Vocabulary
Define volcano
An opening in Earth's crust that allows magma, volcanic ash, and gases to escape from below the surface.
It escapes a volcano during an eruption (one of three)
Magma, volcanic ash, or gases
Does magma get released from a volcano during an eruption
Define lava flow
A lava flow is stream of molten rock that escapes onto the surface from an erupting volcano vent.
Melted rock on Earth's surface
Lava
When a volcano collapses, a hole called a vent is left behind
False (Caldera is left behind)
Define volcanic neck
A volcanic neck is a landform created when magma cools and hardens inside the vent of a volcano.
Wide volcano with gradual slope
Shield Volcano
If a volcano is thick and sticky, it has high silica content
True
Why are some eruptions gentle and others explosive?
High viscosity and gas content can cause explosive eruptions and lower viscosity/gas content are gentler eruptions. Thick magma traps gas, and this gas rises quickly during an eruption, causing explosions.
How is pahoehoe formed?
The cooling of low viscosity, low gas content, magma.
Define batholith
A large area of intrusive igneous rock that forms when magma cools under the surface.
Underground storage area of magma
Magma chamber
A cinder cone volcano has low silica content
False (High silica content)
Can a volcano erupt without lava?
Yes, it can release ash, or gas.
No, it mostly depends on pressure buildup of gases before an eruption.
Define a dike and a sill
A dike cuts across rock vertically while a sill cuts across rock horizontally, parallel to the rock layers.
Thickness/stickiness of magma
Viscosity
A dormant volcano is permanently dead
If a volcano hasn’t erupted in over 10,000 years, is it guaranteed extinct? Why or why not.
No. It could still be dormant, as volcanoes can take a long time in between eruptions.
Would a volcano under the ocean still be considered a volcano?
Yes, because it still erupts magma/lava from Earth’s crust, just underwater.