![cover image](https://wikiwandv2-19431.kxcdn.com/_next/image?url=https://upload.wikimedia.org/wikipedia/commons/thumb/8/82/S04_130_Solfatara%252C_Fumarole.jpg/640px-S04_130_Solfatara%252C_Fumarole.jpg&w=640&q=50)
Geothermal activity
Activity resulting from underground heat / From Wikipedia, the free encyclopedia
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, usually caused by the presence of an igneous intrusion underground.[2] 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.
![A rocky surface with a mound centrally in the image. The mound has holes in the top. Surrounding rocks have been stained orange and yellow. There is smoke or steam rising from the top.](http://upload.wikimedia.org/wikipedia/commons/thumb/8/82/S04_130_Solfatara%2C_Fumarole.jpg/640px-S04_130_Solfatara%2C_Fumarole.jpg)
![A green landscape with a platform of grey rock. steam is rising from a pool or hole in the middle of the platform](http://upload.wikimedia.org/wikipedia/commons/thumb/8/88/Great_Geysir_%282%29.jpg/640px-Great_Geysir_%282%29.jpg)