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A weak spot in the crust where molten material, or magma comes to the surface
Volcano
A molten mixture of rock-forming substances, gases, and water from the mantle
Magma
When magma reaches the surface
Lava
A major volcanic belt formed by many volcanoes that rim the Pacific Ocean
Ring of Fire
Along the boundaries of diverging plates such as mid-ocean ridges
Where do most volcanoes form?
Along the rift valley lava pours out of cracks in the ocean floor
How do volcanoes form against mid-ocean ridges?
True
True or False
Volcanoes can form along diverging plate boundaries on land
True
True or False
Many Volcanoes form near converging plate boundaries where oceanic crust returns to the mantle
Older denser plates sink beneath a deep ocean trench into the mantle. Some rock above, subducting plates melt and forms magma. Magma is less dense so it comes up eventually breaking through the ocean floor creating a volcano
How does subduction at converging plate boundaries lead to the formation of volcanoes?
Volcanoes at boundaries where two oceanic plates collide creating a string of islands
Island Arc
Japan, New Zealand, Indonesia, Philippines, Carribean Island
What are the major arcs?
a continental plate and an oceanic plate
What plates collided to form the Andes Mountains on the west coast of South America?
Where material from deep within the mantle rises and melts(the start of a volcano)
Hot Spot
Pacific plates drifted over a hot spot where Hawaii is now located
How did the Hawaiian Islands form?
False, also continental crust
True or False
Hot spots form only under oceanic crust
A substance that cannot be broken down into other substances
Element
True
True or False
When frozen water melts, it is undergoing a physical change
1) When paper is burned, it forms ashes
2) An iron chair will develop rust if oxygen combines with the iron
What indicates a chemical property?
milk and orange juice
What liquids have low viscosity?
Depends on silica content and temperature
What factors determine the viscosity of magma?
1) It makes magma thicker
2) It produces light-colored lava
What does silica do?
a rock that forms from light-colored lava
Rhyolite
a rock that forms from low-silica magma
Basalt
Hot, fast-moving lava
Pahoehoe
Cool, slow-moving lava
aa
Viscosity decreases
What happens to viscosity as temperature increases?
the temperature is lower and the silica content is higher
What happens when the viscosity of magma is higher?
the temperature is higher and the silica content is lower
What happens when the viscosity of magma is lower?
False, asthenosphere
True or False?
Magma forms in the lithosphere
True
True or False?
Liquid magma rises until it reaches the surface, or until it becomes trapped beneath the layers of rock.
1) pocket of magma beneath the surface
2) crack to the surface
What do all volcanoes have in common?
the area covered by lava as it pours out of a vent
What is lava flow?
at the top of a volcano around the central vent
Where does a crater form?
Carbon dioxide dissolved in soda pop rushes out when the pop is opened
What is a good model of a volcano erupting?
You cannot see the carbon dioxide gases but once the rock releases from pressure the carbon dioxide releases and allows the volcano to explode
What happens during a volcanic eruption?
The force of the expanding gases push the magma from the chamber through the pipe until it flows or explodes out of the vent
What factors determine the force of a volcanic eruption?
False, low in silica
True or False?
A volcano erupts quietly if its magma is thick and sticky.
Fine rocky particles as small as a speck of dust
Volcanic ash
Pebble-sized particles
Cinders
Particles ranging from the size of a baseball to the size of a car
Bombs
Occurs when an explosive eruption hurls out a mixture of hot gases, ash, cinders, and bombs (surge)
What is pyroclastic flow?
False, far away too
True or False?
Volcanic eruptions cause damage only when they are too close to the crater's rim.
Can belch out hot clouds of deadly gases as well as ashes, cinders, and bombs, can bury entire towns, if wet roofs will collapse, jet plane engines may stall from ash, cause landslides
What kinds of damage can volcanoes cause?
True
True or False?
The activity of a volcano may last from less than a decade to more than 10 million years.
False
True or False?
Most long-lived volcanoes erupt continuously.
Unlikely to erupt ever again
Extinct Volcano
No longer active but may become active again
Dormant Volcano
Erupting or showing signs that it soon will erupt
Active Volcano
False, anytime
True or False?
The length of time between eruptions of a dormant volcano is always less than a thousand years.
It can happen at anytime but that also means it may not be for another 100 years so they could live in fear
Why might people living near a dormant volcano be unaware of the danger?
1) Geologists are more successful in predicting volcanic eruptions than earthquakes
2) Geologists cannot predict what type of eruption a volcano will produce
What goes into the factor of predicting volcanoes?
1) Shield Volcanoes
2) Cinder Cone Volcano
3) Composite Volcanoes
4) Lava Plateaus
What are four landforms that form from ash and lava?
They form from many thin layers of lava
What is true about shield volcanoes?
False, ,shield volcanoes
True or False?
The Hawaiian Islands are cinder cone volcanoes.
Mount Fiji in Japan and Mount St.Helens in Washington state
Name two examples of composite volcanoes
True
True or False?
A composite volcano has both quiet and explosive eruptions
Gently sloping mountain formed by repeated lava flows
Shield Volcano
Cone-shaped mountain formed form ash, cinders, and bombs
Cinder Cone
Mountain formed by lava flows alternating with explosive eruptions
Composite Volcano
High, level area formed by repeated lava flows
Lava Plateau
Hole left by the collapse of a volcanic mountain
Caldera
It releases potassium and phosphourus
What happens when volcanic ash breaks down?
1) Volcanic Neck
2) Dikes
3) Sills
4) Batholiths
5) Dome mountains
What are 5 features formed by magma?
A mass of rock formed when a large body of magma cools inside the crust
Batholith
Baja, Sierra Nevada, Idaho, British Colombia
Where is an example of batholith in the United States?
True
True or False?
A dome mountain forms when hardened magma is uplifted and pushes up horizontal layers of rock.
True
True or False?
Some types of volcanic activity do not involve the eruption of lava.
When groundwater heated by a nearby body of magma rises to the surface and collects in a natural pool
Hot Springs
A fountain of water and steam that erupts from the ground
Geyser
Steam from underground is piped into turbines
How can geothermal energy be converted to electricity?
Bowl-shaped area that forms around a volcanoes central vent
Crater
Material found in magma that is formed from oxygen and silicon
Silica
When magma reaches the surface
lava
Slab that forms when magma forces itself across rock layers
Dike
Slab that forms when magma squeezes between layers of rock
Sill