Plate Tectonic - Volcanoes (6)
Post Lab 

   
OBJECTIVES:
  • Researching where volcanoes occur around the world.
  • Comparing the different areas where volcanoes occur.
VOCABULARY:
  • converging
  • diverging
  • plate tectonics
MATERIALS:
  • worksheet
  • relief map of the world
  • Internet
  • other publications that list volcanic eruptions

Students research active volcanoes.

BACKGROUND:

Volcanic eruptions occur continuously around the world. They have also occurred throughout geologic time. The Earth has been restless since it was created 4.5 billion years ago, so we can assume that volcanoes were a basic building unit of the original Earth. Volcanoes were and are important to the development of the Earth. Lava produced the crust when the Earth was forming. Volcanoes also produced much of the Earth’s water. Hydrogen and oxygen chemically combined inside the Earth, and the resulting water molecules "outgassed" from volcanoes as steam into the atmosphere.

The Post Lab is a research activity. The students will find recent eruptions listed in reference material or on the Internet. They will then plot their findings on a classroom map. The pattern that they will find is that most volcanoes are created at diverging and converging plate boundaries.

As described in the Pre Lab background, most volcanoes occur at convergent or divergent plate boundaries, and at a few intraplate settings. Only convergent boundaries where subduction (one plate sinks beneath another, creating much magma) produce volcanoes. Convergent boundaries where collisions take place produce little magma. Divergent plate boundaries probably have the most volcanic activity in the world, but most of these are located within the oceans, and are unknown. Intraplate volcanoes are caused by hotspots, and can occur anywhere.

There are many ways to format this assignment. Enclosed is an example of how the students can collect the data from their reference material. Alternatively, you may want the students just to find locations on a map, and not to copy all the information down.

PROCEDURE:
  1. Review the settings of volcanoes with the class.
      
  2. Give the class their assignment. Have each group of students find 3-5 volcanoes in the library or on the Internet. You may want to assign particular geographic areas to different students or student groups. If you assign Internet research, here are a few sites to start with or have students conduct their own search.
      
    http://volcano.und.nodak.edu/vwdocs/current_volcs/current.html/ 
    Information on currently erupting volcanoes around the world, with links to each site.
      
    http://www.geo.mtu.edu/volcanoes/ 
    Michigan Technological University - volcano sites from around the world.

    http://www.usgs.gov/ 
    The US Geological Survey website. Excellent information on US volcanoes, as well as plate tectonics and geologic hazards.
      
  3. Have each student group share their information with the rest of the class. Have the students plot their findings on the classroom map. If you are using the relief map, make sure that the students notice that volcanoes are usually on mountainous areas, but that not all mountains are volcanoes.

    The students will notice that volcanoes are more abundant in the circum-Pacific region and the Mid-Atlantic Ridge area. These are primarily convergent and divergent settings, respectively. However your students will have also have plots of areas like Hawaii, that are intraplate volcanoes. Explain that these do not fit the plate tectonic model for the formation of volcanoes, but are still fairly well understood by geologists.

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