Earth Sciences 1022A/B Lecture 4: Earth Science Lecture January 19 2016
7 Aug 2016
School
Department
Course
Professor
Document Summary
Volcano eruptions occur where magma reaches earth"s surface: often from gas buildup in the magma chamber. When the pressure from the buildup gets to be too much, the volcano will erupt. Then the pressure will build up all over again: gas and pyroclastic material are released into the air. The material comes from felsic, viscous material: lava flows will also occur. The composition of the magma determines whether there will be a magma flow or material ejected into the air. Hot, runny mafic lava tends to flow quietly downhill while viscous felsic magma tends to erupt violently with pyroclastic material. Lava types: hot, runny pahoehoe with a surface resembling coils of rope, cooler, blocky aa, pillow lavas form underwater as lava repeatedly breaks through quenched tube ends. Pyroclastic material ranges from dust and ash streamlined bombs and large blocks. Nu e ardentes which are pyroclastic flows of devastating hot glowing clouds of ash and gas.
