SIO15 2022: Topic 9

Volcanoes and Plate Tectonics

handout notes
POSTED: 10 June 2020

supplemental handout: this handout describes details of the geotherm and the two principal mechanism that melt rock inside Earth.

Pinatubo vs. Hawaii

The style of volcanism at Mt. Pinatubo (Philippines) is very different from that of the Hawaiian volcanoes. While Pinatubo's eruptions are typically explosive and very violent, the ones on Hawaiian are "peaceful" and, in fact, a major tourist attraction. Eruptions at Kilauea started with spectacular lava fountains at Pu'u O'o, one of its vents, and is still going on, in 2003 though less dramatically.
This lecture explains why we find volcanoes at some places and not others and why some are violent while others are not.
  • Additional Resources

  • study guide to book chapter 57
    lecture slides #1 (available AFTER the lecture!)
    not-for-credit online quiz for practice testing (do not request edit access!)
  • Six Random Review Questions (not a complete review!)

  • 1) Explosive volcanism is typically associated with shield volcanoes.
    1. true
    2. false
    2) An increasing amount of Silica decreases the viscosity of magma.
    1. true
    2. false
    3) What are rocks called that solidify below the surface?
    1. extrusive
    2. intrusive
    3. effusive
    4. plutonic
    4) Which of the two minerals has the lower melting temperature?
    1. Quartz
    2. Olivine
    5) When magma cools and solidifies, which mineral is the last to crystalize?
    1. Olivine
    2. Quartz
    6) Which melting mechanism is associated with subduction zones?
    1. decompression melting
    2. additions of volatiles

    Answers: 1b; 2b; 3d; 4a; 5b; 6b