# How deep a hole could we dig into the Earth? **URL:** \ **Category:** Factual Questions\ **Created:** [December 9, 2011, 12:37pm UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611 "2011-12-09T12:37:07Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [December 10, 2011, 1:31pm UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/21 "2011-12-10T13:31:24Z")
You could blast a crack in the surface rock with a hydrogen bomb, pour in a hundred thousand tonnes of molten iron, and let it sink to the Earth’s core, although that technically wouldn’t count as a hole. > **[David J. Stevenson](https://en.wikipedia.org/wiki/David_J._Stevenson)** > > David John Stevenson (born 2 September 1948) is a professor of planetary science at Caltech. Originally from New Zealand, he received his Ph.D. from Cornell University in physics, where he proposed a model for the interior of Jupiter. He is well known for applying fluid mechanics and magnetohydrodynamics to understand the internal structure and evolution of planets and moons. > Stevenson's tongue-in-cheek idea about sending a probe into the earth includes the use of nuclear weapons to crack the ... ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [December 10, 2011, 1:34pm UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/22 "2011-12-10T13:34:12Z")
> [@Leo\_Bloom](#): > > But I, like my dog with his bone, want simply to dig a hole to China, as is commonly said. > I live in NYC. Which way do I go? Bowery to Canal st. Oh, you said _China_, not Chinatown. Never mind. 😛 ---
**Author:** ![UncleFred](https://avatars.discourse-cdn.com/v4/letter/u/f0a364/32.png) [@UncleFred](https://boards.straightdope.com/u/UncleFred)\ **Post date:** [December 10, 2011, 1:57pm UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/23 "2011-12-10T13:57:23Z")
> [@MichaelEmouse](#): > > So, with today’s technology and lots of labor and resources, how deeply could I go into the Earth? What would it entail? So, just to nitpick, there is a big difference between how deep a hole you could drill (most of the responses) and “how deep could I go?” Not too far down the heat would do you in. The open pit proposed in one response might circumvent the temperature, but I suspect that maintaining the angles of the side would result in a’wide’ hole at the top ; roughly twice the depth, which sounds less achievable then the hole-drilling. ---
**Author:** ![BMalion](https://avatars.discourse-cdn.com/v4/letter/b/e274bd/32.png) [@BMalion](https://boards.straightdope.com/u/BMalion)\ **Post date:** [December 10, 2011, 2:04pm UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/24 "2011-12-10T14:04:56Z")
Pellucidar? ---
**Author:** ![ExTank](https://avatars.discourse-cdn.com/v4/letter/e/35a633/32.png) [@ExTank](https://boards.straightdope.com/u/ExTank)\ **Post date:** [December 10, 2011, 4:31pm UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/25 "2011-12-10T16:31:19Z")
> [@BMalion](#): > > Pellucidar? [Pellucidar or bust!](http://fantasyartdesign.com/free-wallpapers/imgs/mid/Pellucidar%20or%20Bust-m.jpg) ---
**Author:** ![Corresponder](https://avatars.discourse-cdn.com/v4/letter/c/22d042/32.png) [@Corresponder](https://boards.straightdope.com/u/Corresponder)\ **Post date:** [December 12, 2011, 5:55am UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/26 "2011-12-12T05:55:32Z")
Once you dug down 20 or 30 miles through the crust you would reach the mantle, which I believe is a quicksand-like material, so anything dug deeper would keep filling in unless you lined it with something like a pipe or concrete wall. Of course even when you reached the water table less than a mile below ground you would have water filling in the hole as you dug, and would need some sort of pump to maintain a true hole. ---
**Author:** ![Snarky\_Kong](https://avatars.discourse-cdn.com/v4/letter/s/a183cd/32.png) [@Snarky\_Kong](https://boards.straightdope.com/u/Snarky_Kong)\ **Post date:** [December 12, 2011, 6:38am UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/27 "2011-12-12T06:38:02Z")
> [@coremelt](#): > > [http://www.csmonitor.com/USA/Politics/DC-Decoder/2010/0610/Drilling-for-oil-with-nuclear-weapons-The-US-has-done-it](http://www.csmonitor.com/USA/Politics/DC-Decoder/2010/0610/Drilling-for-oil-with-nuclear-weapons-The-US-has-done-it) That wasn’t them digging holes, that’s just increasing the permeability of the rock. Fracking on steroids. ---
**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\ **Post date:** [December 12, 2011, 6:49am UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/28 "2011-12-12T06:49:22Z")
Well, how wide and deep could a circular open pit get? 10 km deep and 20 km across? 100 km deep and 200 km across? (Let’s ignore costs and feasibility of digging this much; I’m just wondering about rock strength.) ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [December 12, 2011, 7:25am UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/29 "2011-12-12T07:25:13Z")
> [@Snarky\_Kong](#): > > That wasn’t them digging holes, that’s just increasing the permeability of the rock. Fracking on steroids. Well, this is sort of a nitpick, but the idea was that the bomb would also increase the porosity of the rock by making a huge underground cavity. As it turns out, in addition to the other obvious problems, it really didn’t work very well either for making underground cavities or fracturing rock. Good old fashioned hydrofracking worked better! To give you an idea, the last US PNE test (Rio Blanco) tried to use three 33kt bombs to make an 800 x 40 foot high cylindrical “chimney” and failed-- the three individual cavities weren’t big enough and failed to join. So you had three bombs, each twice as powerful as the Hiroshima bomb, and they couldn’t even get 800 feet. And that was at a depth of only about 6000 feet-- like I mentioned above the effectiveness goes down with depth. So I think we can probably rule out that particular method. But here’s a cool picture of someone walking around in a cavity made by a much smaller, much shallower test: [Project Gnome | Lawrence Livermore National Laboratory's Pro… | Flickr](http://www.flickr.com/photos/llnl/3084459187/in/photostream/) ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [December 12, 2011, 8:52am UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/30 "2011-12-12T08:52:42Z")
> [@Sunspace](#): > > Well, how wide and deep could a circular open pit get? 10 km deep and 20 km across? 100 km deep and 200 km across? (Let’s ignore costs and feasibility of digging this much; I’m just wondering about rock strength.) If the slope is shallow enough, you can dig as much as you want. Just hope it doesn’t rain. ---
**Author:** ![Lobohan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobohan/32/79_2.png) [@Lobohan](https://boards.straightdope.com/u/Lobohan)\ **Post date:** [December 12, 2011, 9:00am UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/31 "2011-12-12T09:00:38Z")
Say you spend your ten billion dollars on power plants for a laser? Could a laser with fast exhaust fans to suck up vaporized debris possibly work? ---
**Author:** ![Snarky\_Kong](https://avatars.discourse-cdn.com/v4/letter/s/a183cd/32.png) [@Snarky\_Kong](https://boards.straightdope.com/u/Snarky_Kong)\ **Post date:** [December 12, 2011, 11:56am UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/32 "2011-12-12T11:56:56Z")
> [@GreasyJack](#): > > Well, this is sort of a nitpick, but the idea was that the bomb would also increase the porosity of the rock by making a huge underground cavity. As it turns out, in addition to the other obvious problems, it really didn’t work very well either for making underground cavities or fracturing rock. Good old fashioned hydrofracking worked better! > > To give you an idea, the last US PNE test (Rio Blanco) tried to use three 33kt bombs to make an 800 x 40 foot high cylindrical “chimney” and failed-- the three individual cavities weren’t big enough and failed to join. So you had three bombs, each twice as powerful as the Hiroshima bomb, and they couldn’t even get 800 feet. And that was at a depth of only about 6000 feet-- like I mentioned above the effectiveness goes down with depth. So I think we can probably rule out that particular method. But here’s a cool picture of someone walking around in a cavity made by a much smaller, much shallower test: [Project Gnome | Lawrence Livermore National Laboratory's Pro… | Flickr](http://www.flickr.com/photos/llnl/3084459187/in/photostream/) I was under the impression that it did work well, although not nearly as well as hoped and they also never solved the issue of radioactive contamination in the recovered oil/water. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [December 12, 2011, 12:32pm UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/33 "2011-12-12T12:32:42Z")
From Wikipedia’s page on the [Kola Superdeep](http://en.wikipedia.org/wiki/Kola_Superdeep_Borehole)hole: > [@](#): > > In 1983, the drill passed 12,000 m (39,000 ft), and drilling was stopped for about a year to celebrate the event. Well, those Russkis sure as hell know how to have a party. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [December 12, 2011, 12:40pm UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/34 "2011-12-12T12:40:37Z")
> [@coremelt](#): > > An alien race buries a hypernova bomb 100 km deep in the upper mantle. We have 1 year to reach it and defuse it. > > Can we do it? No. No, we can’t. We might be able to better the current record by some sizeable fraction, in terms of depth. But not in a year. Kola took \*\*19 years \*\*to reach maximum depth And 100km is just unthinkable. ---
**Author:** ![bahimes](https://avatars.discourse-cdn.com/v4/letter/b/e36b37/32.png) [@bahimes](https://boards.straightdope.com/u/bahimes)\ **Post date:** [December 12, 2011, 12:50pm UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/35 "2011-12-12T12:50:21Z")
> [@Alessan](#): > > If the slope is shallow enough, you can dig as much as you want. Just hope it doesn’t rain. I recall the Angle of Repose (for calculating whether the sides of a trench or hole must be shored up) for sand is 34 degrees. This would require a hell of big beach (Sahara) to get any kind of depth at all. ---
**Author:** ![coremelt](https://avatars.discourse-cdn.com/v4/letter/c/4491bb/32.png) [@coremelt](https://boards.straightdope.com/u/coremelt)\ **Post date:** [December 12, 2011, 12:50pm UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/36 "2011-12-12T12:50:54Z")
> [@MrDibble](#): > > No. No, we can’t. > . ok, could we do 30 km in a year? ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [December 12, 2011, 12:57pm UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/37 "2011-12-12T12:57:35Z")
> [@coremelt](#): > > ok, could we do 30 km in a year? No - once again - Kola took 19 years to get to 12 km. You’re talking more than double that, bearing in mind that the rate is probably a victim of diminishing returns. Plus the 1000 deg. C rock, of course… ---
**Author:** ![Koxinga](https://avatars.discourse-cdn.com/v4/letter/k/4af34b/32.png) [@Koxinga](https://boards.straightdope.com/u/Koxinga)\ **Post date:** [December 12, 2011, 2:05pm UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/38 "2011-12-12T14:05:41Z")
What about a huge titanium or depleted uranium rod dropped from orbit? Could it punch its way through the crust? ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [December 12, 2011, 2:10pm UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/39 "2011-12-12T14:10:05Z")
> [@Koxinga](#): > > What about a huge titanium or depleted uranium rod dropped from orbit? Could it punch its way through the crust? Naah. It’s too elastic. Basically, to get that deep, you need a planet-killer-type impact event. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [December 12, 2011, 2:17pm UTC](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611/40 "2011-12-12T14:17:55Z")
> [@MrDibble](#): > > … > > And 100km is just unthinkable. We’re thinking about it. 🙂 [Previous page](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611.md?page=1) [Next page](https://boards.straightdope.com/t/how-deep-a-hole-could-we-dig-into-the-earth/605611.md?page=3)