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11 – 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]
The modern monitoring system on Mauna Loa consists not only of its local seismic network but also of a large number of GPS stations, tiltmeters, and strainmeters that have been anchored on the volcano to monitor ground deformation due to swelling of Mauna Loa's subterranean magma chamber, which presents a more complete picture of the events ...
The fractures take the form of a set of concentric cones dipping at a relatively shallow angle into the magma chamber. [3] [13] When the caldera is subsequently emptied by explosive volcanic activity, the roof of the magma chamber collapses as a plug of rock surrounded by a ring fracture. Magma rising into the ring fracture produces a ring dike.
A volcano needs a reservoir of molten magma (e.g. a magma chamber), a conduit to allow magma to rise through the crust, and a vent to allow the magma to escape above the surface as lava. The erupted volcanic material (lava and tephra) that is deposited around the vent is known as a volcanic edifice , typically a volcanic cone or mountain.
Plinian eruption: 1: ash plume; 2: magma conduit; 3: volcanic ash fall; 4: layers of lava and ash; 5: stratum; 6: magma chamber 1822 artist's impression of the eruption of Mount Vesuvius in 79, depicting what the AD 79 eruption may have looked like, by the English geologist George Julius Poulett Scrope.
Sills are fed by dikes, [3] except in unusual locations where they form in nearly vertical beds attached directly to a magma source. The rocks must be brittle and fracture to create the planes along which the magma intrudes the parent rock bodies, whether this occurs along preexisting planes between sedimentary or volcanic beds or weakened planes related to foliation in metamorphic rock.
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]
The earthquake affected both Kanagawa and Shizuoka prefectures, and was measured as an 8.2 on the Richter Scale. The Genroku earthquake had a similar effect on Mt. Fuji as Hoei but with less severity. It clamped the dike of the mountain at 8 km to the surface (where the dacitic magma resides), as well as the basaltic chamber at 20 km deep.