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FINAL 2: Volcanoes
8th Grade Earth Science FINAL 2
| Question | Answer |
|---|---|
| What are the three basic parts of a volcano? | Magma chamber: where magma collects Vent: The opening where magma is forced up and flows onto the Earth’s surface Crater: The steep-walled depression around a volcano’s vent |
| What is the difference between a lava flow and a pyroclastic flow/cloud? | Pyroclastic flow is far more dangerous and is defined as: a giant burning cloud of tephra and gas that flows upward from the crater and/or down the side of the volcano at high speeds. |
| What are the three types of volcanoes? | Shield, Cinder Cone, Composite |
| What is viscosity? | Measure of a liquid’s resistance to flow. Magma’s viscosity is affected by its composition & temperature. |
| How does the temperature affect the viscosity of magma/lava? | The hotter the magma, the lower the viscosity (more liquidy - moves faster.) (Colder = thicker & slower) |
| How does the amount of silica affect the viscosity of magma/lava? | The greater the amount of silica, the higher the viscosity. |
| How does the amount of gas affect the violence of an eruption? | (low gas- non violence, high gas- high violence) The more gas trapped in the magma/lava, the more violent the eruption. |
| What characteristics of lava will cause a violent eruption? | Hotter, lower viscosity, low silica, high gas |
| What are the characteristics of a Shield volcano? | -Broad, slightly domed, with gently sloping sides. -Quiet eruptions of basaltic lava that flow out of the crater forming flat layers w/ a small amount of pyroclastic material. -largest in surface area, not very tall - Mostly associated with hot spots |
| What are the characteristics of a Cinder Cone volcano? | -Steep-sided volcanoes made of ejected lava fragments (tephra). -Loosely packed tephra material. -Shape is affected by the wind - look like ant hills. -Smallest of the volcanoes in size. -Become extinct when it runs out of a magma source. |
| What are the characteristics of a Composite volcano? | -AK.A. Stratovolcano or Strato Cone. -Volcanoes with alternating layers of tephra & lava flows. -Typically erupts andesitic lava and have long dormancy periods punctuated by short violent eruptions. - Mostly associated with convergent plate boundaries. |
| What are the factors that determine a eruption's violence? | magma/lava viscosity & amount of dissolved gas. |
| How does the thickness of a fluid effect it's viscosity? | Thicker fluids have a higher viscosity, while thinner fluids have a lower viscosity. |
Created by:
*BROOKE*
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