SIO15 2018: Lecture 8


Volcanoes, Eruption Types and Volcanic Hazards


handout notes

supplemental handout: this handout provides several tables listing significant volcanic eruptions and fatality rates.
LAST MODIFIED:
MODIFIED:
POSTED: 10 October 2018

Arenal, Costa Rica

The 1657m-high (5435ft) Arenal is a moderately silicic (andesitic) stratovolcano and is one of Costa Rica's most active volcanoes. The first known eruption took place only 7000 years ago. Since about 1968, it has been active in a Strombolian eruption type, constantly rumbling, peacefully ejecting small tephra and sometimes lava flows. During its lifetime, Arenal has not always been this peaceful. Activity started 1968 with a big category VEI 3 explosion (photo from the Smithsonian Global Volcanism Program ).
Today, eco-tourists watch Arenal erupting from a safe distance.
This lecture introduces you to some of the most well known volcanoes and the hazard risks that are associated with them.

  • Five Random Review Questions (not a complete review!)

  • 1) Which principal type of eruption is associated with the Plinian type?
    1. particularly benign
    2. particularly violent
    2) What are the principal types of volcanic material?
    1. liquid, solid, gaseous
    2. lava flows, pyroclastic debris, volcanic gases
    3. pahoehoe lava, a'a lava, cinder
    4. lahars, ash flows, lava flows
    3) Which of these volcanic features move fastest down a volcano?
    1. mudflows
    2. lahars
    3. pyroclastic flows
    4. lava flows
    4) Which of these is NOT a volcanic gas?
    1. H2O
    2. CO2
    3. O2
    4. SO2
    5) Of all volcanic hazards, lava flows cause the most fatalities.
    1. true
    2. false


    Answers: 1b; 2b; 3c; 4c; 5b