Volcanic Ash PDF

*\"Ash cloud\" redirects here. For general topic, see [Ash](https://en.wikipedia.org/wiki/Ash). For other uses, see [Ash (disambiguation)](https://en.wikipedia.org/wiki/Ash_(disambiguation)).* Volcanic ash streams out in an elongated fan shape as it is dispersed into the atmosphere.Ash cloud from t...

*\"Ash cloud\" redirects here. For general topic, see [Ash](https://en.wikipedia.org/wiki/Ash). For other uses, see [Ash (disambiguation)](https://en.wikipedia.org/wiki/Ash_(disambiguation)).* Volcanic ash streams out in an elongated fan shape as it is dispersed into the atmosphere.Ash cloud from the 2008 eruption of [Chaitén volcano](https://en.wikipedia.org/wiki/Chait%C3%A9n_(volcano)), Chile, stretching across [Patagonia](https://en.wikipedia.org/wiki/Patagonia) from the [Pacific](https://en.wikipedia.org/wiki/Pacific) to the [Atlantic Ocean](https://en.wikipedia.org/wiki/Atlantic_Ocean)Ash plume rising from [Eyjafjallajökull](https://en.wikipedia.org/wiki/Eyjafjallaj%C3%B6kull) on April 17, 2010A plane on the ground Description automatically generatedVolcanic ash deposits on a parked [McDonnell Douglas DC-10-30](https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-10) during the 1991 eruption of [Mount Pinatubo](https://en.wikipedia.org/wiki/Mount_Pinatubo). While falling ash behaves in a similar manner to [snow](https://en.wikipedia.org/wiki/Snow), the sheer weight of deposits can cause serious damage to buildings and vehicles. In this case, volcanic ash deposits shifted the airliner\'s center of gravity, leading to it resting on its tail.Ash plume from [Mt Cleveland](https://en.wikipedia.org/wiki/Mount_Cleveland_(Alaska)), a [stratovolcano](https://en.wikipedia.org/wiki/Stratovolcano) in the [Aleutian Islands](https://en.wikipedia.org/wiki/Aleutian_Islands) **Volcanic ash** consists of fragments of rock, [mineral](https://en.wikipedia.org/wiki/Mineral) [crystals](https://en.wikipedia.org/wiki/Crystal), and [volcanic glass](https://en.wikipedia.org/wiki/Volcanic_glass), produced during [volcanic](https://en.wikipedia.org/wiki/Volcano) [eruptions](https://en.wikipedia.org/wiki/Eruptions) and measuring less than 2 mm (0.079 inches) in diameter.[^\[1\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Rose_&_Durant-1) The term volcanic ash is also often loosely used to refer to all [explosive eruption](https://en.wikipedia.org/wiki/Explosive_eruption) products (correctly referred to as [*tephra*](https://en.wikipedia.org/wiki/Tephra)), including particles larger than 2 mm. Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in [magma](https://en.wikipedia.org/wiki/Magma) expand and escape violently into the atmosphere. The force of the gases shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during [phreatomagmatic eruptions](https://en.wikipedia.org/wiki/Phreatomagmatic_eruption), causing the water to explosively flash to steam leading to shattering of magma. Once in the air, ash is transported by wind up to thousands of kilometres away. Due to its wide dispersal, ash can have a number of impacts on society, including animal and human health problems, disruption to aviation, disruption to critical infrastructure (e.g., electric power supply systems, telecommunications, water and waste-water networks, transportation), primary industries (e.g., agriculture), and damage to buildings and other structures. **Formation** \[(https://en.wikipedia.org/w/index.php?title=Volcanic_ash&action=edit&section=1)\] A black object in a stone wall Description automatically generated454 million-year-old volcanic ash between layers of [limestone](https://en.wikipedia.org/wiki/Limestone) in the catacombs of [Peter the Great\'s Naval Fortress](https://en.wikipedia.org/wiki/Peter_the_Great%27s_Naval_Fortress) in [Estonia](https://en.wikipedia.org/wiki/Estonia) near [Laagri](https://en.wikipedia.org/wiki/Laagri). This is a remnant of one of the oldest [large eruptions](https://en.wikipedia.org/wiki/List_of_largest_volcanic_eruptions) preserved. The diameter of the black camera lens cover is 58 mm (2.3 in). Volcanic ash is formed during explosive volcanic eruptions and phreatomagmatic eruptions,[^\[2\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-2) and may also be formed during transport in [pyroclastic density currents](https://en.wikipedia.org/wiki/Pyroclastic_density_current).[^\[3\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-3) Explosive eruptions occur when magma [decompresses](https://en.wikipedia.org/wiki/Decompression_(physics)) as it rises, allowing dissolved [volatiles](https://en.wikipedia.org/wiki/Volatile_(astrogeology)#Igneous_petrology) (dominantly [water](https://en.wikipedia.org/wiki/Water) and [carbon dioxide](https://en.wikipedia.org/wiki/Carbon_dioxide)) to exsolve into gas bubbles.[^\[4\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Wilson_book-4) As more bubbles nucleate a foam is produced, which decreases the [density](https://en.wikipedia.org/wiki/Density) of the magma, accelerating it up the conduit. Fragmentation occurs when bubbles occupy \~70--80 vol% of the erupting mixture.[^\[5\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Cashman_encyclopedia-5) When fragmentation occurs, violently expanding bubbles tear the magma apart into fragments which are ejected into the [atmosphere](https://en.wikipedia.org/wiki/Atmosphere) where they solidify into ash particles. Fragmentation is a very efficient process of ash formation and is capable of generating very fine ash even without the addition of water.[^\[6\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Kueppers_et_al-6) Volcanic ash is also produced during phreatomagmatic eruptions. During these eruptions fragmentation occurs when magma comes into contact with bodies of water (such as the sea, lakes and marshes) groundwater, snow or ice. As the magma, which is significantly hotter than the boiling point of water, comes into contact with water an insulating vapor film forms ([Leidenfrost effect](https://en.wikipedia.org/wiki/Leidenfrost_effect)).[^\[7\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Zimanowski-7) Eventually this vapor film will collapse leading to direct coupling of the cold water and hot magma. This increases the heat transfer which leads to the rapid expansion of water and fragmentation of the magma into small particles which are subsequently ejected from the volcanic vent. Fragmentation causes an increase in contact area between magma and water creating a feedback mechanism,[^\[7\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Zimanowski-7) leading to further fragmentation and production of fine ash particles. Pyroclastic density currents can also produce ash particles. These are typically produced by [lava dome](https://en.wikipedia.org/wiki/Lava_dome) collapse or collapse of the [eruption column](https://en.wikipedia.org/wiki/Eruption_column).[^\[8\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Parfitt_&_Wilson-8) Within pyroclastic density currents particle [abrasion](https://en.wikipedia.org/wiki/Abrasion_(mechanical)) occurs as particles violently collide, resulting in a reduction in grain size and production of fine grained ash particles. In addition, ash can be produced during secondary fragmentation of pumice fragments, due to the conservation of heat within the flow.[^\[9\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Walker-9) These processes produce large quantities of very fine grained ash which is removed from pyroclastic density currents in co-ignimbrite ash plumes. Physical and chemical characteristics of volcanic ash are primarily controlled by the style of volcanic eruption.[^\[10\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-USGS-10) Volcanoes display a range of eruption styles which are controlled by magma chemistry, crystal content, temperature and dissolved gases of the erupting magma and can be classified using the [volcanic explosivity index (VEI)](https://en.wikipedia.org/wiki/Volcanic_explosivity_index). Effusive eruptions (VEI 1) of [basaltic](https://en.wikipedia.org/wiki/Basalt) composition produce \10^9^ m^3^) of ejecta into the atmosphere.[^\[11\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-11) Population growth has caused the progressive encroachment of urban development into higher risk areas, closer to volcanic centres, increasing the human exposure to volcanic ash fall events.[^\[31\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-WilsonEtal2012-31) Direct health effects of volcanic ash on humans are usually short-term and mild for persons in normal health, though prolonged exposure potentially poses some risk of [silicosis](https://en.wikipedia.org/wiki/Silicosis) in unprotected workers.[^\[32\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Horwell_&_Baxter-32) Of greater concern is the impact of volcanic ash on the [infrastructure](https://en.wikipedia.org/wiki/Infrastructure) critical to supporting modern societies, particularly in urban areas, where high population densities create high demand for services.^[\[33\]](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Platt-33)[\[31\]](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-WilsonEtal2012-31)^ Several recent eruptions have illustrated the vulnerability of [urban areas](https://en.wikipedia.org/wiki/Urban_area) that received only a few millimetres or centimetres of volcanic ash.^[\[34\]](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-34)[\[35\]](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-35)[\[36\]](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Wilson_et_al_08-36)[\[37\]](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Wilson_thesis-37)[\[38\]](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Sword-Daniels_thesis-38)^ This has been sufficient to cause disruption of transportation,[^\[39\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-39) [electricity](https://en.wikipedia.org/wiki/Electric_power_distribution),[^\[40\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-40) [water](https://en.wikipedia.org/wiki/Water_supply_network),^[\[41\]](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-41)[\[42\]](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-StewartEtal2006-42)^ [sewage](https://en.wikipedia.org/wiki/Wastewater) and [storm water](https://en.wikipedia.org/wiki/Stormwater) systems.[^\[43\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-FOOTNOTEWilsonStewartSword-DanielsLeonard%224.1._Impacts_on_sewerage_and_stormwater_drainage_networks%22-43) Costs have been incurred from business disruption, replacement of damaged parts and insured losses. Ash fall impacts on critical infrastructure can also cause multiple knock-on effects, which may disrupt many different sectors and services.[^\[44\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-FOOTNOTEWilsonStewartSword-DanielsLeonard%228.2._Case_study_in_infrastructure_interdependency:_Montserrat%22-44) Volcanic ash fall is physically, socially, and economically disruptive.[^\[45\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-45) Volcanic ash can affect both proximal areas and areas many hundreds of kilometres from the source,[^\[46\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-FOOTNOTEWilsonStewartSword-DanielsLeonard%221.4._Distribution%22-46) and causes disruptions and losses in a wide variety of different infrastructure sectors. Impacts are dependent on: ash fall thickness; the grain size and chemistry of the ash; whether the ash is wet or dry; the duration of the ash fall; and any [preparedness](https://en.wikipedia.org/wiki/Emergency_management#Preparedness), [management](https://en.wikipedia.org/wiki/Emergency_management) and [prevention](https://en.wikipedia.org/wiki/Emergency_management#Mitigation_strategy) (mitigation) measures employed to reduce effects from the ash fall. Different sectors of infrastructure and society are affected in different ways and are [vulnerable](https://en.wikipedia.org/wiki/Vulnerability) to a range of impacts or consequences. These are discussed in the following sections.[^\[31\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-WilsonEtal2012-31) **Human and animal health** \[(https://en.wikipedia.org/w/index.php?title=Volcanic_ash&action=edit&section=11)\] Ash particles of less than 10 μm diameter suspended in the air are known to be inhalable, and people exposed to ash falls have experienced respiratory discomfort, breathing difficulty, eye and skin irritation, and nose and throat symptoms.[^\[47\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-ivhhn-47) Most of these effects are short-term and are not considered to pose a significant health risk to those without pre-existing [respiratory conditions](https://en.wikipedia.org/wiki/Respiratory_disease).[^\[32\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Horwell_&_Baxter-32) The health effects of volcanic ash depend on the grain size, mineralogical composition and chemical coatings on the surface of the ash particles.[^\[32\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Horwell_&_Baxter-32) Additional factors related to potential respiratory symptoms are the frequency and duration of exposure, the concentration of ash in the air and the respirable ash fraction; the proportion of ash with less than 10 μm diameter, known as [PM~10~](https://en.wikipedia.org/wiki/Atmospheric_particulate_matter). The social context may also be important. Chronic health effects from volcanic ash fall are possible, as exposure to free crystalline silica is known to cause [silicosis](https://en.wikipedia.org/wiki/Silicosis). Minerals associated with this include [quartz](https://en.wikipedia.org/wiki/Quartz), [cristobalite](https://en.wikipedia.org/wiki/Cristobalite) and [tridymite](https://en.wikipedia.org/wiki/Tridymite), which may all be present in volcanic ash. These minerals are described as 'free' silica as the SiO~2~ is not attached to another element to create a new mineral. However, magmas containing less than 58% SiO~2~ are thought to be unlikely to contain crystalline silica.[^\[32\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Horwell_&_Baxter-32) The exposure levels to free crystalline silica in the ash are commonly used to characterise the risk of silicosis in occupational studies (for people who work in mining, construction and other industries,) because it is classified as a human [carcinogen](https://en.wikipedia.org/wiki/Carcinogen) by the [International Agency for Research on Cancer](https://en.wikipedia.org/wiki/International_Agency_for_Research_on_Cancer). Guideline values have been created for exposure, but with unclear rationale; UK guidelines for particulates in air (PM10) are 50 μg/m^3^ and USA guidelines for exposure to crystalline silica are 50 μg/m^3^.[^\[32\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Horwell_&_Baxter-32) It is thought that the guidelines on exposure levels could be exceeded for short periods of time without significant health effects on the general population.[^\[47\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-ivhhn-47) There have been no documented cases of silicosis developed from exposure to volcanic ash. However, long-term studies necessary to evaluate these effects are lacking.[^\[32\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Horwell_&_Baxter-32) **Ingesting ash** \[(https://en.wikipedia.org/w/index.php?title=Volcanic_ash&action=edit&section=12)\] For surface water sources such as lakes and reservoirs, the volume available for dilution of ionic species leached from ash is generally large. The most abundant components of ash leachates (Ca, Na, Mg, K, Cl, F and SO~4~) occur naturally at significant concentrations in most surface waters and therefore are not affected greatly by inputs from volcanic ashfall, and are also of low concern in drinking water, with the exception of [fluorine](https://en.wikipedia.org/wiki/Fluorine). The elements [iron](https://en.wikipedia.org/wiki/Iron), [manganese](https://en.wikipedia.org/wiki/Manganese) and [aluminium](https://en.wikipedia.org/wiki/Aluminium) are commonly enriched over background levels by volcanic ashfall. These elements may impart a metallic taste to water, and may produce red, brown or black staining of whiteware, but are not considered a health risk. Volcanic ashfalls are not known to have caused problems in water supplies for toxic trace elements such as [mercury](https://en.wikipedia.org/wiki/Mercury_(element)) (Hg) and [lead](https://en.wikipedia.org/wiki/Lead) (Pb) which occur at very low levels in ash leachates.[^\[42\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-StewartEtal2006-42) Ingesting ash may be harmful to [livestock](https://en.wikipedia.org/wiki/Livestock), causing abrasion of the teeth, and in cases of high [fluorine](https://en.wikipedia.org/wiki/Fluorine) content, fluorine poisoning (toxic at levels of \>100 μg/g) for grazing animals.[^\[48\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Cronin_et_al_03-48) It is known from the [1783 eruption of Laki](https://en.wikipedia.org/wiki/Laki#1783_eruption) in Iceland that fluorine poisoning occurred in humans and livestock as a result of the chemistry of the ash and gas, which contained high levels of [hydrogen fluoride](https://en.wikipedia.org/wiki/Hydrogen_fluoride). Following the [1995/96 Mount Ruapehu eruptions](https://en.wikipedia.org/wiki/Mt_Ruapehu#1995-96_eruptions) in New Zealand, two thousand ewes and lambs died after being affected by fluorosis while grazing on land with only 1--3 mm of ash fall.[^\[48\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Cronin_et_al_03-48) Symptoms of [fluorosis](https://en.wikipedia.org/wiki/Dental_fluorosis) among cattle exposed to ash include brown-yellow to green-black mottles in the teeth, and hypersensibility to pressure in the legs and back.[^\[49\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-49) Ash ingestion may also cause gastrointestinal blockages.[^\[37\]^](https://en.wikipedia.org/wiki/Volcanic_ash#cite_note-Wilson_thesis-37) Sheep that ingested ash from the 1991 [Mount Hudson](https://en.wikipedia.org/wiki/Mount_Hudson) volcanic eruption in Chile, suffered from diarrhoea and weakness.