# Why is the Chilean mine so hot? **URL:** \ **Category:** Factual Questions\ **Created:** [August 24, 2010, 3:10pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-so-hot/551295 "2010-08-24T15:10:37Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [August 24, 2010, 3:10pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-so-hot/551295/1 "2010-08-24T15:10:37Z")
News reports about the trapped miners in a Chilean copper mine are saying that the room where the miners are is around 90 degrees. This is at a depth of about half a mile. I’ve been in the Soudan iron mine in northern Minnesota, at a depth of about a mile; the temperature was around 50 degrees. I understand gold mines in South Africa that operate at depths of approximately two miles have to pump in refrigerated air to make the place habitable for the miners, but neither the Soudan mine nor the Chilean mine run nearly that deep. If things are cool at a depth of 1 mile (in Minnesota), why are they so warm at a depth of a half-mile in Chile? Is there geothermal activity in the area? ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [August 24, 2010, 3:28pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-so-hot/551295/2 "2010-08-24T15:28:16Z")
I have no idea about any particular mine but it should be noted that the earth’s crust is not uniformly thick. Some places magma is closer to the surface than others. Sometimes it can be very close. ---
**Author:** ![Buck\_Godot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/buck_godot/32/6573_2.png) [@Buck\_Godot](https://boards.straightdope.com/u/Buck_Godot)\ **Post date:** [August 24, 2010, 3:42pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-so-hot/551295/3 "2010-08-24T15:42:43Z")
Nevermind ---
**Author:** ![Ale](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@Ale](https://boards.straightdope.com/u/Ale)\ **Post date:** [August 24, 2010, 4:11pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-so-hot/551295/4 "2010-08-24T16:11:20Z")
Well, keep in mind that they have been trapped in a relatively confined space for many days, all that body heat should surely add up over time. ---
**Author:** ![Skammer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/skammer/32/143_2.png) [@Skammer](https://boards.straightdope.com/u/Skammer)\ **Post date:** [August 24, 2010, 5:23pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-so-hot/551295/5 "2010-08-24T17:23:30Z")
Are they cooling the air that gets pumped down to the miners? I heard that the mine is on the edge of a desert, and presumably they are pumping fresh air down there now. If the air is not being chilled first it would presumably be pretty warm. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [August 24, 2010, 5:31pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-so-hot/551295/6 "2010-08-24T17:31:21Z")
in some report they are in a spiral tunnel that is blocked higher up from the survival chamber is. they had been using internal combustion engine equipment in the area, so the airspace near them much be huge. i don’t have a cite for the info. as i recall they are at some midpoint between the spiral shaft bottom and the blockage. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [August 24, 2010, 5:50pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-so-hot/551295/7 "2010-08-24T17:50:49Z")
I’m nort finding a decent geothermal map of Chile, [however](http://geothermal.marin.org/map/andean.html): > [@](#): > > The Andes run the length of the west coast of South America from western Venezuela through Columbia, Ecuador, Peru, Bolivia, Chile and Argentina. Subduction of the Nazca plate under the South American plate has produced many active and recently-active volcanoes. Several high-temperature geothermal systems occur in these sparsely populated areas There are [volcanoes](http://www.visitchile.com/eng/atacama-desert-altiplano/destination.asp?id=432) and [hot springs](http://www.chile-attractions.com/hot-springs-in-chile.html#Hot%20Springs%20In%20Chile,Atacama) within 100 miles of Copiapo, so there’s hot rock near the surface in the area. Incidentally, the 27th level of [Soudan mine in Minnesota](http://www.squidoo.com/soudan-mine-tour-minnesota), where they give the tours and keep the neutrino detector, is only 2,341 feet below ground, roughly half a mile. Tour guides say that the lower levels are flooded. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [August 24, 2010, 6:33pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-so-hot/551295/8 "2010-08-24T18:33:27Z")
Here’s another unpleasantly warm underground location: > [@](#): > > Cave of the Crystals or Giant Crystal Cave (Spanish: [Cueva de los Cristale](http://en.wikipedia.org/wiki/Cave_of_the_Crystals)s) is a cave connected to the Naica Mine 300 metres (980 ft) deep in Chihuahua, Mexico. The main chamber contains giant selenite crystals, some of the largest natural crystals ever found.[1] The cave’s largest crystal found to date is 11 m (36 ft) in length, 4 m (13 ft) in diameter and 55 tons in weight. The cave is 27 m (89 ft) in length and 9 m (30 ft) in width. The cave is extremely hot with air temperatures reaching up to 58 °C (136 °F)[2] with 90 to 100 percent humidity. ---
**Author:** ![ivn1188](https://avatars.discourse-cdn.com/v4/letter/i/e480ec/32.png) [@ivn1188](https://boards.straightdope.com/u/ivn1188)\ **Post date:** [August 25, 2010, 5:50pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-so-hot/551295/9 "2010-08-25T17:50:52Z")
Most deep mines are very warm. The two big sources of heat in mines are the rock (warmed by heat from deeper), which heats up the air, and autocompression. Groundwater, etc, can affect the temp of shallow mines, but below a few hundred feet, it’s pretty much that deeper = warmer. There are very few mines “near” magma sources, though some areas of the crust are warmer than others. Also, nearby water flows can affect the temperature. Deep mines are almost uniformly warm to hot, though. The second source of heat is the compression of the air sent into the mines. Since the mine is so deep, the column of air is heavier, increasing the air pressure inside the mine. This increases the temperature of the air as well. Finally, almost all of the energy from drilling, blasting, machinery, etc, ends up in the rock, warming it.