
BUT, how many of those are constantly spewing molten rock? Relatively few. And some of those are so consistent in their eruptions people live on them. Hawaii for one, Iceland another.
When a volcano like Tambora (largest recent) or even Fish Canyon or Yellowstone (28 million and 1.3 million YA, respectively) went off, the earth wasn't "rearranged." Sticking a nuke in a relatively tiny hole wouldn't even really have a major impact on the local area. It certainly wouldn't cause the kind of damage you're talking about. How many times have nukes been tested underground, or even above? The damage to the earth was minimal. It was all the things around the blast that suffered damage.
Worst case scenereo and the USA is relocated to the moon.
Unlikely, Fish Canyon only ejected about 5000 cubic kilometers and it was in the USA which is, obviously, still here.
R(k)
Unlikely. The Mohorovicic (Moho) discontinuity can be described in a few different ways - either where seismic veolocities have a marked discontinuity, or where a noticable chemical/mineralogical change occurs (can't remember what it is, I'm a geophysicist, not a geologist). What it's not is a boundary between a nice solid crust floating on top of "firey liquid mantle". In fact more accurate terms are lithosphere and asthenosphere, rather than crust and mantle, which basically differentiate between rigid, colder material, and warmer, more ductile rock. The top of the mantle is still solid, but becomes increasingly ductile with depth. Various minerals reach melting point as you go down towards the Core-Mantle Boundary, but basically I think you have to get to the outer core before it's all liquid (mostly iron). In terms of energies, the largest nuclear bomb ever detonated was about 55-60 megatonnes (depending on who you ask), in 1961 by the USSR. The energy released by the great 1960 Chilean earthquake (the largest recorded in the last 100 years) was equivalent approximately to a 2000 Mt bomb. So, setting off a nuke at the moho might temporarily create a small spherical cavity which would probably collapse in on itself, and maybe create some melt, but it's doubtful it would come gushing to the surface as a raging plume of "liquid hot magma". Besides, there have been plenty of underground nuclear tests, and none of those have resulted in a humungous volcano. As yet. The USGS site at http://www.usgs.gov/ is probably a good place to find out more.
The mantle is under pressure because of the rock piled on top of it. It is not, as is sometimes believed, molten. And it won't goosh out like champagne when the cork is popped. Volcanoes do sometimes behave this way, but that's because they are isolated pockets of molten, gas-infused rock. When the confining pressure is removed, they do in fact goosh out lava like champagne. But that's a very different story.
The stuff that comes out of volcanoes is not pure mantle material. In fact, usually it's melted crustal material. Or some mixture of mantle and crustal material. Only occasionally do volcanoes cough up a hunk of mantle. More usually, we can look at pieces of mantle that may have gotten caught up in some tectonic process and been uplifted for us to see. But that's rare, and the rocks are often altered by other processes.
Shouldn't you instead be comparing the energy released by normal volcanoes and the energy released by volcanoes initiated by a manmade charge (if indeed a charge in such a bore-hole could produce any such effect)?
No, because energy is energy! individual pressure releases from magma chambers can be pretty much equivalent to the effect of nuclear explosions.
If it were possible, for example, to crash the fault in the Bahamas with a nuclear charge, the resultant super-tsunami would also cause more damage to the US than the original explosion(s) relocated from the Bahamas to the US east-coast would, wouldn't it?
Well, yes, but that is not what the original poster was saying. This would neither produce a man-made volcano, or would it 'blow the USA to the moon'.
Also, how would you 'crash' the fault?
To quote from the California Geological Survey:
"..the use of a nuclear explosion to cause or prevent a significant earthquake is considered science fiction." A nuke can create very minor earth tremors, but the main effect is to liquefy rock and create a big hole.
yes, but that's not the point.
A single continuous drill hole ~2600m long is a very difficult thing to do. Many things can go wrong to block the hole or damage the drill string forcing abandonment of the hole.
Mine workings like the South African example are not easy by anymeans, but are very feasible since you are advancing 10 feet or so at a time in , shoring up everything as you go, and can easily replace any broken equipment, and work around most ground problems.
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Cannikin - a 5 megaton ABM warhead detonated underground in Alaska - caused the equivalent of a 6.5+ earthquake, with part of the island it was detonated under being permanently raised, and a long section of coastline falling into the sea.
The CGS and USGS play this down a bit, and I'm not entirely sure why.
Because this did not happen. There was no earthquake. There was a ground wave produced by the blast which, close to the site, was similar to the ground wave which would have been detected over a much wider area if there had been an earthquake, but there was no quake, either locally or elsewhere.
Of course a small part of the island close to the blast was raised - this is what happens with underground explosions! But, the main effect was a 40-foot deep crater. As for a section of the coastline falling into the sea - I can find no evidence or reports of this anywhere.
Drilling two miles isn't that hard and has certainly been done before. The deepest drill hole on land goes down some 12 km.
But this isn't the same thing. This is trying to drill down 3+ km below the bottom of the Atlantic. In this case the drilling starts under 750 m of water (and only because Atlantis Massif is a relatively high spot on the sea floor). The mid-ocean ridge in the Atlantic is their target because it has some of the shallowest Moho in the world. To reach the Moho from a continental section you would probably have to drill 25 km or more even with a good choice of location.
If you do, then you should review some basic physics concepts. The pressure differential that exists between the water on top of the ocean and at the bottom would also exist between the bottom of the pipe and the top. So you would have exactly the same level of water inside your straw, as you would outside. Just like in a bottle of Coke or something. Putting one end of the straw at the bottom of the bottle doesn't cause the soda to come shooting out the other end towards your face (although it would be funny if it did, wouldn't it?).
The only exception is if you were to lower the 'straw' down while filled with air (by keeping the top closed and equalizing the pressure against the water using compressed air) and then when you got down to the desired depth, releasing the cap on top -- this would cause water to rush in the bottom to equalize the fluid levels between the inside and outside of the pipe. If the differential is big enough it may in fact be moving quickly enough to 'overshoot' the water level of the ocean and come out the top of the pipe, but this is temporary only -- the steady state solution is with both fluid levels equal.
If you don't believe me, go get a clear straw and a glass of water and come back when you've tried it.
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There were many, many aftershocks after the main one. It's been about a decade since I took a geology course, but I have difficulty envisioning how this could occur if there wasn't some sort of tectonic activity involved.
There was no shock! It was a local ground wave, not an earthquake. There may have been slight aftershocks at the site, as rock caved in to the hole generated by the blast. There were no earthquakes, and no tectonic activity - the blast was 5 megatons, which is absolutely negligible compared to the energy in even the smallest quake.
You can see footage of it in Atomic Journeys (the third film in the "Trinity and Beyond" series). It also has some excellent shots of the huge cracks opened by Faultless.
Well, big bombs will open cracks, but these are nothing on the scale of tectonic events.
I have not seen the film, but I don't rate a single movie narrated by William Shatner as a definitive source of scientific information. It may be true, but I don't consider that useful evidence.
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Way to skim over my post and the grandparent's post and miss what I was commenting on previously. My last post was in repsonse to the statement "The pressure outside the balloon is the same as the pressure inside the balloon". I don't think that's true if the balloon wants to pop when you stab it with something. An uninflated balloon is the only kind with equal pressure inside and out.
Yeah, that's the yellowstone supervolcano. Its has errupted roughly every 620,000 years, and the last one was 640,000 years ago, and last time it errupted it poured out roughly 8000 times as much ash as Mount St. Helens did in the 1980 erruption. It is estimated that if it goes again in the near future it would cover most of the US within 1000 miles of yellowstone in a thick layer of ash, killing more that 20 million Americans. It would also cause a global temperature drop of up to 10 degees C causing a new mini ice age for as long as 10 years during which time much of the worlds population would simply starve to death. I suspect we would be lucky to see as few as 1 Billion fatalities worldwide, together with the massive social and political fallout that would bring.
The problem is that no one could know whether attempting to cause a small erruption now would in fact just trigger the real thing, because vulcanology is not an exact science, and we simply don't know enough to do such a thing.
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