in
Washington, United States ,
Sicily, Italy A
fumarole (or
fumerole; from French
fumerolle, a domed structure with lateral openings, built over a kitchen to permit the escape of smoke) is an opening in a planet's
crust which emits
steam and
gases, but no liquid or solid material. The temperature of the gases leaving the vent ranges from about . The steam forms when groundwater is superheated by hot rock, then flashes (boils due to depressurization) as it approaches the surface. In addition to steam, gases released by fumaroles include
carbon dioxide,
sulfur oxides,
hydrogen sulfide,
hydrogen chloride, and
hydrogen fluoride. These have their origin in magma cooling underground. Not all these gases are present in all fumaroles; for example, fumaroles of
Kilauea in Hawaii, US, contain almost no hydrogen chloride or hydrogen fluoride. A fumarole that emits
sulfurous gases can be referred to as a
solfatara (from old
Italian solfo, "sulfur"). Acid-sulfate
hot springs can be formed by fumaroles when some of the steam condenses at the surface. Rising acidic vapors from below, such as CO2 and H2S, will then dissolve, creating steam-heated low-pH hot springs. Fumaroles are normally associated with the late stages of volcanic activity, although they may also precede volcanic activity A
fumarole field is an area of
thermal springs and gas vents where shallow
magma or hot
igneous rocks release gases or interact with
groundwater. When they occur in freezing environments, fumaroles may cause
fumarolic ice towers. Fumaroles may persist for decades or centuries if located above a persistent heat source; or they may disappear within weeks to months if they occur atop a fresh volcanic deposit that quickly cools. Persistent fumaroles are found at Sulfur Bank on the northern edge of the
Kilauea caldera, but most fumaroles in Hawaii last no more than a few months. some 70,000 years after the most recent eruption. == Economic resources and hazards ==