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8th Grade Science Exam Volcanoes Multiple Choice 1. The most important volcanic belt, a narrow zone of active volcanoes that nearly encircles the Pacific basin, is known as the ____. a. Ring of Fire b. Circum-Pacific belt c. Pacific Archipelago d. San Andreas belt 2. According to plate tectonics, earthquakes and volcanoes are far more likely to occur at the edges of ___. a. plates b. tectonics c. caldera d. vent 3. The channel in a volcano through which gases, ash, and molten rock are ejected from the earth’s interior is called the ___. a. lava tunnel b. magma c. caldera d. vent 4. A bowl shaped hollow more than 2 miles wide, formed by a collapse of an underground magma chamber, is called a ____. a. shield b. caldera c. reef d. lagoon 5. An underground tunnel formed when the surface of a large lava flow hardens before the lava beneath is called a ___. a. caldera b. magma chamber c. vent d. lava tunnel 6. Particles or blocks of solid ejecta are collectively referred to as ___. a. calderas b. pyroclasts c. magma d. pahoehoe Matching: Words may be used more than once: Not all will be used!!! a 7. highly explosive volcano l 8. a reservoir of molten rock beneath the surface k 9. the central channel which ejects ash, gases, and rock d 10. Example: mid-atlantic ridge p 11. the thickness of the magma e 12. when plates crash into each other f 13. Example: the san andreas fault g 14. includes water and carbon dioxide h 15. an ejecta of lava i 16. Includes particles or blocks of lava in the air a 17. Volcano of loose material b 18. Pour out lava in gentle eruptions b 19. An example is Mauna Kea in Hawaii a 20. An example is Mt. Saint Helens f 21. Plate boundary when plates slide past each other i 22. Includes volcanic bombs q 23. Most dangerous part of eruption with superheated gases Short Essay a. b. c. d. e. f. g. h. i. j. k. l. m. n. o. p. q. composite volcano shield volcano cinder-cone volcano divergent boundary convergent boundary transform boundary gaseous ejecta liquid ejecta solid ejecta caldera vent magma lava cone crater viscosity fiery blast 24. What is the difference between an active volcano, a dormant volcano, and an extinct volcano? Active: Erupted in the last 50 years. Dormant: Now inactive; “at rest” Extinct: Will not most likely erupt again. 25. What is a person called who studies volcanoes? Volcanologist 26. What two things often precedes a volcanic eruption? 1. Bulging due to build up of magma. 2. Earthquakes.