NATS 1750 Lecture 3: NATS 1750 -Volcanoes.pdf
13 Nov 2014
School
Department
Course
Professor
Document Summary
Shield (or hot spot) All volcanoes have some basic features in common: magma escapes through ssures and cracks in the crust. Usually creates circular conduits or pipes along which the magma ows: lava erupts at the surface through a vent. At their peak many volcanoes also have craters (smaller) or calderas (1 km in diameter or more) All magma also contain a certain percentage of gasses or vola/les (up to 6%) The main gas is water (h20), but nitrogen and carbon dioxide are also present. Presence of these gasses are key, as the pressures the gasses are a signi cant factor in producing explosive erup;ons. The hoyer the magma also the more uid it will be. Shield or hot spot volcanoes. This lava is rela;vely uid so will ow longer distances. Lava tubes are also created, these are tubes where the lave ows under material that has hardened. Another common feature of these volcanoes are large calderas.
