Volcanology

thumb|upright=1.35|Augustine Volcano (Alaska) during its eruptive phase on January 24, 2006

one of the three main rock types; formed through the cooling and solidification of magma or lava

Obsidian ( ) is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. Produced from felsic lava, obsidian is rich in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. It is commonly found within the margins of rhyolitic lava flows known as obsidian flows. These flows have a high content of silica, giving them a high viscosity. The high viscosity inhibits the diffusion of atoms through the lava, which inhibits the first step (nucleation) in the formation of mineral crystals. T

region at edges of Pacific Ocean known for tectonic activity

thumb|280px|A volcanologist sampling lava using a rock hammer and a bucket of water thumb|Eruption of Stromboli (Italy), approximately 100 m (300 ft) vertically. Exposure of several seconds. The dashed trajectories are the result of lava pieces with a bright hot side and a cool dark side rotating in mid-air.

thumb|Kutkhiny Baty, a pumice rock formation outcrop located 4 km from the source of the Ozyornaya (Sea of Okhotsk)|Ozyornaya River (Lake Kurile), near the southern tip of the [[Kamchatka Peninsula, Russia]]

volcanic region

[[File:Supervolcano World Map.png|thumb|upright=1.5|World map of known VEI 7 and VEI 8 volcanoes

Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava (or shallow intrusions) enriched with silica and alkali metals. It is the volcanic equivalent of syenite.

alt=An image of two large cryovolcanoes|thumb|upright=1.5|Leviathan Patera (center) and [[Ruach Planitia (upper left), two large cryovolcanic features on Neptune's moon Triton]]

rock formed from lava erupted from a volcano

underground accumulation of molten rock

relative measure of explosive volcanic eruption size (based on product volume, eruption cloud height, etc.), open-ended with the biggest prehistoric eruptions given magnitude 8

lava containing characteristic pillow-shaped structures due to subaqueous extrusion

material

planar zone of seismicity corresponding with the down-going slab

natural conduits through which lava travels beneath the surface of a lava flow

thumb|Komatiite lava at the type locality in the Komati Valley, Barberton Mountainland, South Africa, showing the distinctive "spinifex texture" formed by dendritic plates of olivine (scale shown by a hammer on the right edge of photo)

A tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or along the direction of foliation in metamorphic rock

medium-grained intrusive rock

Order of crystallization of minerals in magma

range of volcanically active mountains

massive volcanic formation resulting from flood basalt eruptions

right|thumb|250px|Palagonite layers at Moya Beach, Mayotte. Palagonite is an alteration product from the interaction of water with volcanic glass of chemical composition similar to basalt. Palagonite can also result from the interaction between water and basalt melt. The water flashes to steam on contact with the hot lava and the small fragments of lava react with the steam to form the light-colored palagonite tuff cones common in areas of basaltic eruptions in contact with water. An example is found in the pyroclastic cones of the Galapagos Islands. Charles Darwin recognized the origin of the

thumb|Hyaloclastite between Pillow lava|pillows of lava in [[Montana]] thumb|Pahoehoe|Pahoehoe lava enters the Pacific at [[Hawaii Volcanoes National Park, the Big Island of Hawaii]]

a volcanic caldera that has been partially filled by a new central cone

chemical elements or compounds with low boiling points associated with planet’s or moon’s crust or atmosphere

volcanic cone type

process in which only a portion of a solid is melted

type of volcanic eruption

area of the Earth's crust prone to localized volcanic activity

thumb|Mt. St Helens eruption plume on 22 July 1980, showing ejecta in the form of pyroclastic material (ash)

American research program

right|thumb|A sample of rhyodacite from Slovakia Rhyodacite is a volcanic rock intermediate in composition between dacite and rhyolite. It is the extrusive equivalent of those plutonic rocks that are intermediate in composition between monzogranite and granodiorite. Rhyodacites form from rapid cooling of lava relatively rich in silica and low in alkali metal oxides.

volcanic landform which resembles a true volcanic crater, but differs in that it is not an actual vent from which lava has erupted

thumb|220px|right|The "Serapium" or Macellum of Pozzuoli demonstrated the effects of bradyseism. Bradyseism is the gradual uplift (positive bradyseism) or descent (negative bradyseism) of part of the Earth's surface caused by the filling or emptying of an underground magma chamber or hydrothermal activity, particularly in volcanic calderas. It can persist for millennia in between eruptions and each uplift event is normally accompanied by thousands of small to moderate earthquakes. The word derives from the ancient Greek words βραδύς bradús, meaning "slow", and σεισμός seismós meaning "movement

organization

2022 film directed by Sara Dosa

type of outburst flood that occurs when the dam containing a glacial lake fails

Small pieces of solidified lava drops

rock mass from solidified lava flows

low-density flow of fluidized mass of turbulent gas and rock fragments which is ejected during some volcanic eruptions

variety of high-magnesium olivine basalt that is very rich in the mineral olivine

part of a volcano where a set of linear cracks form

type of volcanic glass which resembles the algae

market building of the Roman colony of Puteoli, now the city of Pozzuoli in southern Italy

Vulcania, the "European Park of Volcanism", is an educational French amusement park and museum with a volcano theme. Situated in Saint-Ours-les-Roches, Auvergne, 15 km north-west of Clermont-Ferrand, it was officially inaugurated in 2002.

Gregoryite is an anhydrous carbonate mineral that is rich in potassium and sodium with the chemical formula . It is one of the two main ingredients of natrocarbonatite, found naturally in the lava of Ol Doinyo Lengai volcano of Arusha Region, Tanzania, and the other being nyerereite.

volcanologic calculation

interdisciplinary monitoring and research effort to predict the time and severity of a volcano's eruption

thumb|One of the Houses of the Mayorazgo de Guerrero showing tezontle walls with cantera accents. Tezontle () is a porous, highly oxidized, volcanic rock used extensively in construction in Mexico. It is usually reddish in color due to iron oxide. Tezontle is a well-cemented, agglomeritic and scoriaceous rock.

shield volcano

group of small monogenetic volcanoes

thumb|right|Pozzolana from Mount Vesuvius volcano, Italy Pozzolana or pozzuolana ( , ), also known as pozzolanic ash (), is a natural siliceous or siliceous-aluminous material that reacts with calcium hydroxide in the presence of water at room temperature (cf. pozzolanic reaction). In this reaction insoluble calcium silicate hydrate and calcium aluminate hydrate compounds are formed possessing cementitious properties. The designation pozzolana is derived from one of the primary deposits of volcanic ash used by the Romans in Italy, at Pozzuoli. The modern definition of pozzolana encompasses any

Japanese museum near Mount Aso

floating mass of pumice in the ocean

expert group providing information on atmospheric volcanic ash clouds hazardous for airplanes

thumb|right|A tiltmeter on Mauna Loa, used to predict eruptions by measuring very small changes in the profile of the mountain.

thumb|upright=1.35|The Espinaso Formation includes a wide variety of volcaniclastic materials. Volcaniclastics are geologic materials composed of broken fragments (clasts) of volcanic rock. These encompass all clastic volcanic materials, regardless of what process fragmented the rock, how it was subsequently transported, what environment it was deposited in, or whether nonvolcanic material is mingled with the volcanic clasts. The United States Geological Survey defines volcaniclastics somewhat more narrowly, to include only rock composed of volcanic rock fragments that have been transported so