Geothermal activity

Geothermal activity is a group of natural heat transfer processes, occurring on Earth's surface, caused by the presence of excess heat in the subsurface of the affected area. Geothermal activity can manifest itself in a variety of different phenomena, including, among others, elevated surface temperatures, various forms of hydrothermal activity, and the presence of fumaroles that emit hot volcanic gases. 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 or gases. Fumaroles, or volcanic vents, are holes in the ground from which volcanic vapors and gases escape to the atmosphere. Geothermally active areas are often located over an active magma chamber, which constantly releases hot gases 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 fall out of suspension when the volcanic gases cool to the air. Ice cauldrons are a feature that occurs when an ice cap is affected by geothermal heating, either from active volcanism or the continuous heat production from an active geothermal area. Ice cauldrons can have many different appearances. These range from a smooth dent in the ice cap to deep holes with very steep walls formed by concentric rings of crevasses. The width of ice cauldrons can range from 50 meters up to around 10 kilometers, while depth can range from several meters to hundreds of meters. The shape of the cauldron can be stable or highly variable, and is not related to the nature of the underlaying heat source.