Volcanism
Volcanism comprises the processes by which magma and volcanic gases rise through a planetary crust, erupt at the surface, or solidify underground.
Partial melting: The melting of only some minerals in a rock, producing magma with a different composition from its source. It generates much of the magma that feeds volcanic systems.
Plate tectonics: The theory that Earth's lithosphere is divided into moving plates whose interactions shape the surface. Plate boundaries organize many of Earth's volcanic settings.
Lava flow: A stream or sheet of molten rock that erupts onto a surface and moves before solidifying. Its reach and speed determine how an effusive eruption affects nearby terrain.
Hawaiian volcanism: Volcanic activity in Hawaii, dominated by fluid basaltic lava supplied by a mantle plume. It illustrates persistent, mostly effusive volcanism above a hotspot.
Effusive eruption: An eruption in which lava flows out relatively gently rather than fragmenting explosively. It contrasts with eruptions driven by rapid gas expansion and fragmentation.
Magma: Molten or partly molten rock beneath a planetary surface, often containing crystals and dissolved gases. It is the material transported through the crust during volcanism.
Mantle plume: A rising column of unusually hot mantle material that can cause melting near the surface. Plumes can feed volcanoes far from plate boundaries.
Pyroclastic flow: A fast-moving, ground-hugging mixture of hot gas, ash, and volcanic fragments. It is among the most destructive hazards of explosive volcanism.
Icelandic volcanism: Volcanic activity in Iceland, where a mid-ocean ridge intersects a mantle plume. It combines rifting and plume-related magma supply on exposed land.
Explosive eruption: An eruption that violently fragments magma and ejects gas, ash, and rock. It contrasts with lava-dominated activity that releases pressure more gradually.