Chapter 13

13.1 Volcanoes and Plate Tectonics Magma can form when temperature or pressure changes in mantle rock. Magma also may form when water is added to a hot rock. (Pg 319) Volcanism is any activity that includes the movement of magma onto Earth’s Surface. (Pg 320) Volcanism is common at convergent and divergent boundaries between tectonic plates. (Pg 320- 323) Hot spots are areas of volcanic activity that are located over rising mantle plumes that can exist far from tectonic plate boundaries. (Pg 323) Magma that cools below Earth’s surface forms instructive igneous rock bodies called plutons (Pg 324)

Section 13.1 Major Volcanic Zones Subduction Zones Where one tectonic plate moves under another(convergent). Ocean-Ocean convergence makes Island Arc Volcanoes (Pg 321) Example is Hawaii Continent-Continent convergence Makes mountains and volcanoes Example is the Himalayan Mountains (Mount Everest) Continent- Ocean convergence Example is the Andes Mountains (Chile, South America)

13.2 Volcanic Explosions Lava and Magma can be described as malfic of felsic. Hot, less viscous, mafic lava commonly causes quiet eruptions. Cool, more viscous, felsic lava commonly causes explosive eruptions, especially if it contains trapped gases. (Pg 325-327) Volcanic cones are classified into three categories bases on composition and form. (Pg 328) A caldera forms where a volcanic cone collapses and leaves a large, basin-shaped depression. (Pg 329) Events that might signal a volcanic eruption include changes in earthquake activity, changes in volcano shape, changes in compostion and amount of gases emitted, and changes in patterns of the volcano’s normal activity. (Pg 330)