GEOL105 Lecture Notes - Lecture 4: Subduction, Plinian Eruption, Strombolian Eruption
Document Summary
Crust forms quickly, interior cools much more slowly (crust insulates the inside) The cooled and solidified rock is also referred to as lava. Very hot: about 1000 to 1300 degrees celsius. Very fluid: thin flows can travel long distances and cover large areas. Not dangerous to people unless directly in it"s path. Higher viscosity- thicker flows, don"t travel as far. Coolest lavas: 650 800 degrees celsius. Magma that is thrown through the air: can be mixed with volcanic gases. Very small pumice fragments, glass shards or rock fragments. As cloud moves downwind ash falls out, heaviest particles first, closest to vent. Larger eruptions produce more ash and distribute it farther. Ash and hot gas (850-1200 degrees c) glowing down from vent at up to. 200km/hr (125 mph)- pushed by mostly just gravity. Flows can cross over ridges and across bodies of water. Some flows have traveled more than 100 km (63 miles) Asphyxiate and parboil people (kills people almost instantly)
