Volcanology in the context of Isopach map

In volcanology, a lava dome is a circular, mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions on Earth form lava domes. The geochemistry of lava domes can vary from basalt (e.g. Semeru, 1946) to rhyolite (e.g. Chaiten, 2010) although the majority are of intermediate composition (such as Santiaguito, dacite-andesite, present day). The characteristic dome shape is attributed to high viscosity that prevents the lava from flowing very far. This high viscosity can be obtained in two ways: by high levels of silica in the magma, or by degassing of fluid magma. Since viscous basaltic and andesitic domes weather fast and easily break apart by further input of fluid lava, most of the preserved domes have high silica content and consist of rhyolite or dacite.

Existence of lava domes has been suggested for some domed structures on the Moon, Venus, and Mars, e.g. the Martian surface in the western part of Arcadia Planitia and within Terra Sirenum.

Dense-rock equivalent (DRE) is a volcanologic calculation used to estimate volcanic eruption volume. One of the widely accepted measures of the size of a historic or prehistoric eruption is the volume of magma ejected as pumice and volcanic ash, known as tephra during an explosive phase of the eruption, or the volume of lava extruded during an effusive phase of a volcanic eruption. Eruption volumes are commonly expressed in cubic kilometers (km).

Historical and geological estimates of tephra volumes are usually obtained by mapping the distribution and thickness of tephra deposits on the ground after the eruption is over. For historical volcanic explosions, further estimates must be made of tephra deposits that might have changed significantly over time by other geological processes including erosion. Tephra volumes measured in this way must then be corrected for void spaces (vesicles – bubbles within the pumice, empty spaces between individual pieces of pumice or ash) to get an estimate of the original volume of magma erupted. This correction can be made by comparing the bulk density of the tephra deposit with the known density of the original gas-free rock-type that makes up the tephra. The result is referred to as the dense-rock equivalent of the erupted volume.

In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such that expelled lava violently froths into volcanic ash when pressure is suddenly lowered at the vent. Sometimes a lava plug will block the conduit to the summit, and when this occurs, eruptions are more violent. Explosive eruptions can expel as much as 1,000 kg (2,200 lb) per second of rocks, dust, gas and pyroclastic material, averaged over the duration of eruption, that travels at several hundred meters per second as high as 20 km (12 mi) into the atmosphere. This cloud may subsequently collapse, creating a fast-moving pyroclastic flow of hot volcanic matter.

Atmospheric chemistry is a branch of atmospheric science that studies the chemistry of the Earth's atmosphere and that of other planets. This multidisciplinary approach of research draws on environmental chemistry, physics, meteorology, computer modeling, oceanography, geology and volcanology, climatology and other disciplines to understand both natural and human-induced changes in atmospheric composition. Key areas of research include the behavior of trace gasses, the formation of pollutants, and the role of aerosols and greenhouse gasses. Through a combination of observations, laboratory experiments, and computer modeling, atmospheric chemists investigate the causes and consequences of atmospheric changes.

An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysics, oceanography and volcanology are examples of disciplines for which observatories have been constructed.

The term observatoire has been used in French since at least 1976 to denote any institution that compiles and presents data on a particular subject (such as public health observatory) or for a particular geographic area (European Audiovisual Observatory).

In volcanology, a Strombolian eruption is a type of volcanic eruption with relatively mild blasts, typically having a Volcanic Explosivity Index of 1 or 2. Strombolian eruptions consist of ejection of incandescent cinders, lapilli, and volcanic bombs, to altitudes of tens to a few hundreds of metres. The eruptions are small to medium in volume, with sporadic violence. This type of eruption is named for the Italian volcano Stromboli.

The tephra typically glows red when leaving the vent, but its surface cools and assumes a dark to black colour and may significantly solidify before impact. The tephra accumulates in the vicinity of the vent, forming a cinder cone. Cinder is the most common product; the amount of volcanic ash is typically rather minor.

The International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) is a learned society that focuses on research in volcanology, efforts to mitigate volcanic disasters, and research into closely related disciplines, such as igneous geochemistry and petrology, geochronology, volcanogenic mineral deposits, and the physics of the generation and ascent of magmas in the upper mantle and crust. It is one of eight constituent associations of the International Union of Geodesy and Geophysics (IUGG).

IAVCEI is run by an executive committee whose membership changes every four years. The Executive determines policies for the Association, enacting them through a series of commissions and task groups. Bulletin of Volcanology is the journal of IAVCEI.

The Vesuvius Observatory (Italian: Osservatorio Vesuviano) is the surveillance centre for monitoring the three volcanic areas of Campania, Italy: Mount Vesuvius, the Phlegrean Fields and Ischia. Founded in 1841 on the slopes of Mount Vesuvius by Ferdinand II of Bourbon, King of the Two Sicilies, it is the oldest volcanology institute in the world. Its current operative center is based in Naples, hosting an important section of the National Institute of Geophysics and Volcanology.

The Alaska Volcano Observatory (AVO) is a joint program of the United States Geological Survey (USGS), the Geophysical Institute of the University of Alaska Fairbanks (UAFGI), and the State of Alaska Division of Geological and Geophysical Surveys (ADGGS). AVO was formed in 1988, and uses federal, state, and university resources to monitor and study Alaska's volcanology, hazardous volcanoes, to predict and record eruptive activity, and to mitigate volcanic hazards to life and property. The Observatory website allows users to monitor active volcanoes, with seismographs and webcameras that update regularly. AVO monitors more than 20 volcanoes in Cook Inlet, which is close to Alaskan population centers, and the Aleutian Arc due to the hazard that plumes of ash pose to aviation.

AVO operates out of two locations. One is at the U.S. Geological Survey office on the campus of Alaska Pacific University in Anchorage. Other AVO offices are at the Geophysical Institute of the University of Alaska in Fairbanks.

Ejecta (Latin for 'things thrown out'; sing. ejectum) are particles ejected from an area. In volcanology, in particular, the term refers to particles including pyroclastic materials (tephra) that came out of a volcanic explosion and magma eruption volcanic vent, or crater, has traveled through the air or water, and fell back to the ground surface or ocean floor.

Igneous petrology is the study of igneous rocks—those that are formed from magma. As a branch of geology, igneous petrology is closely related to volcanology, tectonophysics, and petrology in general. The modern study of igneous rocks uses a number of techniques, some of them developed in the fields of chemistry, physics, or other earth sciences. Petrography, crystallography, and isotopic studies are common methods used in igneous petrology.

The Japan Meteorological Agency (Japanese: 気象庁, Hepburn: Kishō-chō; JMA) is a division of the Ministry of Land, Infrastructure, Transport and Tourism dedicated to the scientific observation and research of natural phenomena. Headquartered in Minato, Tokyo, the agency collects data on meteorology, hydrology, seismology, volcanology, and other related fields.

The JMA is responsible for collecting and disseminating weather data and forecasts to the public, as well as providing specialized information for aviation and marine sectors. Additionally, the JMA issues warnings for volcanic eruptions and is integral to the nationwide Earthquake Early Warning (EEW) system. As one of the Regional Specialized Meteorological Centers designated by the World Meteorological Organization (WMO), the JMA also forecasts, names, and distributes warnings for tropical cyclones in the Northwestern Pacific region. This includes areas such as the Celebes Sea, the Sulu Sea, the South China Sea, the East China Sea, the Yellow Sea, the Sea of Japan, and the Sea of Okhotsk.

Rogier Diederik Marius Verbeek (7 April 1845, Doorn – 9 April 1926, The Hague) was a Dutch geologist and natural scientist.

His journal Krakatau, which was edited in 1884 and 1885 by order of the Governor-General of the Dutch East Indies, is his most known work. It deals with the eruption of the volcanic island Krakatoa in 1883 and brought volcanology into scientific prominence. Just two years before, Verbeek had done research in the area. Living in Buitenzorg on Java, he was a direct witness to the eruption. In the BBC docudrama Krakatoa: The Last Days, he is the protagonist and was portrayed by Kevin McMonagle.

Phreatic is a term used in hydrology to refer to aquifers, in speleology to refer to cave passages, and in volcanology to refer to a type of volcanic eruption.

In volcanology, a subaerial eruption is any sort of volcanic eruption that occurs on the land surface, or in the open air "under the air". They generally produce pyroclastic flows, lava fountains and lava flows, which are commonly classified in different subaerial eruption types, including Plinian, Peléan and Hawaiian eruptions. Subaerial eruptions contrast with subaqueous, submarine and subglacial eruptions which all originate below forms of a water surface.

This is a partial list of astronomical observatories ordered by name, along with initial dates of operation (where an accurate date is available) and location. The list also includes a final year of operation for many observatories that are no longer in operation. While other sciences, such as volcanology and meteorology, also use facilities called observatories for research and observations, this list is limited to observatories that are used to observe celestial objects.

Astronomical observatories are mainly divided into four categories: space-based, airborne, ground-based, and underground-based.

Patrick Marshall (22 December 1869 – November 1950) was a geologist who lived in New Zealand. He was the first to introduce the terms rodingite and ignimbrite into petrology and mineralogy. Marshall's most significant contribution to science was his work on coastal erosion and volcanology.