# Why is the Chilean mine 90 degrees? **URL:** \ **Category:** Factual Questions\ **Created:** [October 13, 2010, 8:27pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-90-degrees/557046 "2010-10-13T20:27:40Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Rusalka](https://avatars.discourse-cdn.com/v4/letter/r/ecd19e/32.png) [@Rusalka](https://boards.straightdope.com/u/Rusalka)\ **Post date:** [October 13, 2010, 8:27pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-90-degrees/557046/1 "2010-10-13T20:27:40Z")
Is it near volcanic activity? I thought temperature underground is usually 50 degrees. ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [October 13, 2010, 8:33pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-90-degrees/557046/2 "2010-10-13T20:33:51Z")
Free of humans generating heat, it would be cooler. I believe the whole issue is that a few dozen guys are (were) stuck in an area with minimal ventilation/circulation. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [October 13, 2010, 8:45pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-90-degrees/557046/3 "2010-10-13T20:45:17Z")
> [@Rusalka](#): > > Is it near volcanic activity? I thought temperature underground is usually 50 degrees. The temperature at some relatively shallow depth is stable year-round at something like 50 degrees F, but as you go deeper, the temperature steadily rises. The miners are very deep, at a depth of something like 2,300 feet (700 meters). The heat has nothing to do with volcanic activity in the vicinity, just the usual heat from the Earth’s mantle (and core) below. This [cite](http://www.madsci.org/posts/archives/2002-03/1017275290.Es.r.html) states that in the upper crust, temperature increases with depth by about 25 degrees C per kilometer (72 degrees F per mile). ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [October 13, 2010, 8:46pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-90-degrees/557046/4 "2010-10-13T20:46:22Z")
> [@Philster](#): > > Free of humans generating heat, it would be cooler. > > I believe the whole issue is that a few dozen guys are (were) stuck in an area with minimal ventilation/circulation. I expect this is part of it, too, especially with respect to the humidity. ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [October 13, 2010, 8:54pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-90-degrees/557046/5 "2010-10-13T20:54:40Z")
They also have lights I’m sure, which also create heat. ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [October 13, 2010, 9:22pm UTC](https://boards.straightdope.com/t/why-is-the-chilean-mine-90-degrees/557046/6 "2010-10-13T21:22:56Z")
What **Robby** said. Here’s a relevant wikipedia page: [Geothermal gradient - Wikipedia](http://en.wikipedia.org/wiki/Geothermal_gradient) Some of the _really_ deep mines in places like South Africa that go miles down are hellishly hot and require heavy duty air conditioning to even make it livable at depth.