Mud volcano
The geothermal
Geothermal is related to energy and may refer to:* The geothermal gradient and associated heat flows from within the Earth- Renewable technology :...

 phenomena known as "mud volcanoes" are often not true mud volcanoes (pelovolcano). See mudpot
A mudpot, mud pool or paint pot is a sort of hot spring or fumarole consisting of a pool of usually bubbling mud. The mud is generally of white to greyish color, but is sometimes stained with reddish or pink spots from iron compounds...

 for further information.

The term mud volcano or mud dome are used to refer to formations created by geo-excreted liquids and gases, although there are several different processes which may cause such activity. Hot water mixes with mud and surface deposits.