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Skills Worksheet Directed Reading A Section: Causes of Volcanic Eruptions coming 1. To help predict eruptions, scientists study from active volcanoes and look for changes in the volcano’s . THE FORMATION OF MAGMA ____ __ 2. The rock of the Earth’s mantle a. flows very quickly. b. has a puttylike consistency. c. is cooler than the Earth’s crust. d. is solid and rock-hard. ____ __ 3. Rock usually melts to form magma a. when there is an increase in pressure. b. when there is a decrease in pressure. c. when there is a decrease in temperature. d. when it is in a volcano. 4. Magma forms in the deeper regions of the Earth’s and the uppermost layers of the . cause 5. Changes in and magma to form. 6. How does magma behave like air bubbles in a jar of honey? c. crater column. a. divergent boundary. b. mantle rock. d. rift zone. 11. Tectonic plates separate at a(n) boundary. on the right more than once. ______24. have not erupted in thousands of years a. active volcano WHERE VOLCANOES FORM ______ 7. About 80% of active b. dormant volcano ______25. have not erupted recently volcanoes on landjoin. formc.where c. extinct volcano collide.plates ______26. are erupting now separate. d. slide past each other. ______27. probably won’t erupt again 8. Tectonic plate boundaries are areas where tectonic plates , , or . ______28. will probably erupt sometime in the future ______29. will probably erupt in the near future Copyright © by Holt, Rinehart and Winston. All rights reserved. Directed Reading A continued 9. Why are the plate boundaries surrounding the Pacific Ocean called the Ring of Fire? WHEN TECTONIC PLATES SEPARATE ______10. A set of rifts between separating plates is called a(n) Section: Causes of Volcanic Eruptions 1. To help predict eruptions, scientists study from active volcanoes and look for changes in the volcano’s coming . Place the following steps of mid-ocean ridge formation in the correct order. Write the appropriate number in each space provided. THE FORMATION OF MAGMA ______ Magma rises surface of thea.surrounding rock. ____ 12. 2. The rock of to thethe Earth’s mantle flows very quickly. __ b. has a puttylike consistency. c. is cooler than the ______13. Mantle material rises to fill the spaces between plates. Earth’s crust. d. is solid and rock-hard. ______14. The magma forms a new crust on the ocean floor. ______15. A rift forms as tectonic plates move apart. ____ 3. Rock usually melts to form magma a. when there is ______ Theincrease mantle in rock melts because the decrease in pressure. __ 16. an pressure. b. whenofthere is a decrease in pressure. c. when there is a decrease in temperature. d. WHEN TECTONIC PLATES COLLIDE when it is in a volcano. ______ 17. Subduction is the movement of one tectonic plate against another. 4. Magma forms in the deeper regions of the Earth’s the movement of one tectonic plate over another. the layers movement of one tectonic plate under another. and the uppermost of the . the movement of one tectonic plate away from cause another. ______18. Convergent boundaries commonly exist where 5. Changes in and magma to form. Howbydoes magma behave tectonic plates move6.side side. like air bubbles oceanic in a jar crust of honey? moves away from continental crust. c. crater under column. continental crust is subducted oceanic a. crust. divergent boundary. b. mantle rock. d. rifteach zone. tectonic plates collide with other. ______19. As the ocean crust sinks deeper into the mantle, 11. Tectonic plates separate at a(n) boundary. it increases in temperature. on the right more than once. it forms a lava fountain. ______24. have not erupted in thousands of years a. active volcano it forms a volcano. its pressure decreases. ______25. have not erupted recently Copyright © by Holt, Rinehart and Winston. All rights reserved. ______26. are erupting now ______27. probably won’t erupt again b. dormant volcano c. extinct volcano Directed Reading A continued 20. The oceanic crust is and than the continental crust. HOT SPOTS ______21. The Hawaiian Islands are located along a tectonic plate boundary. far from any plate boundary. over a lava fountain. on lava plateaus. 22. What are hot spots? 23. Some scientists believe that hot spots form along in the Earth’s crust. PREDICTING VOLCANIC ERUPTIONS Match each volcano type listed on the right with the correct description listed on the left. Write the letters in the space provided. You may use the volcanoes listed Section: Causes of Volcanic Eruptions coming 1. To help predict eruptions, scientists study from active volcanoes and look for changes in the volcano’s . THE FORMATION OF MAGMA ____ __ 2. The rock of the Earth’s mantle a. flows very quickly. b. has a puttylike consistency. c. is cooler than the Earth’s crust. d. is solid and rock-hard. 30. Just before an eruption, the number and intensity of small earthquakes . ____ 3. Rock usually melts to form magma a. when there is 31. Changes in the ratio of sulfur dioxide to carbon dioxide may indicate __ an increase in pressure. b. when there is a decrease in changes in the below. pressure. c. when there is a decrease in temperature. d. when it is in a volcano. 32. Small changes in a volcano’s slope can be detected by a(n) . 4. Magma forms in the deeper regions of the Earth’s and the uppermost layers of the . Copyright © by Holt, Rinehart and Winston. All rights reserved. 5. Changes in and magma to form. 6. How does magma behave cause Directed Reading A continued 33. What are three ways scientists predict volcanic explosions? 34. What might cause a bulge in the slope of a volcano? Copyright © by Holt, Rinehart and Winston. All rights reserved.