GEOL 101 Lecture Notes - Lecture 7: Magma Chamber, Volcanic Plug, Stratovolcano
18 Oct 2016
School
Department
Course
Professor
Document Summary
Volcanism: most volcanoes are located on plate boundaries. Volcanic vents: opening at the summit of a volcano that is connected to the magma chamber. Crater - a summit depression < 1 km (normal opening) Caldera - a summit depression > 1 km (produced by collapse of the top of volcano as. Cinder cone the magma chamber is emptied following a massive eruption: built from ejected fragments, usually of basaltic composition, small size with steep slope angle. Controls on volcanic eruptions: composition and viscosity: silica content. High silica -> higher viscosity lower silica -> lower viscosity: dissolved gases the violence of an eruption is determined by the ability of the gases to escape from the magma as it reached the surface. Gases expand within magma as it nears the surface of the earth because of decreasing pressure. Basaltic volcanism flows easily less explosive: produce shield volcanoes.
