The geothermal phenomena known as "mud volcanoes" are often not true mud volcanoes (pelovolcano). See mudpot for further information.

Mud volcano or mud dome refers to formations created by geo-exuded mud or slurries, water and gases. There are several geological processes that may cause the formation of mud volcanoes. Mud volcanoes are not true igneous volcanoes as they produce no lava. The earth continuously exudes a mud-like substance, which may sometimes be referred to as a "mud volcano". Mud volcanoes may range in size from merely 1 or 2 meters high and 1 or 2 meters wide, to 700 meters high and 10 kilometers wide. Smaller mud exudations are sometimes referred to as mud-pots. The largest (man made) mud volcano is "Lusi" in Java, Indonesia, which is in diameter.