Changes

=== Remaining heat and radioactive heat ===

=== Remaining heat and radioactive heat ===

* '''Geothermal Gradient''' is the variation of temperature according to a rock's depth. It is read in Celsius or Fahrenheit grades by the unit of vertical distance.  

* '''Geothermal Gradient''' is the variation of temperature according to a rock's depth. It is read in Celsius or Fahrenheit grades by the unit of vertical distance.  

* '''Surface Heat Flow''' is the heat that continuously comes up to the surface. It is read in joules per second. It is estimated that the average is 42 x 1012 J/sec and has two different sources:

* '''Surface Heat Flow''' is the heat that continuously comes up to the surface. It is read in joules per second. It is estimated that the average is 42 x 1012 J/sec and has two different sources (See [[:File:Figure 1.png|Figure 1]]<ref name=Electropaedia>[http://www.mpoweruk.com/geothermal_energy.htm Electropaedia]</ref>):

** '''Remaining heat release''': 34 x 1012 J/sec. It comes from the [[mantle]] and the nucleus and is the heat remaining after the formation of the planet.

** '''Remaining heat release''': 34 x 1012 J/sec. It comes from the [[mantle]] and the nucleus and is the heat remaining after the formation of the planet.  

** '''Radioactive heat release''': 8x1012 J/sec. It comes from the [[crust]] and is produced by the fission of radioactive isotopes. See [[:File:Figure 1.png|Figure 1]]

** '''Radioactive heat release''': 8 x 1012 J/sec. It comes from the [[crust]] and is produced by the fission of radioactive isotopes.  

[[File:Figure 1.png|center|{{figure number|1|}}Remaining heat and radioactive heat [http://www.mpoweruk.com/geothermal_energy.htm].]]

[[File:Figure 1.png|center|{{figure number|1|}}Remaining heat and radioactive heat<ref name=<ref name=Electropaedia />.]]

=== Igneos phenomena ===

=== Igneos phenomena ===

In certain regions the geotermal gradient can be increased considerably due to magmatic process (Figure 2).Most of the áreas of goethermal interest are situated in volcanic regions.In many places of our planet,hydrotermal evidence can be seen on the surface provided that geologial conditions are favourable.[[File:Strokkur Geyser,Iceland.png|200|thumbnail|center|Figure 2: Igneos phenomena Strokkur Geyser,Iceland [http://www.stewartsmithphotography.co.uk/shop/uncategorized/strokkur-geysir-national-park-iceland/]. ]]

In certain regions the geothermal gradient can be increased considerably due to the magmatic process ([[:File:Strokkur Geyser,Iceland.png|Figure 2]]). Most of the areas of geothermal interest are situated in volcanic regions. In many places of our planet, hydrothermal evidence can be seen on the surface, provided that geological conditions are favorable.

[[File:Strokkur Geyser,Iceland.png|400px|thumbnail|center|{{figure number|2|}}Igneous phenomenon the Strokkur Geyser in Iceland<ref>http://www.stewartsmithphotography.co.uk/shop/uncategorized/strokkur-geysir-national-park-iceland/ Stewart Smith Photography</ref>. ]]

=== Plate Tectonics and heat distribution ===

=== Plate Tectonics and heat distribution ===