big atomic bomb. Penn State students, being naturally even-tempered, don’t kick hard enough to actually explode Pepsi machines. And Penn State basements are not deep enough to account for the deeper earthquakes. Points Earned: 1/1 Correct Answer: B Your Response: B 13. Some eruptions come out of volcanoes really rapidly and shoot really high because: A. As the melt nears the surface in subduction-zone volcanoes, the higher stresses from the nearby subduction zones squeeze the melt out faster. B. The suction from the pull of spreading ridges makes the melt come out really rapidly. C. Hot spots shove the melt out faster. D. Giant marmots named George suck the melt out. E. Dropping pressure as the melt rises allows volatiles including water vapor and carbon dioxide to make bubbles that lower the density and make the melt rise even faster. Just as uncapping a shaken soda bottle or champagne bottle allows a foaming “eruption”, it is the bubbles forming in rising lava that make it go fast. Although stomping on a fast-food ketchup package can cause a squeeze-driven “eruption”, real volcanoes are not primarily squeeze-driven, mostly because it takes a pretty big “stomp” to drive one, and the Earth doesn’t stomp hard enough (even in earthquakes!). (The squeezes that fold and break rocks to make mountains are actually rather slow.) Hot-spot volcanoes tend to erupt quietly, slowly, and not very high into the air. Spreading ridges don’t pull on their surroundings; the ridges actually push a little. And George surely can’t do that, even if he is cute. Points Earned: 1/1 Correct Answer: E Your Response: E
14. Look at the picture above. What type of volcano is this? A. A subduction-zone-type, steep andesitic stratovolcano B. A head-of-hot-spot, mushroom-cloud-type plateau basalt C. The mound made when a giant marmot named George dug his hole D. A hot-spot-type, basaltic shield volcano E. A small, loose, thrown-rocks-type cinder-cone volcano This is Lassen Peak in Lassen Volcanic National Park, northern California. Lassen erupted between 1914 and 1921, near the south end of the Cascades chain of subduction-zone volcanoes, and was made a national park in 1916. Hot-spot volcanoes aren’t as steep, plateau basalts cover state-sized areas with very flat-lying flows, cinder-cone volcanoes are much smaller, and George’s piles are smaller yet. Points Earned: 1/1 Correct Answer: A Your Response: A 15. the island of Hawaii eventually will: A. Blow up as powerfully as the main eruptions of Yellowstone, 1000 times bigger than Mt. St. Helens. B. Rise above sea level as they cool and sink, and are eroded. C. Last forever while nothing happens to them except for development of a protective layer of condominiums. D. Blow up as powerfully as the main 1980 eruption of Mt. St. Helens. E. Drift off the hot spot and cease to erupt, while a new volcano grows to their southeast.
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