Secondary volcanism: gas emission
Volcanic activity, during the quiescent phase, is often followed or accompanied by various phenomena, including the emission of gas and high-temperature water.
Gas emissions are distinguished into:
- fumaroles: emissions of water vapor at high temperature;
- mofettes: emissions of carbon dioxide which, being heavier than air, stagnates on the ground;
- stinkpots: cold emissions of hydrogen sulfide and other sulfur gases (present in Tuscany);
- sulfur vents: hot emissions of sulfurous gaseous compounds (the sulfur vents of Pozzuoli, in Tuscany, are well known in Italy);
- blowholes: emissions of water vapor at high temperature and pressure, in the form of violent jets, which can be exploited as a form of geothermal energy (the boric acid blowholes of Larderello, in Tuscany, are famous in Italy).
