7.8: Geological Activity and Volcanoes- Challenge 1
- Page ID
- 5432
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- 1. A volcano on the Hawai'i hotspot is ___; a volcano that has just moved off the hotspot is ___; a volcano that is far from the hotspot is ___.
- active; dormant; extinct
- 2. Volcanoes are located around ___ and ___ plate boundaries.
- convergent; divergent
- 3. Mantle rock melts to form ___ if temperature rises, pressure decreases, or water mixes with the mantle.
- magma
- 4. Lava erupts through long cracks in the ground called ___.
- fissures
- 5. ___ are a chain of volcanoes in the Pacific Northwest of North America that formed on a convergent plate boundary.
- The Cascades
- 6. Which of the following is/are example(s) of volcanic arcs: the Himalayas, Mount Gahinga, or the Cascades?
- The Cascades
- 7. Hotspot volcanoes form when ___.
- a plate moves over a mantle plume
- 8. A hotspot beneath the Big Island of Hawai'i is currently covered by the ___ volcano.
- Kilauea
- 9. Eruptions of hotspots beneath continents are extremely explosive, because ___.
- a mantle plume must be massive to penetrate continental crust
- 10. Magma viscosity is related to magma composition: the higher the silica content, the ___ the viscosity.
- higher
- 11. ___ is a fluid's resistance to flow.
- viscosity
- 12. ___ lava is low in silica, less viscous, and erupts effusively.
- Mafic
- 13. A ___ is a volcanic mudflow made of ash and water, while a ___ is made of hot fragments of rock and ash.
- lahar; pyroclastic flow
- 14. Before an explosive eruption, ___ pressure builds until it is released violently.
- gas
- 15. Mt. Shasta, an active volcano, is located in ___.
- California