GEOG 1350 Lecture Notes - Lecture 3: Novarupta, Cinder Cone, Eve Cone
1 Jun 2016
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Document Summary
Boundary between pacific and north american plate: convergent plate (oceanic plate subduction beneath the continental plate) Ring of fire pacific ocean; most of the world"s volcanoes (& earthquakes) Geological setting for a volcano also relates to earthquake zones. Volcanoes are the surface expressions of the forces that form and mobilize magma. Mid-oceanic ridges and subduction zones allow molten rock to reach surface (magma is molten rock, lava is magma on the earth"s surface) 2/3 of all active volcanoes are located along the ring of fire (subduction zone) Vent in the earth"s surface magma and gases build up and erupt (produces effusive igneous rocks) Magma: described by silica content and amount of dissolved gases; the more silica = the stickier, the stickier = more explosive. Basalt: most common volcanic rock; 45-52% silica; seen in overflow volcanoes (i. e. hawaii) Rhyolite: >68% silica most explosive (i. e. dome volcanoes)
