Characterised by a turbulent output of very hot water + water vapour/steam. Formed when water in the lower crust is heated by the rocks below and it is turned into steam. A build up of pressure is instigated and the water eventually breaks through the surface.
hot springs
hot springs are pools of warm geothermally heated water, laden with minerals
Boiling mud:
hot water mixes with mud and surface deposits
solfatara:
Created when gases, mainlysulphurous,escape on to the surface.
Fumaroles:
superheated water turns to steam as it condenses on the surface.
