User:Volcán bobcat/FirstDraft

A volcanologist sampling lava using a rock hammer and a bucket of water.

Pliny the Younger, one of the first volcanologists.

Volcanology (also spelled vulcanology) is the study of volcanoes, lava, and magma and related geological, geophysical and geochemical phenomena that can be grouped under the umbrella term volcanism. The term volcanology is derived from the Latin word vulcan. Vulcan was the ancient Roman god of fire.

A volcanologist is a person who studies the formation of volcanoes, and their current and historic eruptions. Volcanologists frequently visit volcanoes, especially active ones, to observe volcanic eruptions, collect eruptive products including tephra (such as ash or pumice), rock and lava samples.

History of Volcanology

Volcanology has an extensive history. The earliest known recording of a volcanic eruption may be on a wall painting dated to about 7,000 BCE found at the Neolithic site at Çatal Höyük in Anatolia, Turkey. This painting has been interpreted as a depiction of an erupting volcano, with a cluster of houses below shows a twin peaked volcano in eruption, with a town at its base (though archaeologists now question this interpretation). The volcano may be either Hasan Dağ, or its smaller neighbour, Melendiz Dağ.

Religious Explanation

The classical world of Greece and the early Roman Empire explained volcanoes as the work of the gods as science and alchemy had no explanation for their existence. Grecian myths and tales tell of Atlantis, a fabled island that sank into the sea. Plato (428-348 BCE) told of the disappearance of a vast island and its powerful civilization, the Atlanteans, in two of his dialogues, Critias and Timaeus. It is now considered that the island of Thera, now Santorini, in the Aegean Sea, was destroyed by a tremendous series of volcanic explosions around 1620 BCE, with ash falls of up to a foot deep recorded in Turkey. The explosion of Thera sent colossal tsunamis, estimated at 100 feet height, racing across the Aegean, and the southern coast of Crete. Other recordings of the Thera eruption spawned Greek myths, namely the Deucalion, in which Poseidon, god of the sea, took revenge upon Zeus by inundating Attica, Argolis, Salonika, Rhodes and the coast of Lycia (Turkey) to Sicily.

Greeks also considered that Hephaestus, the god of fire, sat below the volcano Etna, forging the weapons of Zeus. His minions, the cyclops with their single staring eye, may be an allegory to the round craters and cones of a volcano. Indeed, the Greek word used to describe volcanoes was etna, or hiera, after Heracles, the son of Zeus. The Roman poet Virgil, in interpreting the Greek mythos, held that the giant Enceladus was buried beneath Etna by the goddess Athena as punishment for rebellion against the gods; the mountain's rumblings were his tormented cries, the flames his breath and the tremors his railing against the bars of his prison. Enceladus' brother Mimas was buried beneath Vesuvius by Hephaestus, and the blood of other defeated giants welled up in the Phlegrean Fields surrounding Vesuvius.

Tribal legends of volcanoes abound from the Pacific Ring of Fire and the Americas, usually invoking the forces of the supernatural or the divine to explain the violent outbursts of volcanoes. Taranaki and Tongariro, according to Māori mythology, were lovers who fell in love with Pihanga, and a spiteful jealous fight ensued. Māori will not to this day live between Tongariro and Taranaki for fear of the dispute flaring up again. Add more examples of american mythologies

Catholic Saints have been attributed to the halt of volcanic activity. The relics of Saint Januarius are credited with the ability to calm Vesuvius. Immediately after the death of Agatha of Sicily, her veil was taken by followers to Mount Etna during a lava flow eruption that threatened the city of Catania in 253 CE. The flow subsequently did not destroy the city, a fact that was attributed to her intercession.

Greco-Roman science

Eruption of Vesuvius in 1822. The eruption of CE 79 would have appeared very similar.

The first attempt at a scientific explanation of volcanoes was undertaken by the Greek philosopher Empedocles (c. 490-430 BCE), who saw the world divided into four elemental forces, of Earth, Air, Fire and Water. Volcanoes, Empedocles maintained, were the manifestation of Elemental Fire. Plato contended that channels of hot and cold waters flow in inexhaustible quantities through subterranean rivers. In the depths of the earth snakes a vast river of fire, the Pyriphlegethon, which feeds all the world's volcanoes. Aristotle considered underground fire as the result of "the...friction of the wind when it plunges into narrow passages."

Wind played a key role in volcano explanations until the 16th century. Lucretius, a Roman philosopher, claimed Etna was completely hollow and the fires of the underground driven by a fierce wind circulating near sea level. Ovid believed that the flame was fed from "fatty foods" and eruptions stopped when the food ran out. Vitruvius contended that sulfur, alum and bitumen fed the deep fires. Observations by Pliny the Elder noted the presence of earthquakes preceded an eruption; he died in the eruption of Vesuvius in 79 CE while investigating it at Stabiae. His nephew, Pliny the Younger gave detailed descriptions of the eruption in which his uncle died, attributing his death to the effects of toxic gases. Such eruptions have been named Plinian in honour of the two authors.

Early Japanese Observations

Japan's first documented historical eruption was from Aso volcano in 553 AD.

Renaissance observations

Pyroclastic flows were described from the Azores in 1580. Georgius Agricola argued the rays of the sun, as later proposed by Descartes had nothing to do with volcanoes. Agricola believed vapor under pressure caused eruptions of 'mointain oil' and basalt.

Jesuit Athanasius Kircher (1602–1680) witnessed eruptions of Mount Etna and Stromboli, then visited the crater of Vesuvius and published his view of an Earth with a central fire connected to numerous others caused by the burning of sulfur, bitumen and coal.

Johannes Kepler considered volcanoes as conduits for the tears and excrement of the Earth, voiding bitumen, tar and sulfur. Descartes, pronouncing that God had created the Earth in an instant, declared he had done so in three layers; the fiery depths, a layer of water, and the air. Volcanoes, he said, were formed where the rays of the sun pierced the earth.

Science wrestled with the ideas of the combustion of pyrite with water, that rock was solidified bitumen, and with notions of rock being formed from water (Neptunism). Of the volcanoes then known, all were near the water, hence the action of the sea upon the land was used to explain volcanism.

Volcano monitoring

Further information: Prediction of volcanic activity

Monitoring active volcanoes and volcanic fields where a new volcano may erupt is a major aspect of volcanology. In areas with significant volcanic risk, volcano monitoring may be primarily performed by a volcano observatory. In 1841, the first volcanological observatory, the Vesuvius Observatory, was founded in the Kingdom of the Two Sicilies.

Volcano seismology

Seismic observations are made using seismographs deployed near volcanic areas, watching out for increased seismicity during volcanic events, in particular looking for long period harmonic tremors, which signal magma movement through volcanic conduits.

Geodetic techniques

Interferogram of Kīlauea showing ground deformation after a 2011 eruption.

Surface deformation monitoring includes the use of geodetic techniques such as leveling, tilt, strain, angle and distance measurements through tiltmeters, total stations and EDMs. This also includes GNSS observations and InSAR. Surface deformation indicates magma upwelling: increased magma supply produces bulges in the volcanic center's surface.

Gas geochemistry

Gas emissions may be monitored with equipment including portable ultra-violet spectrometers (COSPEC, now superseded by the miniDOAS), which analyzes the presence of volcanic gases such as sulfur dioxide; or by infra-red spectroscopy (FTIR). Increased gas emissions, and more particularly changes in gas compositions, may signal an impending volcanic eruption.

Temperature changes are monitored using thermometers and observing changes in thermal properties of volcanic lakes and vents, which may indicate upcoming activity.

Remote sensing

Satellites are widely used to monitor volcanoes, as they allow a large area to be monitored easily. They can measure the spread of an ash plume, such as the one from Eyjafjallajokull's 2010 eruption, as well as SO₂ emissions. InSAR and thermal imaging can monitor large, scarcely populated areas where it would be too expensive to maintain instruments on the ground.

Geophysical techniques

Other geophysical techniques (electrical, gravity and magnetic observations) include monitoring fluctuations and sudden change in resistivity, gravity anomalies or magnetic anomaly patterns that may indicate volcano-induced faulting and magma upwelling.

Stratigraphy and geomorphology

Volcanologist examining tephra horizons in south-central Iceland

Stratigraphic analyses includes analyzing tephra and lava deposits and dating these to give volcano eruption patterns, with estimated cycles of intense activity and size of eruptions. Using tephra deposits to understand the eruptive history of a composite volcano is known as Tephrochronology.

Numerical Methods

Hazard Modeling

In volcanology, computer models are created to simulate eruption processes and forecast potential for loss caused by inundation of volcanic materials. Deterministic models generally focus on a single hazard at a time, such as a single lava flow from a known vent or an ash column from a stratovolcano. Probabilistic models generally focus on a single variety of hazards, such as pyroclastic density currents from many possible locations on one or more volcanoes. These models may employ analytical, cellular automata, finite element, or computational fluid dynamics methods. Hazards that are studied with computer models include ash dispersal, cinder cone development, lava flows, pyroclastic density currents, lahars, and sector collapse.

Hazard models are ideally supported with field data from monitoring efforts. Many models use geochemical data of related events to constrain parameters dealing with magma rheology and fragmentation. Digital elevation models and geomorphologic studies can provide information of characteristic eruption volumes and confining topographic features that effect downward–moving phenomena. Stratigraphy and geochronology can provide insight into recurrence rates of eruptions that inform probabilistic models.

Experimental volcanology

Bowen's reaction series

Volcanic Crisis Management

Volcanic Explosivity Index

The Volcanic Explosivity Index is a tool used by volcanologists to classify eruptions based on their eruptive style and total volcanic output. This classification scheme also shows a relationship between volcanic output, relative occurrence, and destructive power, since larger eruptions tend to happen less frequently and are more catastrophic. The index ranges from 0-8 and is scaled logarithmic from VEI 2 to 8. Volcanic output during an eruption is used in estimating the VEI number regardless of whether the ejecta is lava, ash, bombs, or ignimbrite.

VEI	Ejecta volume	Classification	Description	Frequency	Examples
0	< 10,000 m³	Hawaiian	Effusive	constant	Kīlauea, Piton de la Fournaise, Erebus
1	> 10,000 m³	Hawaiian / Strombolian	Gentle	daily	Nyiragongo (2002), Raoul Island (2006)
2	> 1,000,000 m³	Strombolian / Vulcanian	Explosive	weekly	Unzen (1792), Cumbre Vieja (1949), Galeras (1993), Sinabung (2010)
3	> 10,000,000 m³	Vulcanian / Peléan	Catastrophic	few months	Nevado del Ruiz (1985), Soufrière Hills (1995), Nabro (2011)
4	> 0.1 km³	Peléan / Plinian	Cataclysmic	≥ 1 yr	Mayon (1814), Pelée (1902), Eyjafjallajökull (2010)
5	> 1 km³	Plinian	Paroxysmic	≥ 10 yrs	Vesuvius (79), Fuji (1707), St. Helens (1980)
6	> 10 km³	Plinian / Ultra-Plinian	Colossal	≥ 100 yrs	Veniaminof (c. 1750 BC), Huaynaputina (1600), Krakatoa (1883), Pinatubo (1991)
7	> 100 km³	Ultra-Plinian	Mega-colossal	≥ 1,000 yrs	Mazama (c. 5600 BC), Thera (c. 1620 BC), Samalas (Mount Rinjani) (1257), Tambora (1815)
8	> 1,000 km³	Supervolcanic	Apocalyptic	≥ 10,000 yrs	Yellowstone (640,000 BC), Toba (74,000 BC), Taupo (24,500 BC)

Hazard Maps

Nevado del Ruiz hazard map, showing separate hazard zones for pyroclastics, lavas, and lahars.

Hawaii Island hazard map, showing risk of inundation based on previous lava inundation.

Volcanic hazard maps are created by government agencies to demarcate areas of elevated risk around an active volcano. Hazardous areas may be determined based on historical inundation or on models of volcanic processes. For instance, hazardous locations on the volcanic island of Hawaii might be determined based on the amount of lava inundation in a given area over the last hundred or several hundred years. An alternative strategy might determine risk by modeling possible eruption locations and the advection of volcanic products (e.g. lavas, lahars, ash columns) over the surrounding region.

Unsolved problems in volcanology

Despite massive technological advances in the field of volcanology and improved hazard mitigation strategies in the past twenty years, there are large gaps in the understanding of several physical phenomena related to volcanic activity and evolution. For instance, while simple models of volcano seismology (i.e. earthquakes progress to shallower depths leading to eruption) have proven effective in forecasting eruptions at some volcanoes, eruptions at other volcanoes prove these models are anything but universal. The potential for triggered eruptions from distant earthquakes or other volcanic eruptions are also a matter of current debate.

In long–term volcanic landscape evolution, the genesis of stratovolcanoes is not well constrained. Relatedly, the term ″monogenetic″ to describe volcanoes that ideally erupt once before going extinct is likely too strict for many small, short–lived volcanoes, which may have more than one eruptive phase over the course of over a century (e.g. is Cerro Negro monogenetic or polygenetic?).

Hazard mitigation strategies for ″supervolcanic″ eruptions have yet to be formed, possibly due to the incredible scale of destruction should one occur.

Notable volcanologists

See also: Category:Volcanologists

• Pliny the Elder
• Pliny the Younger
• George-Louis Leclerc, Comte de Buffon (1707–1788)
• James Hutton (1726–1797)
• Déodat Gratet de Dolomieu (1750–1801)
• Norman L. Bowen (1887–1956)
• David A. Johnston, killed during the 1980 eruption of Mount St. Helens
• Harry Glicken, died at Mount Unzen in Japan, 1991
• Katia and Maurice Krafft, died at Mount Unzen in Japan, 1991
• Kiyoo Mogi, developer of the Mogi model of volcano deformation
• Haroun Tazieff, advisor to the French Government and Jacques Cousteau
• George Patrick Leonard Walker, pioneering volcanologist who transformed the subject into a quantitative science
• Haraldur Sigurdsson, Icelandic volcanologist and geochemist
• Chris Newhall, co-creator of the Volcanic Explosivity Index

See also

• International Association of Volcanology and Chemistry of the Earth (IAVCEI)
• GNS Science (formerly the Institute of Geological and Nuclear Sciences) (in New Zealand)
• Igneous rock
• Important publications in volcanology
• Volcano Number
• Global Volcanism Program

External links

• European Volcanological Society
• United States Geologic Survey- Volcanic Hazards Program
• Volcano Live- What is a volcanologist?
• VolcanoWorld- How to become a volcanologist
• World Organization of Volcano Observatories
• Strother, French (April 1915). "Frank A. Perret, Volcanologist". The World's Work: A History of Our Time. XXIX: 688–706. Retrieved 2009-08-04. {{cite journal}}: Cite has empty unknown parameter: |coauthors= (help) and Strother, French (May 1915). "Frank A. Perret, Volcanologist (Concluded)". The World's Work: A History of Our Time. XXX: 85–98. Retrieved 2009-08-04. {{cite journal}}: Cite has empty unknown parameter: |coauthors= (help)

Category:Articles with inconsistent citation formats Category:Earth sciences