A volcano that has erupted within the past few centuries and will likely erupt again.
In the context of igneous materials, a block is a chunk of igneous rock blasted out of a volcano.
A frozen blob of rock formed when magma ejected from a volcano freezes in flight; bombs are typically streamlined.
A large circular depression with steep walls and a fairly flat floor, formed after an eruption as the center of the volcano collapses into the drained magma chamber below.
A subaerial volcano consisting of a cone-shaped pile of tephra whose slope approaches the angle of repose for tephra.
A type of fracturing that yields roughly hexagonal columns of basalt; columnar joints form when a dike, sill, or lava flow cools.
(1) A circular depression at the top of a volcanic mound; (2) a depression formed by the impact of a meteorite.
A volcano that has not erupted for hundreds to thousands of years but does have the potential to erupt again in the future.
Violent volcanic eruption that produces clouds and avalanches of pyroclastic debris.
A volcano that was active in the past but has now shut off entirely and will not erupt in the future.
A line of damage formed in the crystal lattice of a mineral by the impact of an atomic particle ejected during the decay of a radioactive isotope.
Vast sheets of basalt that spread from a volcanic vent over an extensive surface of land; they may form where a rift develops above a continental hot spot, and where lava is particularly hot and has low viscosity.
A thick slurry formed when volcanic ash and debris mix with water, either in rivers or from rain or melting snow and ice on the flank of a volcano.
The empty space left when a lava tunnel drains; this happens when the surface of a lava flow solidifies while the inner part of the flow continues to stream downslope.
Fragmented material that sprayed out of a volcano and landed on the ground or sea floor in solid form.
A fast-moving avalanche that occurs when hot volcanic ash and debris mix with air and flow down the side of a volcano.
A subaerial volcano with a broad, gentle dome, formed either from low-viscosity basaltic lava or from large pyroclastic sheets.
A large, cone-shaped subaerial volcano consisting of alternating layers of lava and tephra.
A pyroclastic igneous rock composed of volcanic ash and fragmented pumice, formed when accumulations of the debris cement together.
Open holes in igneous rock formed by the preservation of bubbles in magma as the magma cools into solid rock.
volcanic debris flow
A mixture of water and clasts of volcanic material that moves down the slope of a volcano.
A layer composed of fragments of igneous material (e.g., tephra, ash, bombs) erupted from volcanoes.