Geothermal activity

Geothermal activity is activity on the surface that is caused by the presence of excess heat in the subsurface of an area.[2] Geothermal activity most often manifests itself in the form of:

  • Fumaroles & Vents as emitters of volcanic gases with elevated temperatures;
  • Hydrothermal activity: hot springs and geysers, geothermal increase in water temperature of reservoirs and rivers;
  • Areas with elevated surface temperatures due to geothermal heating, for example resulting in a partially snow-free landscape during winter.
  • In areas with permafrost, it leads to growth of taliks and thermokarst, in the case of partial geothermal heating, leads to a decrease of the permafrost depth.
Geysir, a geyser in Iceland, after which the phenomenon is named.[1]

Background physics
Main article: Earth's internal heat budget

Geothermal activity mostly appears in volcanic provinces, in some cases it can be caused by underground fires or by large deposits of radioactive elements. Other sources of internal heating can be gravitational differentiation of substances, tidal friction, metamorphism, or phase transitions. The release of heat to the surface occurs either in the form of a conductive heat flow, or in the form of convective heat transfer by groundwater, gases or lava.[3]

Fumaroles & Vents
A fumarole, the orange and yellow colouration is from minerals that are deposited by the superheated fumes as they cool to normal temperatures

Fumaroles, or Volcanic vents, are holes in the ground from which volcanic vapors and gasses escape to the atmosphere. Geothermally active areas are often located over active magma chamber, which constantly releases hot gasses that travel to the surface through cavities in the rock. Where these cavities reach the surface they form fumaroles. areas where these vents are concentrated are known as Fumarole fields. Fumaroles tend to form concentrated deposits of sulfuric minerals, which are deposited when the volcanic gasses cool to the air.[4]

Hydrothermal activity

Geothermal heat and groundwater can interact in several ways.

geysers

geysers are the most well known hydrothermal feature. they occur when groundwater in underground cavities becomes superheated under a lid of colder surface water. When the superheated water breaches the surface, it flashes to steam, causing the pressure below it to suddenly drop, which causes a chain reaction where most of the water in the geyser's feed system flashes to steam all at once.

There are two main types of geyser. Fountain geysers, which erupt in violent bursts from a pool, and cone geysers, which erupt in steady jets for minutes at a time from a sinter cone of siliceous material that has been deposited surrounding the main vent. [5]

Hot spring in Waiotapu, New zealand.

hot springs and mud pots

In other areas, the heated groundwater gathers in pools, forming hot springs.[6] Where very little groundwater is available, rising hot groundwater in combination with microbial activity leads to the formation of mud pots.[7]

References
  1. "geyser | Etymology, origin and meaning of geyser by etymonline". www.etymonline.com. Retrieved 2023-03-23.
  2. "Лаборатория тепломассопереноса // Геологический институт РАН". geotherm.ginras.ru (in Russian). Retrieved 2023-03-22.
  3. "Геотермальная активность // ГОСТ 19431-84 ГОСТ 21027-75 ГОСТ 32144-2013 ГОСТ 24291-90 ГОСТ Р 57114-2016 ГОСТ 19880-74". www.panpwr.ru (in Russian). Retrieved 2023-03-22.
  4. Philpotts, Anthony R. (2009). Principles of igneous and metamorphic petrology. Jay J. Ague (2nd ed.). Cambridge, UK: Cambridge University Press. ISBN 978-0-521-88006-0. OCLC 231581100.
  5. Park, Mailing Address: PO Box 168 Yellowstone National; Us, WY 82190-0168 Phone: 307-344-7381 Contact. "Hydrothermal Features - Yellowstone National Park (U.S. National Park Service)". www.nps.gov. Retrieved 2023-04-02.
  6. O'Banion, K.; Hall, C. (1980-07-14). "Geothermal energy and the land resource: conflicts and constraints in The Geysers-Calistoga KGRA". {{cite journal}}: Cite journal requires |journal= (help)
  7. Dahlquist, G. R.; Cox, A. D. (2016-12-01). "What's in the mud?: Water-rock-microbe interactions in thermal mudpots and springs". 2016: B21E–0469. {{cite journal}}: Cite journal requires |journal= (help)
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.