GLG 111 Lecture Notes - Lecture 5: Asthenosphere, Lithosphere, Subduction
Document Summary
Nature of volcanic eruption is determined by physical properties of the magma. Creates flat volcanoes and gentle slopes (shield volcanoes) Creates tall volcanoes and steep slopes (composite cones) Lots of pyroclastic material building up vertically. Lava flows can be any composition, but are typically basaltic in composition because basaltic lavas are less viscous than rhyolite lavas. The low viscosity allows the lava to flow easily across the earth"s surface. Gas helps up know when eruptions will occur. As magma moves up there will be more gas escaping. Pyroclastic material hot debris ejected from volcano. Rock, lava, glass fragments, dust, ash, volcanic bombs. The global distribution of volcanoes is not a random phenomenon. We will examine three zones of volcanic activity and their relationship to plate boundaries. Intraplate (within a plate) transform plate boundaries don"t produce volcanoes. Converge or move toward each other, resulting in the destruction of material.
