Materials

• Fig. 7.17
• Pencil
• Crayons or colored pencils (red, green, yellow, orange)
• Computer
• Google Earth
• Smithsonian Global Volcanism Program Google Earth layer

Procedure

A. World map of tectonic plates.

1. On the map in Fig. 7.17, put a star on the plate where you are now.
    
2. Locate ridges (the areas of seafloor spreading) and color them green.
    
3. Locate areas of subduction and color them red.
    
4. Locate the areas where composite volcanoes are occurring (in areas where plates are colliding or subducting) and color them yellow.
    
5. Locate volcanoes that are not associated with regions of subduction. Color them purple.
    
6. Answer activity questions 1–5.

B. Google Earth map of volcanoes.
Note: For an introduction to using Google Earth, use this user guide

1. Use Google Earth to examine Earth’s tectonic plates.
   
   1. Open Google Earth software on your computer.
   2. Go to the Smithsonian Volcanism Program website and click “Download Holocene Volcanoes Network Link”
   3. Open the downloaded placemark layer file in Google Earth.
   4. Locate the Places menu in the left-hand sidebar. The newly added placemark layer should appear as “Global Volcanism Program – Holocene Volcanoes” under the “Temporary Places” folder.
   5. Go to the US Geological Survey (USGS) Earthquake Hazards Program website and click "Tectonic Plate Boundaries" to download a map layer.
   6. Open the downloaded USGS map layer in Google Earth. The new map layer should appear in the Places menu under Temporary Places. Both USGS and Smithsonian map layers can be toggled on and off by clicking the check marks next to their names.
       
2. Mount St. Helens, a volcano in the state of Washington, U.S., erupted violently in the past century.
   
   1. Use Google Earth and the USGS Program placemark layer to find Mount St. Helens.
   2. Read the description of this volcano.
   3. Answer activity question 6.
       
3. Investigate island arcs.
   
   1. Use Google Earth to locate the island arcs that make up the Aleutian Islands, the Philippines, Japan, and the Kuril Islands.
   2. Select several different volcanoes and read their descriptions. Note the types of volcanoes that occur within these island arcs.
   3. Answer activity questions 7–9.
       
4. Many of the volcanoes found in the western Pacific ocean basin are associated with subduction zones where one tectonic plate moves underneath another tectonic plate.
   
   1. Use Google Earth to identify different types of volcanoes.
   2. Composite volcanoes (also called stratovolcanoes) are typically found in plate subduction zones. Use Fig. 7.17 to identify the subduction zones around the Pacific ocean basin. Visually search the Google Earth map for volcanoes in this area that occur away from the subduction zones.
   3. Find three distinct volcano groups around the world that are not associated with subduction zones.