Central Idea: The Power of Volcanic Eruptions

Questions

1. MultiChoice

   Passage: Molten rock deep beneath Earth's crust contains dissolved gases. As magma rises, decreasing pressure causes gas bubbles to expand rapidly, exploding violently through surface vents. What is the central idea?

2. MultiChoice

   Passage: Pyroclastic flows are superheated avalanches of gas, ash, and rock fragments that race down volcanic slopes at speeds over 100 mph. Their extreme heat and speed destroy everything in their path. What is the central idea?

3. MultiChoice

   Passage: Volcanoes formed by low-viscosity, runny lava create broad, gently sloped mountains called shield volcanoes. Because the fluid lava flows easily across vast distances before hardening, explosions are rare. What is the central idea?

4. MultiChoice

   Passage: High-altitude eruptions hurl tons of microscopic ash into the stratosphere. These abrasive ash clouds stall jet turbine engines and reflect solar radiation, causing temporary global cooling. What is the central idea?

5. MultiChoice

   Passage: Although volcanic eruptions cause destruction, weathered volcanic ash releases rich minerals like nutrients into surrounding soil over time. Consequently, volcanic slopes feature some of the most fertile farmland on Earth. What is the central idea?

6. MultiChoice

   Passage: Encircling the Pacific Ocean basin, the Ring of Fire marks subduction zones where ocean plates slide under continents. This active tectonic belt accounts for over 75 percent of the world's active volcanoes. What is the central idea?

7. MultiChoice

   Passage: When volcanic eruptions melt snowcaps or mix with heavy rainfall, torrential mudflows called lahars form. These fast-moving rivers of wet concrete rush down valleys, burying towns far downstream. What is the central idea?

8. MultiChoice

   Passage: Rare supervolcano eruptions eject thousands of cubic kilometers of material. The resulting massive ash clouds and sulfur gases block sunlight worldwide, causing multi-year volcanic winters and global crop collapses. What is the central idea?

9. MultiChoice

   Passage: Most volcanic activity occurs under ocean waters along mid-ocean ridges. Erupting pillow lava cools rapidly upon contacting seawater, continuously creating new seafloor crust and occasionally building new islands. What is the central idea?

10. MultiChoice

    Passage: By tracking earthquake tremors, monitoring ground swelling with GPS, and analyzing released sulfur gases, volcanologists detect rising magma early. These forecasting tools allow timely evacuations before eruptions occur. What is the central idea?

11. MultiChoice

    Passage: In volcanic regions, magma lies close to Earth's surface, heating underground water reservoirs. Power plants tap this geothermal steam to drive electrical turbines, producing reliable zero-emission energy. What is the central idea?

12. MultiChoice

    Passage: Stratovolcanoes, or composite cones, are built from sequential layers of hardened lava, ash, and pumice. Their steep, symmetrical peaks produce highly explosive eruptions due to thick, viscous magma trapping gases. What is the central idea?