Portal:Volcanoes
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A volcano is an opening (or rupture) in the Earth's surface or crust, which allows molten rock (lava), ash, and gases to escape from deep below the surface. Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time. Other landforms which are often volcanic in origin include islands, craters, and crater lakes. There are four main types of volcanoes: shield volcanoes, stratovolcanoes, lava domes, and cinder cones.
Volcanoes are generally found where tectonic plates are diverging or converging. A mid-oceanic ridge, like the Mid-Atlantic Ridge, has examples of volcanoes caused by "divergent tectonic plates" pulling apart; the Pacific Ring of Fire has examples of volcanoes caused by "convergent tectonic plates" coming together. By contrast, volcanoes are usually not created where two tectonic plates slide past one another. Volcanoes can be caused by "mantle plumes", so-called "hotspots"; these hotspots can occur far from plate boundaries, such as the Hawaiian Islands. Volcanoes can also form where there is stretching of the Earth's crust and where the crust grows thin (called "non-hotspot intraplate volcanism"). Volcanoes are also found not only on the Earth, but also elsewhere in the Solar System on several planets and moons including Mars, Venus, and Io. (read more...)
Volcanology (also spelled "vulcanology") is the study of volcanoes, lava, magma, and related geological phenomena. The term volcanology is derived from the Latin word Vulcan, the Roman god of fire. Volcanology is a branch of geology. A volcanologist is a person who studies the formation of volcanoes, and their current and historic eruptions. (read more...)
Surtsey (Icelandic: "Surtur's island") is a volcanic island off the southern coast of Iceland. At it is also the southernmost point of Iceland. It was formed in a volcanic eruption which began 130 meters below sea level, and reached the surface on 14 November 1963. The eruption may have started a few days earlier and lasted until 5 June 1967, when the island reached its maximum size of 2.7 km². Since then, wind and wave erosion has seen the island steadily diminish in size: As of 2007, its surface area is 1.4 km² in size.
The new island was named after the fire god Surtr from Norse mythology, and was intensively studied by volcanologists during its creation and, since the end of the eruption, has been of great interest to botanists and biologists as life has gradually colonised the originally barren island. The undersea vents that produced Surtsey are part of the Vestmannaeyjar (Westmann Isles) submarine volcanic system, part of the fissure of the sea floor called the Mid-Atlantic Ridge. Vestmannaeyjar also produced the famous eruption of Eldfell on the island of Heimaey in 1973. The eruption that created Surtsey also created a few other small islands along this volcanic chain, such as Jólnir and other unnamed peaks. Most of these eroded away fairly quickly.
This is a fantastic photo, taken from an aerial view. The Grand Prismatic Spring of Yellowstone National Park shows steam rising from hot and sterile deep azure blue water (owing to the light absorbing overtone of an OH stretch which is shifted to 698 nm by hydrogen bonding [1]) in the center surrounded by huge mats of brilliant orange algae and bacteria. The color of which is due to the ratio of chlorophyll to carotenoid molecules produced by the organisms. During summertime the chlorophyll content of the organisms is low and thus the mats appear orange, red, or yellow. However during the winter, the mats are usually dark green, because sunlight is more scarce and the microbes produce more chlorophyll to compensate, thereby masking the carotenoid colors.
Obsidian is an extrusive igneous rock which is a type of naturally-occurring glass. It is produced when felsic lava erupted from a volcano cools rapidly through the glass transition temperature and freezes without sufficient time for crystal growth. Obsidian is commonly found within the margins of rhyolitic lava flows known as obsidian flows, where cooling of the lava is rapid. Because of the lack of crystal structure, obsidian blade edges can reach almost molecular thinness, leading to its ancient use as projectile points, and its modern use as surgical scalpel blades. (read more...)
- ...that the Tseax Cone in British Columbia was the source for one of Canada's worst known geophysical disasters?
- ...that the Ol Doinyo Lengai stratovolcano (pictured) in Africa's Great Rift Valley is considered the world's strangest volcano because of being the only active volcano in the world with natrocarbonatite lava?
- ...that at 22,615 feet, Ojos del Salado is the highest volcano in the world?
- ...that the 1912 Novarupta eruption of Mount Katmai was the largest of the 20th century?
- ...that a tuya is a type of flat-topped, steep-sided volcano formed when lava erupts through a thick glacier or ice sheet?
WikiProject Volcanoes is the central point of coordination for Wikipedia's coverage of volcanoes, volcanology, igneous petrology, and related subjects. Please feel free to join the project and help!
Volcanology: Volcanologists • Volcanic eruption types • Igneous rocks • Crater lakes • Hotspots • Hydrothermal vents
Volcanoes: Volcanoes by country • Volcanoes by continent • Volcanoes by ocean • Lists of volcanoes • Extraterrestrial volcanoes • Volcanic events and eruptions • Decade Volcanoes • Active volcanoes • Volcanic Seven Summits
The current collaboration of the month is Mount Baker( pictured).
