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CHSCheyScienceCh6S1
Question | Answer |
---|---|
What's a volcano? | Weak spot in crust where magma comes to surface |
What's magma? Where does it form? | Molten mixture of rock formed in mantle |
What's lava? What does it become when cooled? | Magma that reached surface; becomes rock when cooled |
Is volcanic activity a constructive or destructive force? Why? | Volcanic activity is a constructive force. When lava is cooled, it hardens, adding new material to Earth's surface |
Hot spot? | an area where magma from deep within the mantle melts through the crust. |
Do hot spots result from subduction? | No |
How many volcanoes are currently active on land? | More than 600 |
Where does volcanic activity most often occur at? | divergent plate boundaries; convergent plate boundaries; hot spots far from boundaries of continental/oceanic plates |
Where do volcanic belts form at? | almost always occur along other plate boundaries |
Ring of Fire? | belt of volcanoes that rim Pacific Ocean |
Where do the volcanoes at mid-ocean ridge rise above ocean's surface? | Iceland and Azore Islands |
Why do many volcanoes occur on islands near where two oceanic plates collide? | When two oceanic plates collide, subduction causes oceanic plate to sink, rock heats, becomes magma, seeps through crust, breaks through crust; volcanoes occur |
Island arc? | A string of islands formed by the volcanoes along deep ocean trench |
What are examples of island arcs? | Indonesia, Japan, New Zealand, Carribean Islands, Philippines, Aleutians (tail of Alaska) |
How do volcanoes on land form? | Subduction occurs where edge of continental plate collides with oceanic plate; collision creates volcanic eruptions |
What are examples of volcanoes on land? | Andes Mountains in South America, Pacific Northwest in northwestern United States |
Where do hot spots occur? | Lie in middle of continental or oceanic plate far from plate boundaries |
What are examples of hot spots? | Hawaiian Islands, Yellowstone National Park |
What are the four materials that determine the explosiveness of an explosive volcano? | Gas content, viscosity, temperature, and silica content |