Volcanic gas includes any gas-phase substance that is emitted by volcanic or volcanic-geothermal activity. Volcanic aerosols include liquid or solid particles that are small enough to be suspended in the air, and that are emitted by volcanic or volcanic-geothermal activity (adapted from Baxter and Horwell, 2015, Fischer and Chiodini 2015, and Williams- Jones and Rymer 2015).
" }, "editorialNote": { "en": [ "source:UNDRR HIPS" ] }, "scopeNote": { "en": [ "Volcanic gases can be emitted directly into the atmosphere from magma or by magma interacting with crustal rocks. They can be observed with spectroscopic instruments from ground and space, and their future dispersion can be modelled, allowing forecasts of gas and aerosol concentrations to be made. Volcanic gas composition and concentrations can be modified through interaction with ground or surface waters; gases generated by heating and vaporising groundwater in volcanicgeothermal areas. Volcanic gases can also remain pressurised in the subsurface or within lakes (Oregon State, no date). Volcanic aerosol sizes range from a few nanometres (nm) to several hundred micrometres (μm). Volcanic aerosol refers to particles formed through condensation of volcanic gases, or through reaction of the gases with the atmosphere and sunlight and is thereby distinct from ‘ash’ or ‘tephra’ that is formed through fragmentation of magma or lava. Aerosols can be in liquid or solid form and evolve between these states with time (Oregon State, no date). Volcanic gases and aerosols are emitted by almost any type of volcanic activity: The chemical composition of volcanic gas and aerosol emissions is highly heterogeneous. The composition changes continuously as the emissions drift away from their source and react with the atmosphere and sunlight. Typically, the most abundant volcanic gas is water vapour (80% or more of the gas mass). Other common gases are carbon dioxide (CO2), sulphur dioxide (SO2), hydrogen sulphide (H2S) and hydrogen halides (hydrogen chloride [HCl] and hydrogen fluoride [HF]). Radon and carbon monoxide (CO) are also emitted in trace amounts (Oregon State, no date). Aerosol forms by condensation of volcanic gases, both near-instantaneously after emission, and on the timescale of hours to days. Sulphate, a common aerosol component, forms through conversion of SO2 gas. Aerosol contains a variety of trace components, including elements collectively classified as metal pollutants by environmental and health protection agencies (Oregon State, no date). The abundance of emitted volcanic gases and aerosol varies greatly among eruptions. Recent large eruptions of Holuhraun in Iceland 2014–2015 and Kīlauea Hawaii in 2018, emitted as much SO2 per day as anthropogenic activities in China (50–200 kt/day) over several months (Pfeffer et al., 2018; Kern et al., 2020). A larger-scale emission scenario, which may occur in the coming decades or centuries, includes a ‘Laki-type’ eruption in Iceland which can emit ten times more SO2 than the recent eruptions described above. There are tens, or potentially hundreds, of volcanoes worldwide which emit smaller amounts of SO2 (0.5–5 kt/day) (Carn et al., 2016) but sustain the emissions over years-to-decades (e.g., Mt Etna; Aiuppa et al. 2008). Volcanic gas and aerosol exposure is listed as the cause of 1% of total volcanic hazard fatalities (2283 people; Brown et al., 2017). This estimate includes only fatalities due to extreme direct exposure and does not include premature mortality caused by long-term air and environmental pollution. It has been estimated that 800 million people live within 100 km of a volcano that has erupted in the last 10,000 years (Auker et al., 2013), a range within which they could be exposed to this hazard." ] }, "broader": { "id": "http://connectivity-hub.com/terms/51a19ac2-70fa-43d2-bf50-23fe2b363d0a", "prefLabel": { "en": "Volcanogenic" } }, "inScheme": [ { "id": "http://connectivity-hub.com/terms/", "title": { "en": "Climate Connectivity Taxonomy" } } ], "inSchemeAll": [ { "id": "http://connectivity-hub.com/terms/" } ], "@context": { "@version": 1.1, "id": "@id", "type": "@type", "@vocab": "http://www.w3.org/2004/02/skos/core#", "xsd": "http://www.w3.org/2001/XMLSchema#", "dct": "http://purl.org/dc/terms/", "dc": "http://purl.org/dc/elements/1.1/", "schema": "https://schema.org/", "vann": "http://purl.org/vocab/vann/", "ldp": "http://www.w3.org/ns/ldp#", "owl": "http://www.w3.org/2002/07/owl#", "title": { "@id": "dct:title", "@container": "@language" }, "dc:title": { "@id": "dc:title", "@container": "@language" }, "dc:description": { "@id": "dc:description", "@container": "@language" }, "description": { "@id": "dct:description", "@container": "@language" }, "license": { "@id": "dct:license", "@container": "@language" }, "issued": { "@id": "dct:issued", "@type": "xsd:date" }, "created": { "@id": "dct:created", "@type": "xsd:date" }, "modified": { "@id": "dct:modified", "@type": "xsd:date" }, "creator": "dct:creator", "publisher": "dct:publisher", "preferredNamespacePrefix": "vann:preferredNamespacePrefix", "preferredNamespaceUri": "vann:preferredNamespaceUri", "isBasedOn": "schema:isBasedOn", "source": "dct:source", "prefLabel": { "@container": "@language" }, "altLabel": { "@container": [ "@language", "@set" ] }, "hiddenLabel": { "@container": [ "@language", "@set" ] }, "definition": { "@container": "@language" }, "note": { "@container": [ "@language", "@set" ] }, "changeNote": { "@container": [ "@language", "@set" ] }, "editorialNote": { "@container": [ "@language", "@set" ] }, "historyNote": { "@container": [ "@language", "@set" ] }, "scopeNote": { "@container": [ "@language", "@set" ] }, "notation": { "@container": "@set" }, "example": { "@container": "@language" }, "narrower": { "@container": "@set" }, "related": { "@container": "@set" }, "relatedMatch": { "@container": "@set" }, "narrowerTransitive": { "@container": "@set" }, "broaderTransitive": { "@container": "@set" }, "broadMatch": { "@container": "@set" }, "narrowMatch": { "@container": "@set" }, "closeMatch": { "@container": "@set" }, "exactMatch": { "@container": "@set" }, "hasTopConcept": { "@container": "@set" }, "inScheme": { "@container": "@set" }, "topConceptOf": { "@container": "@set" }, "deprecated": { "@id": "owl:deprecated", "@type": "xsd:boolean" }, "isReplacedBy": { "@id": "dct:isReplacedBy", "@container": "@set" } } }