Volcano Term Definitions
A bomb-size (> 64 mm) pyroclast that is irregular in form and generally very vesicular. It is usually heavier, darker, and more crystalline than pumice.
The mechanism by which new seafloor crust is created at oceanic ridges and slowly spreads away as plates are separating.
A submarine volcano
An instrument that records seismic waves; that is, vibrations of the earth.
Scientists who study earthquake waves and what they tell us about the inside of the Earth.
An instrument that measures motion of the ground caused by earthquake waves.
Earthquake waves that move up and down as the wave itself moves. For example, to the left.
The motion of surfaces sliding past one another.
A gently sloping volcano in the shape of a flattened dome and built almost exclusively of lava flows.
A trachyandesite composed of olivine and augite phenocrysts in a groundmass of labradorite with alkali feldspar rims, olivine, augite, a small amount of leucite, and some dark-colored glass. Its name is derived from the Shoshone River, Wyoming and given by Iddings in 1895.
A chemical combination of silicon and oxygen
A tabular body of intrusive igneous rock, parallel to the layering of the rocks into which it intrudes.
An opening formed by a collapse in the roof of a lava tube
A type of fumarole, the gases of which are characteristically sulfurous.
A low, steep-sided cone of spatter built up on a fissure or vent. It is usually of basaltic material
A ridge of congealed pyroclastic material (usually basaltic) built up on a fissure or vent.
The density of a mineral divided by the density of water.
Horn-like projections formed upon a lava dome.
A cone shaped deposit of minerals hanging from the roof of a cavern.
The study of rock strata, especially of their distribution, deposition, and age.
A volcano composed of both lava flows and pyroclastic material.
The color of a mineral in the powdered form.
A nearly vertical fault with side-slipping displacement.
A type of volcanic eruption characterized by jetting of clots or fountains of fluid basaltic lava from a central crater
The zone of convergence of two tectonic plates, one of which usually overrides the other.
A ring-shaped cloud of gas and suspended solid debris that moves radially outward at high velocity as a density flow from the base of a vertical eruption column accompanying a volcanic eruption or crater formation.
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