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A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. [1] Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and periodic intervals of explosive eruptions and effusive eruptions, although some have collapsed summit ...
Magma composition H 2 O concentration wt % MORB 0.1 – 0.2 Island tholeiite 0.3 – 0.6 Alkali basalts 0.8 – 1.5 Volcanic arc basalts 2–4 Basanites and nephelinites: 1.5–2 Island arc andesites and dacites 1–3 Continental margin andesites and dacites 2–5 Rhyolites up to 7
An anomalously old potassium–argon date of 5.9 ± 1.1 million years has been obtained from Kitsu Member alkali basalt. [46] Potassium–argon dates more in line with the volcanic stratigraphy include 3.1 ± 0.1 million years and 3.0 ± 0.1 million years from comendite and 3.4 ± 0.1 million years and 2.9 ± 0.1 million years from comenditic ...
Before the eruption, Aniakchak was a 2,300 meters (7,500 ft) high [117] deeply eroded stratovolcano [118] with two separate magma bodies, one andesitic and the other rhyodacitic, under Aniakchak at least 4.1–5.5 kilometers (2.5–3.4 mi) in depth. [63] These two magma bodies had evolved independently in the time before the eruption. [119]
In essence, fractional crystallization is the removal of early formed crystals from an originally homogeneous magma (for example, by gravity settling) so that these crystals are prevented from further reaction with the residual melt. [3] The composition of the remaining melt becomes relatively depleted in some components and enriched in others ...
A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it upwards. [1] If the magma finds a path to the surface, then the result will be a volcanic eruption ...
Pinatubo in the Philippines on 15 June 1991, which produced 5 km 3 (1 cu mi) of dacitic magma, a 40 km (25 mi) high eruption column, and released 17 megatons of sulfur dioxide. [ 46 ] Kelud , Indonesia erupted in 2014 and ejected around 120,000,000 to 160,000,000 cubic metres (4.2 × 10 9 to 5.7 × 10 9 cu ft) volcanic ashes which caused ...
VEI. 5. Impact. Buried the Roman settlements of Pompeii, Herculaneum, Oplontis, and Stabiae. Deaths. 1,500–3,500, possibly up to 16,000 [1][note 1] Of the many eruptions of Mount Vesuvius, a major stratovolcano in Southern Italy, the best-known is its eruption in 79 AD, [2][3] which was one of the deadliest in history.