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Magma chamber. 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 ...
Phreatic eruption at the summit of Mount St. Helens, Washington, in the spring of 1980. A phreatic eruption, also called a phreatic explosion, ultravulcanian eruption or steam-blast eruption, [1] occurs when magma heats ground water or surface water. The extreme temperature of the magma (anywhere from 500 to 1,170 °C (930 to 2,100 °F)) causes ...
Magma chamber) Phreatic eruptions (or steam-blast eruptions) are a type of eruption driven by the expansion of steam. When cold ground or surface water come into contact with hot rock or magma it superheats and explodes, fracturing the surrounding rock [63] and thrusting out a mixture of steam, water, ash, volcanic bombs, and volcanic blocks. [64]
Lassen Peak's northeastern face. Lassen Peak lies near the southern end of the Cascade Volcanic Arc, at the western edge of the Basin and Range Province. Like other Cascade volcanoes, it was fed by magma chambers produced by the subduction of the oceanic Juan de Fuca tectonic plate under the western edge of the continental North American ...
In geology, an igneous intrusion (or intrusive body[1] or simply intrusion[2]) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and compositions, illustrated by examples like the Palisades Sill of New York and New Jersey; [3] the ...
A laccolith is a type of igneous intrusion, formed when magma forces its way upwards through the Earth's crust but cools and solidifies before reaching the surface. Laccoliths are distinguished from other igneous intrusions by their dome-shaped upper surface and level base. They are assumed to be fed by a conduit from below, though this is ...
The formation of these fields may have been influenced by magma ascent along deep fault systems. Trachyandesite is the major eruption product of Huambo. The magmas forming this field formed in deep magma chambers with little modification in shallower magma chambers. Basement lava flows have been dated at 1.05±0.04 mya.
Magma is produced by melting of the mantle or the crust in various tectonic settings, which on Earth include subduction zones, continental rift zones, [5] mid-ocean ridges and hotspots. Mantle and crustal melts migrate upwards through the crust where they are thought to be stored in magma chambers [6] or trans-crustal crystal-rich mush zones. [7]