Volcanism (Chapter 5)

Transcription

1 GEOLOGY 306 Laboratory Instructor: TERRY J. BOROUGHS NAME: Volcanism (Chapter 5) For this assignment, you will require: a calculator, colored pencils, string, protractor, stereoscopes (provided). Objectives for chapter 19: You should be able to explain why some volcanic eruptions are explosive and others are effusive (gently flowing); Summarize the characteristics of shield volcanoes and provide one example of this type of volcano; Describe the formation, size and composition of cinder cones; List the characteristics of composite cone volcanoes and briefly describe how they form; describe two major geological hazards associated with volcanoes. The following questions refer to Chapter 5, 9 th ED.) (Read the chapter 5 (9 th edition) in your manual and then view the pre-lab videos prior to answering the questions from your manual and place your answers in the following spaces provided.) 1. Watch the following pre-lab video for Volcanism: 2. Define Magma: 3. Define Lava: 4. Which Magma has the greatest tendency to form pyroclastic material? 5. Which magma is the most viscous? 6. Which magma is the least viscous? 7. Which magma produces the most gentle eruptions? 8. Which magma produces the most explosive eruptions? 9. What type of magma produce the most fluid lavas? 10. Match the volcanic phenomena with the appropriate picture (1 through 6) Lava fountain B. Fluid lava flow C. Volcanic dome D. Pyroclastic material tephra E. Eruption column F. Silica rich lava flow 1

2 11. List and describe the various types of volcanoes and their corresponding characteristics: 12. Describe the eruption of Mt. St. Helens and the type of eruptive features that were produced as a result. 2

3 13. Use figure 5.2 and match the following: Lava fountain B. Fluid lava flow C. Volcanic dome D. Pyroclastic material (tephra) E. Eruption column F. Silica-rich flow 14. Using Figure 5.3, measure the slope angle for Mauna Loa s flank using a protractor. 15. What are the small hills covered in vegetation in the foreground of the image in figure 5.3? 16. Does the lava flow in figure 5.4 appear to have a high or low viscosity? (Pick one) 17. Does the lava flow in figure 5.4 appear to have a high or low silica content? (Pick one) 18. What would be the compositional name of the lava shown in figure 5.4? 19. Watch the smart figure 5.5 mobile field trip: 3

4 20. Using Figure 5.6, measure the slope angle for SP Crater s flank using a protractor. 21. How does the slope of figure 5.6 compare to the slope of Mauna Loa in figure 5.3? 22. Would you describe the lava that produced the flow in figure 5.7 as fluid or viscous? 23. Using figure 5.8, would you describe this eruption explosive of gentle? 24. Using figure 5.8, what is the name given to the plume rising from the volcano? 25. Name a type of material that would be found in the plume rising from Mt. St. Helens. 26. Using Figure 5.9, measure the slope angle for Mt. Hood s flank using a protractor. 27. Is the slope of Mt. Hood constant or does it change as it gets closer to its peak? 28. Describe the differences in the shape and slope angle between Mt. Hood and Mauna Loa. 29. Define Lahar: 30. Using figure 5.12, which Lahar covered more area? 4

5 31. Using figure 5.12, explain why the Osceola Lahar started out confined to the river valleys, but spread out around Buckley and Enumclaw? 32. Using figures 5.13, 5.14, 5.15, Identify the State furthest East that received volcanic ash from the eruption of Mt. St. Helens 33. Did the magma associated with the eruption of Mt. St. Helens have a high or low silica content? 34. How much ash did Ritzville receive? (figure 5.14) 35. Which direction was the wind blowing during this eruption? 36. Which of the three types of volcanoes pose the greatest threat to property and human life? 37. Which type of volcanoes are Earth s largest? The End! 5