Iodine-131 (usually in the chemical form of iodide) is a component of nuclear fallout, and is particularly dangerous owing to the thyroid gland's propensity to concentrate ingested iodine, where it is kept for periods longer than this isotope's radiological half-life of eight days.
Magma is composed of molten rock and is stored in the Earthâs crust. Lava is magma that reaches the surface of our planet through a volcano vent. Lava flow, Hawai. Courtesy of the U.S. Geological Society.agma is composed of molten rock and is stored in the Earthâs crust. Lava is magma that reaches the surface of our planet through a volcano vent. Lava flow, Hawai. Courtesy of the U.S. Geological Society.
Volcanic processes[edit] Magma from the mantle or lower crust rises through its crust towards the surface. If magma reaches the surface, its behavior depends on the viscosity of the molten constituent rock. Viscous (thick) magma produces volcanoes characterised by explosive eruptions, while non-viscous (runny) magma produce volcanoes characterised by effusive eruptions pouring large amounts of lava onto the surface.