Knowra Lava dome Lava dome A steep-sided mound formed when viscous lava accumulates around a volcanic vent instead of flowing far away. Its growth can destabilize the dome and produce explosive eruptions or dangerous collapses.
Lava dome growth : The accumulation and deformation of viscous lava around a volcanic vent as a dome enlarges. Extrusion rate, lava viscosity, and cooling determine the dome’s shape and stability.
Mount St. Helens lava dome : A succession of lava domes that grew in Mount St. Helens’ crater after the 1980 eruption. Its repeated growth and collapse provide a closely monitored example of dome activity.
Magma : Molten or partly molten rock beneath Earth’s surface, containing crystals and dissolved gases. Lava dome material begins as magma rising through a volcanic conduit.
Pyroclastic flow : A ground-hugging current of hot gas, ash, and volcanic fragments that moves rapidly down a volcano. Dome collapse is one source of these lethal currents.
Block-and-ash flow : A hot, fast-moving mixture of volcanic blocks, ash, and gas produced by dome collapse or explosive activity. Dome collapse can generate these destructive currents down the volcano’s slopes.
Soufrière Hills volcano : An active volcano on Montserrat whose eruptions since 1995 have built and destroyed lava domes. Its dome collapses produced major pyroclastic flows and reshaped inhabited areas.
Lava : Molten rock erupted onto Earth’s surface, often containing crystals and dissolved gases. A dome is built from lava that has emerged but moves too sluggishly to spread far.
Volcanic ash : Fragments of volcanic rock and glass smaller than two millimeters, produced by explosive eruptions. Explosions involving a dome can disperse ash over broad areas.
Volcanic spine : A steep, solidified mass of viscous magma extruded through a volcanic vent. Some domes develop spines as stiff lava is pushed upward through their cores.
Unzen volcano : A Japanese volcano whose 1991–1995 eruption built a lava dome and generated deadly pyroclastic flows. The dome’s repeated collapses show how hazardous growth can remain over time.
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