Plate Tectonic - Hazards (1)

  • Plotting volcanoes in western United States.
  • Interpreting the results of data from plotting volcanoes.
  • active
  • dormant
  • extinct
  • volcano

Students examine dangerous volcanoes in the United States.

The 1980 eruption of Mt. St. Helens


Volcanic hazards occur where there are active or dormant volcanoes near inhabited areas, especially urban regions. An "active volcano" is defined as a volcano in an eruptive stage or shows signs of eruption. A dormant volcano is a volcano that has been active in the past, but is presently "sleeping." Dormant volcanoes can erupt again. Dormant volcanoes often have small earthquakes, suggesting magma is moving underneath them. Volcanic areas may have active hot springs, triggered by water heated by the magma. A third type of volcano, an extinct volcano, does not have a magma sources, and will never erupt again.

Your students should realize by now that volcanoes are a hazard. Many volcanoes are located in the western United States, in California, Oregon, and Washington. The most recent eruption in this area was at Mt. St. Helens, in Washington, in 1980. This eruption deposited ash over a wide area stretching as far east as Montana. Landslides caused major damage in the surrounding area, and even prevented river travel on the Columbia River (between Washington and Oregon). Mt. St. Helens continues to erupt lava and the volcano grows.

Mt St. Helens and the other volcanoes in this area are a part of the "Ring of Fire," the geologically active area of volcanoes that encircles the Pacific Ocean. First graders do not have to understand why they occur in this ring. They need to understand that volcanoes can cause damage.

  1. Show the Mt. St. Helens slides within the Volcano Slideshow to your students. Locate Mt. St. Helens on a map of the United States. Most of the other slides in the set show other volcanic hazards. Tell your students that Mt. St. Helens erupted in 1980 and is still active.
  2. Have the students cut out the active and dormant volcano figures on one of the worksheet. Using the list below, review which volcanoes are active and which are dormant. Have the students cut out the volcano figures. You may want to use "cotton balls" for the active volcanoes. Instruct them to paste the pictures on the appropriate volcano. Here are the volcanoes to review:
    Mt. Rainier (dormant)
    Mt. St. Helens (active)
    Mt. Hood (dormant)
    Mt. Baker (dormant)
    Glacier Peak (dormant)
    Mt. Adams (dormant)
    Mt. Shasta (dormant)
    Mt. McLoughlin (dormant)
    Mt. Lassen (dormant)
  3. All of these volcanoes are either active or dormant. Ask the students if this might be a hazardous area. The answer is "yes" because all of these volcanoes have the potential for eruption. Ask the students if people should build big cities near these volcanoes. The answer is "no," because it might endanger people if the volcanoes decide to erupt.

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