Use the resources listed below to answer the following questions.

• Views of the National Parks – use the information at this link for clarification of volcanic hazards.
• Major Volcanoes of the World (arcgis.com)
• 4 Igneous Processes and Volcanoes – An Introduction to Geology (opengeology.org)

15. Click Major Volcanoes of the World (arcgis.com). At which type of plate boundaries are a majority of composite volcanoes found?
16. Composite volcanoes occur at subduction zones. T/F
17. Do composite volcanoes occur at convergent boundaries where subduction does not occur?
18. Explain your above answer. (Hint: Explore the Major Volcanoes of the World (arcgis.com) and examine other convergent boundaries.)
19. Which parts of the US have composite volcanoes?
20. Is subduction occurring at these locations?
21. Click 4.1 Plate Tectonics and Volcanism – Physical Geology – 2nd Edition (opentextbc.ca) and study Fig. 4.1.1. On which type of a plate do the volcanoes form? Overriding Plate or Downgoing Plate

Click on the textbook link below and scroll down to “4.5.2 Volcano Features and Types.” Study the figure that shows the features of a composite volcano and read the description for composite volcanoes.

• 4 Igneous Processes and Volcanoes – An Introduction to Geology (opengeology.org)
• Volcano Watch — How big is an eruption? (usgs.gov)
• Global Volcanism Program | What volcanoes are the most noteworthy? (si.edu)

22. Why is a composite volcano called by that name?
23. How would you characterize the profile of a composite volcano? Tall and conical or broad dome-like and wide?
24. What do the alternating light and dark bands of rock signify in the composite volcano?
25. What is tephra composed of?
26. Lava flows on composite volcanoes (and elsewhere) are associated with: high silica content (high viscosity) or low silica content (low viscosity).
27. Tephra on composite volcanoes (and elsewhere) are associated with: high silica content (high viscosity) or low silica content (low viscosity).
28. How do alternate layers of lava flows and tephra influence the profile (shape) of composite volcanoes?
29. What scale is used to measure the magnitude and intensity of a volcanic eruption?
30. On this scale, what is considered to be a major eruption?

Let’s examine the recent major eruption history at Mt. St. Helens. Use the resources below to answer the following questions.

• Technical information about the volcano: Mount St. Helens (usgs.gov) & Global Volcanism Program | St. Helens (si.edu)
• Major Volcanoes of the World (arcgis.com)
• NatGeo Plate Tectonics (arcgis.com)
• Watch the USGS video above of the 1980 eruption. Take notes as you watch the video.

31. What are the names of the tectonic plates are involved at this location?
32. What kind of blast occurred during this eruption?
33. What was the area impacted by this blast?
34. What was the reported VEI for the 1980 eruption?
35. Which volcanic hazards were recorded during the 1980 eruption?
36. What were the names of rocks found at this volcano?

Use the resources below to answer the questions.

• Global Volcanism Program | Krakatau (si.edu)
• Major Volcanoes of the World (arcgis.com)
• How Krakatoa made the biggest bang | The Independent | The Independent
• The Eruption of Krakatoa (1883) (uoguelph.ca)
• NatGeo Plate Tectonics (arcgis.com)
• Watch the video above about the recent eruptions at Anak Krakatau

37. What are the names of the tectonic plates are involved at this location?
38. What kind of blast occurred during the 1883 eruption?
39. What was the deadliest hazard that was associated with that eruption?
40. What was the reported VEI for the 1883 eruption?
41. As you can see from the video, (Anak or new or child of) Krakatau is still erupting. Why is this volcano still active?
42. According to the above video, what geologic hazards were caused by the recent eruptions?
43. What types of rocks were reported near this volcano?

Use the resources below to answer the following questions.

• Volcano Watch — Dual volcanic tragedies in the Caribbean led to founding of HVO (usgs.gov)
• Global Volcanism Program | Pelée (si.edu)
• Major Volcanoes of the World (arcgis.com)
• NatGeo Plate Tectonics (arcgis.com)

44. What are the names of the tectonic plates are involved at this location?
45. What was the deadliest hazard that was associated with the 1902 eruption?
46. What was the reported VEI for the 1902 eruption?
47. Explain what made this hazard so deadly.