Plate Tectonics
Properties of Magma
Volcanic Eruptions
Volcanic Landforms
Miscellaneous
100
What is a weak spot in the earth's crust where molten material comes to the earth's surface?
A volcano
100
What is a substance that can not be broken down into other substances?
An element.
100
What is the pocket beneath a volcano where magma collects?
The magma chamber.
100
What is the type of volcano that is a wide, gently sloping mountain made of hardened layers of lava and formed by quiet eruptions?
A shield volcano.
100
What is an area where magma melts through the crust in the middle of a plate?
A hot spot.
200
What is the difference between magma and lava?
Magma is the molten mixture of rock-forming substances, gases, and water from deep in the earth's mantle. Lava is magma that reaches the earth's surface.
200
What happens to viscosity as the temperature increases?
As the temperature increases the viscosity decreases.
200
What is the long tube in the volcano that connects the magma chamber to the earth's surface?
The pipe.
200
What do layers of thin, runny lava that flow over a wide area before they cool and harden form?
A lava plateau.
200
What type of eruption can form pahoehoe and aa?
Quiet eruptions.
300
What is the Ring of Fire?
A major volcanic belt formed by the many volcanoes that rim the Pacific Ocean.
300
What is the difference between pahoehoe and aa?
Pahoehoe is hot, fast moving lava. AA is cool, slow moving lava.
300
When does pyroclastic flow occur?
When an explosive eruption hurls ash, cinders, bombs, and gases out of a volcano.
300
What is formed when magma hardens in a volcano's pipe and is later exposed?
Volcanic neck
300
What is a geyser? What is a caldera?
A fountain of water and steam that builds up pressure underground and erupts at regular intervals. A caldera is a huge hole at the top of a volcano formed when the roof of a volcano's magma chamber collapses.
400
How do volcanoes form along the mid-ocean ridges?
Along the rift valley, lava pours out of cracks in the ocean floor, gradually building new mountains.
400
A substance's ability to burn is an example of what? Density, hardness, melting point, and boiling point are all examples of what?
A chemical property A physical property.
400
What happens when a volcano erupts?
The force of the expanding gases pushes magma from the magma chamber through the pipe until it flows or explodes out of the vent.
400
How is a cinder cone volcano formed?
A cinder cone volcano forms when a volcano has explosive eruptions. The lava explodes up into the air and cools forming ash, cinder, and bombs. The ash, cinder and bombs fall and build up around the central vent of the volcano.
400
Explain the difference between an active volcano, a dormant volcano, and a extinct volcano.
An active volcano is a volcano that is erupting or has shown signs of erupting in the near future. A dormant volcano is a volcano that is no longer active, but may be active again in the future. An extinct volcano is a volcano that is unlikely to erupt ever again.
500
How does subduction at converging plate boundaries lead to the formation of volcanoes?
When older denser plate sinks beneath a deep ocean trench into the mantle, some of the rock above the subducting plate melts and forms magma. Since magma is less dense than surrounding rock, it rises to the surface. The magma breaks through the ocean floor creating volcanoes.
500
When magma contains more silica what is the magma like vs. when it contains less silica?
When magma contains more silica it is thicker than when it contains less silica.
500
Explain why ash, cinders, and bombs are only produced in explosive eruptions and not in quiet eruptions.
In order for ash, cinders, and bombs to form lava has to be ejected forcefully from the volcano because it has to be broken into fragments that cool and harden quickly to form pieces of different sizes. Explosive eruptions allow this to occur. Quiet eruptions on the other hand only allows the lava to flow out of the volcano, hardening on top of the previous layer of the volcano.
500
Explain how a composite volcano forms and what layers make up a composite volcano.
A composite volcano is formed when quiet eruptions are alternated with explosive eruptions. This forms alternating layers of lava and ash.
500
What is geothermal energy and how is it used?
Geothermal energy is energy derived from water that has been heated by magma underground. It is used when hot water is piped to buildings as a heat source and steam is piped into turbines to generate electricity.
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