Volcanic gas
In explosive volcanic eruptions, the sudden release of gases from magma may cause rapid movements of the molten rock.As magmatic gas travelling upward encounters meteoric water in an aquifer, steam is produced.Cooling can cause phase separation and mineral deposition, accompanied by a shift toward more reducing conditions.At the surface expression of such hydrothermal systems, low-temperature volcanic gases (<400 °C) are either emanating as steam-gas mixtures or in dissolved form in hot springs.At the ocean floor, such hot supersaturated hydrothermal fluids form gigantic chimney structures called black smokers, at the point of emission into the cold seawater.Hot springs on volcanoes often show a measurable amount of magmatic gas in dissolved form.Present day global emissions of volcanic gases to the atmosphere can be classified as eruptive or non-eruptive.Accordingly, a large part of hazard monitoring of volcanoes involves regular measurement of gaseous emissions.For example, an increase in the CO2 content of gases at Stromboli has been ascribed to injection of fresh volatile-rich magma at depth within the system.Volcanic gas sensing can be: Sulphur dioxide (SO2) absorbs strongly in the ultraviolet wavelengths and has low background concentrations in the atmosphere.Analytical techniques for gas samples comprise gas chromatography with thermal conductivity detection (TCD), flame ionization detection (FID) and mass spectrometry (GC-MS) for gases, and various wet chemical techniques for dissolved species (e.g., acidimetric titration for dissolved CO2, and ion chromatography for sulfate, chloride, fluoride).Certain constituents of volcanic gases may show very early signs of changing conditions at depth, making them a powerful tool to predict imminent unrest.The Deep Earth Carbon Degassing Project is employing Multi-GAS remote sensing to monitor 9 volcanoes on a continuous basis.
Pyroclastic flowtephraAugustine VolcanoAlaskavolcanoesvesiclesvolcanic rocksgroundwater heated by volcanic actionEarth's mantleEarth's crustgroundwaterEarth's atmospherecarbon dioxide emissioncraterVillarrica, Chilewater vaporcarbon dioxidesulfursulfur dioxidehydrogen sulfidenitrogenheliummethanecarbon monoxidehydrogencompoundsoxygenhydrogen chloridehydrogen fluoridehydrogen bromidesulfur hexafluoridecarbonyl sulfideorganic compoundsmercuryhalocarbonshalogenradicalsconvergent platechlorinehot spotsdivergent platesubduction zoneshot spotsuper-saturatedStromboliSanta Maria volcanoGuatemalaSoufrière HillsMontserratviscosityequilibriumvolcanic eruptionsmeteoric wateraquifercountry rockionic strengthphase separationmineralhydrothermalhot springsblack smokersseawateradvectionrare mineralsfumarolessolfatarasmofettesgreenhouse gasteragramsgigatons1991 eruption of Mount Pinatubo2010 eruptions of Eyjafjallajökullfossil fuelscementScipione Breislakinfrared-spectroscopicspectroscopyDifferential Optical Absorption SpectroscopyFourier Transform Infrared SpectroscopyMulti-Component Gas Analyzer SystemcausticRobert W. Bunsenchromatographythermal conductivityflame ionization detectionmass spectrometrytitrationion chromatographysulfatechloridefluorideisotopicPrediction of volcanic activityseismicitydeformationvolcano observatoryremote sensingDeep Earth Carbon Degassing ProjectcorrosionasphyxiationaerosolsHawaiiKilaueaLava fountainsHoluhraunIcelandlava fieldmudpotsKraflaYellowstone National ParkAmygduleEruption columnFumaroleGas lawsGeyserLake NyosMofetteSolfataraVolatility (chemistry)Volatile (astrogeology)BibcodeCalderaCinder coneComplex volcanoCryovolcanoCryptovolcanic structure