Molten rock and gas leave the volcano through an opening called a ____.
What is vent
100
What makes an eruptions quiet or explosive?
What is it depends on the amount of silica and whether the magma is thin and runny or thick and sticky.
100
Geologists use the terms ______, _______, or _______ to describe a volcano's stage of activity.
What is active, dormant, or extinct
100
At what point does magma become lava?
What is at Earth's surface
200
A ______ is a bowl-shaped area that may form at the top of a volcano around the central vent.
What is crater
200
______ is a material found in magma that forms from the elements oxygen and silicon.
What is silica
200
Describe an active volcano.
What is Active, or live, volcanoes are ones that are erupting or has shown signs that it may erupt in the near future.
200
How might a volcano be hazardous for plants and animals that live nearby?
What is Lava can kill tree and possible small animals such as squirrels, rats, insects, etc.
300
All volcanoes have a pocket of magma beneath the surface. Magma is collected in the _____ _______.
What is magma chamber
300
What are the 2 types of eruptions?
What is quiet and explosive
300
Describe a dormant volcano.
What is Dormant, or sleeping, volcanoes are expected to awaken in the future and become active.
300
What type of rock forms from thin and runny, fast-moving lava?
What is Pahoehoe
400
A ____ ____ is the spread of lava as it pours out of a vent.
What is lava flow
400
A ___________ ____ is the mixture of hot gases, ash, cinders, and bombs that flow down the sides of a volcano when it erupts explosively.
What is pyroclastic flow
400
Describe an extinct volcano.
What is Extinct, or dead, volcanoes are highly unlikely to erupt ever again.
400
As magma rises to the surface during an eruption, pressure on the magma decreases, allowing gas bubbles to _______.
What is rise
500
Magma moves upward through a ____, a long tube that extends from Earth's crust up through the top of a volcano, connecting the magma chamber to the Earth's surface.
What is pipe
500
Describe and explain the 2 types of lava that quiet eruptions make?
What is Pahoehoe forms fast-forming, hot lava that is thin and runny. It looks like a solid mass of ropelike coils. Aa forms from lava that is cooler and thicker. It looks like jagged lava chunks.
500
DOUBLE POINTS!
The explosive eruption of Mount St. Helens in 1980 blew off the top of the mountain. Explain how dissolved gases caused Mount St. Helens to erupt explosively.
What is The trapped gases build up pressure until they explode. The erupting gases and steam push the magma out of the volcano with incredible force.
500
What do we call a volcano that has not erupted in a long time but scientists believe that it may erupt sometime in the future?