A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
Mauna Loa is one of five volcanoes that form the Island of Hawaii in the U.S. state of Hawaii in the Pacific Ocean. The largest subaerial volcano in both mass and volume, Mauna Loa has historically been considered the largest volcano on Earth, dwarfed only by Tamu Massif. It is an active shield volcano with relatively gentle slopes, with a volume estimated at 18,000 cubic miles (75,000 km3), although its peak is about 125 feet (38 m) lower than that of its neighbor, Mauna Kea. Lava eruptions from Mauna Loa are silica-poor and very fluid, and tend to be non-explosive.
Volcanology is the study of volcanoes, lava, magma and related geological, geophysical and geochemical phenomena (volcanism). The term volcanology is derived from the Latin word vulcan. Vulcan was the ancient Roman god of fire.
A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid lava, which travels farther and forms thinner flows than the more viscous lava erupted from a stratovolcano. Repeated eruptions result in the steady accumulation of broad sheets of lava, building up the shield volcano's distinctive form.
Bradyseism is the gradual uplift or descent 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 βραδύςbradús, meaning "slow", and σεισμόςseismós meaning "movement", and was coined by Arturo Issel in 1883.
Katla is an active volcano in southern Iceland. This particular volcano has been very active historically with at least twenty documented major eruptions since 2920 BCE. In its recent history though, Katla has been less active as the last major eruption occurred in 1918. These eruptions have had a Volcanic Explosivity Index (VEI) of between 4 and 5 on a scale of 0 to 8. In comparison, the Eyjafjallajökull 2010 eruption had a VEI of 4. Larger VEI-5 eruptions are comparable to Mount St. Helens 1980 eruption. Several smaller (minor) eruptions measuring VEI-1 and below have occurred since, with the most recent being in 1999.
A volcano tectonic earthquake or volcano earthquake is caused by the movement of magma beneath the surface of the Earth. The movement results in pressure changes where the rock around the magma has experienced stress. At some point, this stress can cause the rock to break or move. This seismic activity is used by scientists to monitor volcanoes. The earthquakes may also be related to dike intrusion or occur as earthquake swarms.
Cordón del Azufre is a small, inactive complex volcano located in the Central Andes, at the border of Argentina and Chile.
A tiltmeter is a sensitive inclinometer designed to measure very small changes from the vertical level, either on the ground or in structures. Tiltmeters are used extensively for monitoring volcanoes, the response of dams to filling, the small movements of potential landslides, the orientation and volume of hydraulic fractures, and the response of structures to various influences such as loading and foundation settlement. Tiltmeters may be purely mechanical or incorporate vibrating-wire or electrolytic sensors for electronic measurement. A sensitive instrument can detect changes of as little as one arc second.
Aira Caldera is a gigantic volcanic caldera that is located on the southern end of Kyushu, Japan. It is believed to have been formed about 30,000 years ago with a succession of pyroclastic surges. It is currently the place of residence to over 900,000 people. The shores of Aira Caldera are home to rare flora and fauna, including Japanese bay tree and Japanese black pine. The caldera is home to Mount Sakurajima, and the Mount Kirishima group of stratovolcanoes lies to the north of the caldera. The most famous and active of this group is Shinmoedake.
Volcanic gases are gases given off by active volcanoes. These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating from lava, from volcanic craters or vents. Volcanic gases can also be emitted through groundwater heated by volcanic action.
Prediction of volcanic activity, or volcanic eruption forecasting, is an interdisciplinary monitoring and research effort to predict the time and severity of a volcano's eruption. Of particular importance is the prediction of hazardous eruptions that could lead to catastrophic loss of life, property, and disruption of human activities.
A rift zone is a feature of some volcanoes, especially shield volcanoes, in which a set of linear cracks develops in a volcanic edifice, typically forming into two or three well-defined regions along the flanks of the vent. Believed to be primarily caused by internal and gravitational stresses generated by magma emplacement within and across various regions of the volcano, rift zones allow the intrusion of magmatic dykes into the slopes of the volcano itself. The addition of these magmatic materials usually contributes to the further rifting of the slope, in addition to generating fissure eruptions from those dykes that reach the surface. It is the grouping of these fissures, and the dykes that feed them, that serves to delineate where and whether a rift zone is to be defined. The accumulated lava of repeated eruptions from rift zones along with the endogenous growth created by magma intrusions causes these volcanoes to have an elongated shape. Perhaps the best example of this is Mauna Loa, which in Hawaiian means "long mountain", and which features two very well defined rift zones extending tens of kilometers outward from the central vent.
Several types of volcanic eruptions—during which lava, tephra, and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series.
The 2011–2012 El Hierro eruption occurred just off the island of El Hierro, the smallest and farthest south and west of the Canary Islands, in the Atlantic Ocean off the coast of Africa. The island is also the youngest in the volcanic chain. The October 2011 – March 2012 eruption was underwater, with a fissure of vents located approximately 2 kilometres to the south of the fishing village of La Restinga on the southern coast of the island. Increased seismicity in June 2012 to the north-west of the vent did not result in another phase of eruptive activity. Until the 2021 La Palma eruption, which started on 19 September 2021, this was the last volcanic eruption in Spain.
Volcano tectonics is a scientific field that uses the techniques and methods of structural geology, tectonics, and physics to analyse and interpret physical processes and the associated deformation in volcanic areas, at any scale.
Irruputuncu is a volcano in the commune of Pica, Tamarugal Province, Tarapacá Region, Chile, as well as San Pedro de Quemes Municipality, Nor Lípez Province, Potosí Department, Bolivia. The mountain's summit is 5,163 m (16,939 ft) high and has two summit craters—the southernmost 200 m (660 ft)-wide one has active fumaroles. The volcano also features lava flows, block and ash flows and several lava domes. The volcano is part of the Andean Central Volcanic Zone (CVZ).
Gjálp is a hyaloclastite ridge (tindar) in Iceland under the Vatnajökull glacier shield. It originated in an eruption series in 1996 and is probably part of the Grímsvötn volcanic system, though not all the scientists involved are of this opinion.
Ice cauldrons are ice formations within glaciers that cover some subglacial volcanoes. They can have circular to oblong forms. Their surface areas reach from some meters to up to 1 or more kilometers.
Lazufre is a Quaternary volcanic dome in the central Andes, on the border between Chile and Argentina. It is part of the Central Volcanic Zone (CVZ), one of the four distinct volcanic belts of South America. The CVZ includes a number of calderas and supervolcanoes that have emplaced ignimbrites in the region.
