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What is the density of magma compared to solid rock?
Magma is less dense than solid rock, allowing it to rise toward the Earth's surface.
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What affects magma density?
Magma density depends on its composition, particularly silica content and iron, as well as temperature and pressure
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What type of magma has low density?
Mafic magmas (low SiO2 content) are less dense and rise more easily.
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What is viscosity in magma?
Viscosity is the resistance to flow; it determines how easily magma can move.
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What is the effect of high viscosity in magma?
High viscosity magma is more resistant to flow, leading to explosive eruptions.
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What type of magma is associated with explosive eruptions?
High viscosity magmas with more silica (e.g., rhyolitic magmas).
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What type of magma leads to effusive eruptions?
Low viscosity magmas (e.g., basaltic magmas) flow more easily.
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How does gas content affect volcanic eruptions?
Higher gas content increases explosivity of eruptions.
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What is the silica content of mafic magmas?
Mafic magmas have low silica content (45-52% SiO2).
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What type of rock do mafic magmas form?
Mafic magmas form dark-colored basalts.
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What is the silica content range for intermediate magmas?
Intermediate magmas have moderate silica content (52-68% SiO2).
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What type of volcano is associated with intermediate magmas?
Stratovolcanoes are often formed from intermediate magmas (e.g., andesite).
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What is the silica content of felsic magmas?
Felsic magmas have high silica content (>68% SiO2).
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What type of eruptions do felsic magmas lead to?
Felsic magmas lead to explosive eruptions due to their high viscosity.
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What are pyroclastic materials?
Pyroclastic materials include ash, lapilli, and volcanic bombs from explosive eruptions. Ejected during explosive eruptions: ash (<2 mm), lapilli (2-64 mm), blocks or bombs (> 64 mm).
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What characterizes effusive eruptions?
Effusive eruptions occur with low-viscosity magmas allowing gas to escape.
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What is the texture of pahoehoe lava?
Pahoehoe lava has a smooth, ropy texture and low viscosity.
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What distinguishes a'a lava from pahoehoe?
A'a lava has a rough, jagged texture and higher viscosity than pahoehoe.
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What type of eruptions do phreatomagmatic eruptions involve?
Phreatomagmatic eruptions occur when magma interacts with water, causing explosions.
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What is the morphology of shield volcanoes?
Shield volcanoes are broad, dome-shaped with low, wide slopes, and this is due to the slow flowing nature of the magma it expels, which slowly cools and layers around the volcano vent to its base, forming a softer sloped shape.
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What rock type is associated with shield volcanoes?
Shield volcanoes are primarily composed of basalt (mafic).
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What is the eruption style of stratovolcanoes?
Stratovolcanoes have alternating explosive and effusive eruptions.
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What rock types are found in stratovolcanoes?
Stratovolcanoes are composed of andesite to rhyolite (intermediate to felsic).
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What defines the morphology of cinder cones?
Cinder cones are steep, conical hills built from volcanic debris.
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What type of rock is associated with pyroclastic debris?
Basalt (mafic)
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What is the eruption style of basalt?
Explosive, producing small pyroclasts
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What is the morphology of calderas?
Large depressions formed by collapse after a massive eruption
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What type of rock is found in calderas?
Rhyolite (felsic)
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What is the eruption style of rhyolite?
Highly explosive
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What are lava flows?
Fluid eruptions of lava that travel slowly down slopes
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What are fire fountains?
Jets of lava ejected during eruptions, forming fountains
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What are lava bombs?
Masses of partially molten rock, larger than 64mm in diameter, ejected from volcanoes during highly explosive eruptions
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What is volcanic ash?
Fine particles of fragmented volcanic rock
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What hazards do lava flows pose?
Destroy infrastructure, slow-moving but affect large areas
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What hazards do fire fountains and lava bombs pose?
Can cause fires and damage infrastructure, whilst being a threat in injuring or killing local civilians through impact or severe burns, and can damage nearby vegetation.
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What is the danger of ash fall?
Can collapse roofs and damage infrastructure, harm lungs and cause respiratory issues, disrupt transport, affect climate
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What are pyroclastic flows?
Fast-moving currents of hot gas and volcanic matter
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What are lahars?
Volcanic mudflows formed by water mixing with ash
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What are volcanic domes?
Mounds of highly viscous lava that build up over the vent
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What are sector collapses?
Large portions of a volcano’s flank collapsing due to destabilization
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What are lateral blasts?
Explosive eruptions that eject material sideways
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What are toxic gases released by volcanoes?
Gases like CO2, SO2, H2S that can suffocate and cause acid rain
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What is the Volcanic Explosivity Index (VEI)?
A scale from 0 to 8 measuring eruption explosiveness
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What does VEI 0-1 indicate?
Non-explosive eruptions, like lava flows
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What does VEI 2-3 indicate?
Mild eruptions with moderate explosions
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What does VEI 4-5 indicate?
Explosive eruptions with significant pyroclastic material
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What does VEI 6-8 indicate?
Catastrophic eruptions capable of ejecting massive amounts of pyroclastic material and having potential global impact. (e.g., Mount St. Helens VEI 5)
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What is seismic monitoring used for?
Detects ground vibrations, providing insight into magma movement to predict whether a volcanic eruption is going to occur or not,
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What do GPS and tiltmeters detect?
GPS and tiltmeters are used to detect subtle changes in a volcano's surface, including ground deformation (bulging or swelling) and tilting, which can indicate magma movement beneath the surface and potentially an impending eruption.
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What does gas monitoring (COSPEC) measure?
Sulfur dioxide emissions
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What does InSAR measure?
Ground deformation over large areas using satellite radar
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What does LIDAR measure?
Surface elevation changes using lasers
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What does thermal imagery (FLIR) detect?
Heat from lava flows or domes
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What is the purpose of volcanic hazard maps?
Identify and quantify volcanic hazards in surrounding areas
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What are the uses of volcanic hazard maps?
Essential for planning, evacuation routes, and risk mitigation
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What does mapping volcanic hazards involve?
Use geological data, eruption history, and monitoring data
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What is involved in risk assessment for volcanic hazards?
Evaluate risks based on proximity to active volcanoes
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What are potential volcanic hazards in Vancouver and Lower Mainland?
Pyroclastic flows, lava flows, and ash fall
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Where do 80% of active volcanoes occur?
Along convergent plate boundaries (Ring of Fire)
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What are hotspot volcanoes?
Hotspot volcanoes are volcanic features formed above unusually hot regions in the Earth's mantle, called mantle plumes, that are relatively stationary, and as tectonic plates move over them, they create chains of volcanoes.
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Where do volcanoes commonly form in subduction zones?
Along ocean-ocean and ocean-continent convergent boundaries
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Where do volcanoes form in divergent zones?
At tectonic plates moving apart
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What do oceanic plates form?
Chains like the Hawaiian Islands
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Where are subduction zones common?
Along ocean-ocean and ocean-continent convergent boundaries
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Where do volcanoes form in divergent zones?
Along mid-ocean ridges (e.g., Iceland)
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What type of eruptions occur at divergent boundaries?
Effusive, Basaltic lava flows, forming shield volcanoes
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What types of volcanoes are found at convergent boundaries?
Composite volcanoes with explosive eruptions
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What is an example of ocean-ocean convergent boundaries?
Aleutians
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What is an example of ocean-continent convergent boundaries?
Cascades
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What is rare at transform boundaries?
Volcanism
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What type of volcanoes do oceanic hotspots form?
Shield volcanoes (e.g., Hawaii)
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What type of lava do oceanic hotspots produce?
Mafic lava
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What do continental hotspots form?
Explosive calderas (e.g., Yellowstone)
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What type of lava do continental hotspots produce?
Felsic lava
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What is the tectonic setting of British Columbia?
Convergent margin (subduction of Juan de Fuca Plate)
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What is the dominant volcano type in British Columbia?
Composite volcanoes (e.g., Mount St. Helens, Mount Rainier)
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What potential activity is associated with British Columbia's tectonic setting?
Potential caldera activity (e.g., Yellowstone hotspot)
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What are all the main types of Volcanoes?
The main types of volcanoes, based on their structure and eruptive style, are cinder cones, composite (or stratovolcanoes), shield volcanoes, and lava domes.
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What is the density of magma compared to solid rock?
Magma is less dense than solid rock, allowing it to rise toward the Earth's surface.
What affects magma density?
Magma density depends on its composition, particularly silica content and iron, as well as temperature and pressure
What type of magma has low density?
Mafic magmas (low SiO2 content) are less dense and rise more easily.
What is viscosity in magma?
Viscosity is the resistance to flow; it determines how easily magma can move.
What is the effect of high viscosity in magma?
High viscosity magma is more resistant to flow, leading to explosive eruptions.
What type of magma is associated with explosive eruptions?
High viscosity magmas with more silica (e.g., rhyolitic magmas).
What type of magma leads to effusive eruptions?
Low viscosity magmas (e.g., basaltic magmas) flow more easily.
How does gas content affect volcanic eruptions?
Higher gas content increases explosivity of eruptions.
What is the silica content of mafic magmas?
Mafic magmas have low silica content (45-52% SiO2).
What type of rock do mafic magmas form?
Mafic magmas form dark-colored basalts.
What is the silica content range for intermediate magmas?
Intermediate magmas have moderate silica content (52-68% SiO2).
What type of volcano is associated with intermediate magmas?
Stratovolcanoes are often formed from intermediate magmas (e.g., andesite).
What is the silica content of felsic magmas?
Felsic magmas have high silica content (>68% SiO2).
What type of eruptions do felsic magmas lead to?
Felsic magmas lead to explosive eruptions due to their high viscosity.
What are pyroclastic materials?
Pyroclastic materials include ash, lapilli, and volcanic bombs from explosive eruptions. Ejected during explosive eruptions: ash (<2 mm), lapilli (2-64 mm), blocks or bombs (> 64 mm).
What characterizes effusive eruptions?
Effusive eruptions occur with low-viscosity magmas allowing gas to escape.
What is the texture of pahoehoe lava?
Pahoehoe lava has a smooth, ropy texture and low viscosity.
What distinguishes a'a lava from pahoehoe?
A'a lava has a rough, jagged texture and higher viscosity than pahoehoe.
What type of eruptions do phreatomagmatic eruptions involve?
Phreatomagmatic eruptions occur when magma interacts with water, causing explosions.
What is the morphology of shield volcanoes?
Shield volcanoes are broad, dome-shaped with low, wide slopes, and this is due to the slow flowing nature of the magma it expels, which slowly cools and layers around the volcano vent to its base, forming a softer sloped shape.
What rock type is associated with shield volcanoes?
Shield volcanoes are primarily composed of basalt (mafic).
What is the eruption style of stratovolcanoes?
Stratovolcanoes have alternating explosive and effusive eruptions.
What rock types are found in stratovolcanoes?
Stratovolcanoes are composed of andesite to rhyolite (intermediate to felsic).
What defines the morphology of cinder cones?
Cinder cones are steep, conical hills built from volcanic debris.
What type of rock is associated with pyroclastic debris?
Basalt (mafic)
What is the eruption style of basalt?
Explosive, producing small pyroclasts
What is the morphology of calderas?
Large depressions formed by collapse after a massive eruption
What type of rock is found in calderas?
Rhyolite (felsic)
What is the eruption style of rhyolite?
Highly explosive
What are lava flows?
Fluid eruptions of lava that travel slowly down slopes
What are fire fountains?
Jets of lava ejected during eruptions, forming fountains
What are lava bombs?
Masses of partially molten rock, larger than 64mm in diameter, ejected from volcanoes during highly explosive eruptions
What is volcanic ash?
Fine particles of fragmented volcanic rock
What hazards do lava flows pose?
Destroy infrastructure, slow-moving but affect large areas
What hazards do fire fountains and lava bombs pose?
Can cause fires and damage infrastructure, whilst being a threat in injuring or killing local civilians through impact or severe burns, and can damage nearby vegetation.
What is the danger of ash fall?
Can collapse roofs and damage infrastructure, harm lungs and cause respiratory issues, disrupt transport, affect climate
What are pyroclastic flows?
Fast-moving currents of hot gas and volcanic matter
What are lahars?
Volcanic mudflows formed by water mixing with ash
What are volcanic domes?
Mounds of highly viscous lava that build up over the vent
What are sector collapses?
Large portions of a volcano’s flank collapsing due to destabilization
What are lateral blasts?
Explosive eruptions that eject material sideways
What are toxic gases released by volcanoes?
Gases like CO2, SO2, H2S that can suffocate and cause acid rain
What is the Volcanic Explosivity Index (VEI)?
A scale from 0 to 8 measuring eruption explosiveness
What does VEI 0-1 indicate?
Non-explosive eruptions, like lava flows
What does VEI 2-3 indicate?
Mild eruptions with moderate explosions
What does VEI 4-5 indicate?
Explosive eruptions with significant pyroclastic material
What does VEI 6-8 indicate?
Catastrophic eruptions capable of ejecting massive amounts of pyroclastic material and having potential global impact. (e.g., Mount St. Helens VEI 5)
What is seismic monitoring used for?
Detects ground vibrations, providing insight into magma movement to predict whether a volcanic eruption is going to occur or not,
What do GPS and tiltmeters detect?
GPS and tiltmeters are used to detect subtle changes in a volcano's surface, including ground deformation (bulging or swelling) and tilting, which can indicate magma movement beneath the surface and potentially an impending eruption.
What does gas monitoring (COSPEC) measure?
Sulfur dioxide emissions
What does InSAR measure?
Ground deformation over large areas using satellite radar
What does LIDAR measure?
Surface elevation changes using lasers
What does thermal imagery (FLIR) detect?
Heat from lava flows or domes
What is the purpose of volcanic hazard maps?
Identify and quantify volcanic hazards in surrounding areas
What are the uses of volcanic hazard maps?
Essential for planning, evacuation routes, and risk mitigation
What does mapping volcanic hazards involve?
Use geological data, eruption history, and monitoring data
What is involved in risk assessment for volcanic hazards?
Evaluate risks based on proximity to active volcanoes
What are potential volcanic hazards in Vancouver and Lower Mainland?
Pyroclastic flows, lava flows, and ash fall
Where do 80% of active volcanoes occur?
Along convergent plate boundaries (Ring of Fire)
What are hotspot volcanoes?
Hotspot volcanoes are volcanic features formed above unusually hot regions in the Earth's mantle, called mantle plumes, that are relatively stationary, and as tectonic plates move over them, they create chains of volcanoes.
Where do volcanoes commonly form in subduction zones?
Along ocean-ocean and ocean-continent convergent boundaries
Where do volcanoes form in divergent zones?
At tectonic plates moving apart
What do oceanic plates form?
Chains like the Hawaiian Islands
Where are subduction zones common?
Along ocean-ocean and ocean-continent convergent boundaries
Where do volcanoes form in divergent zones?
Along mid-ocean ridges (e.g., Iceland)
What type of eruptions occur at divergent boundaries?
Effusive, Basaltic lava flows, forming shield volcanoes
What types of volcanoes are found at convergent boundaries?
Composite volcanoes with explosive eruptions
What is an example of ocean-ocean convergent boundaries?
Aleutians
What is an example of ocean-continent convergent boundaries?
Cascades
What is rare at transform boundaries?
Volcanism
What type of volcanoes do oceanic hotspots form?
Shield volcanoes (e.g., Hawaii)
What type of lava do oceanic hotspots produce?
Mafic lava
What do continental hotspots form?
Explosive calderas (e.g., Yellowstone)
What type of lava do continental hotspots produce?
Felsic lava
What is the tectonic setting of British Columbia?
Convergent margin (subduction of Juan de Fuca Plate)
What is the dominant volcano type in British Columbia?
Composite volcanoes (e.g., Mount St. Helens, Mount Rainier)
What potential activity is associated with British Columbia's tectonic setting?
Potential caldera activity (e.g., Yellowstone hotspot)
What are all the main types of Volcanoes?
The main types of volcanoes, based on their structure and eruptive style, are cinder cones, composite (or stratovolcanoes), shield volcanoes, and lava domes.
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