Test 2: Volcanism Flashcards
What are Pyroclastic Materials?
Magma fragments that are explosively ejected by volcanoes, most are solid.
Which Volcano?
Rhyolitic lava flows-most viscous
Very Explosive
Lava Domes
Which Volcano?
Layers of lava flows and pyroclastic debris Steep Cone Shaped Intermediate compositions-andesite Explosive “Ring of Fire”`
Composite Volcanoes
Which Volcano?
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Gentle slopes and rounded shapes
Basaltic lava flows
Non-Explosive
Hawaiian Volcanoes
Komotilite
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Shield Volcanoes
Which Volcano?
Pyroclastic materials
Steep cones
Rarely exceed 400 m high
Cinder Cones
True or False?
The shape and eruptive style of volcanoes are related to the chemistry and viscosity of their magmas.
True
The shape and eruptive style of volcanoes are related to the chemistry and viscosity of their magmas.
Rhyolitic lava flows:
Creates Lava Dome
Lava Dome holds in gases
Flows have broken and blocky surfaces
Andesitic lava flows:
Flows slowly
Cone shape
Made up of Pyroclastic and lava
Basaltic lava flows: Flows fast (30-50km/hr)
Flows fast (30-50km/hr)
Komatiite lava flows:
Has not erupted in about 2.5 billion years
Silica Content
Rhyolite:
High silica content (70-75%)
High Viscosity
Silica Content
Andesite:
Intermediate silica content (60-65%)
Intermediate Viscosity
Silica Content
Basalt:
Low silica content (50-55%)
Low Viscosity
Silica Content
Komatiite:
Limited Silica (Below 40%) Very Low Viscosity
Fine: (No big crystals) (It’s lave) (Came to the surface) (Cooled first, causing crystals not being able to grow)
Extrusive Igneous Rock
Basalt, Andesite, Rhyolite, Komatiite
Course: (Big Crystals) (Didn’t come to the surface)
Intrusive Igneous Rock
Granite, Diorite, Gabbro, Peridotite
What does Viscosity affect?
Viscosity affects the flow of lava and therefore the shape of the resulting volcano
In explosive eruptions, _____is ejected
In explosive eruptions, tephra is ejected
What is an accumulation of tephra called?
An accumulation of tephra is a Pyroclastic deposit
What is the term for anything that explodes out of the volcano?
Pyroclastic is anything that explodes out of the volcano
Molten rock material below the earth’s surface
Magma
Magma turns into a liquid when the surface is reached, creating lava
Lava
The viscosity of Magma is controlled by ______?
The viscosity of Magma is controlled by Silica Content
More Silica causes a ______explosion
More Silica causes a bigger explosion (Builds up pressure)
Less Silica makes for a ______explosion
Less Silica makes for a smaller explosion
How do we have magma?
Decompression (Weight onto of it, prevents it from being liquid)
Addition of volatiles (Adding water breaks chemical bonds, creating fluid)
Addition of heat (When magma comes up it warms adjacent material, turning it into liquid)
The tectonic setting determines the type of volcano
Mid-ocean ridges, subduction zones, hot spots
Mixing of Basalt and Granite create andesite which makes cone volcanoes
Subduction Zones
The tectonic setting determines the type of volcano
Mid-ocean ridges, subduction zones, hot spots
One section is moving one way and another section is moving a different way, the magma pushes through the weak spot creating lava.
Mid-Ocean Ridges
The tectonic setting determines the type of volcano
Mid-ocean ridges, subduction zones, hot spots
Magma is stationary, but the plates are moving so there is a build-up of magma pressure which creates small islands.
Hot Spots
Where does the Ring of Fire surround?
The Ring of Fire surrounds the Pacific Ocean. (Surrounds Pacific Ocean) (Subduction zones)
How many of all active volcanoes on land are located along the Ring of Fire which surrounds the Pacific Ocean?
2/3
Popular Volcanoes
Still active (Pompeii)
Mount Vesuvius, Italy
Popular Volcanoes
“Year without summer” (Ash shot in the air everywhere)
Tambora, Indonesia
Popular Volcanoes
57 people died) (Internal Explosion
Mount St Helens, United States
Popular Volcanoes
Airline disaster, ash coverings in sky
Mt. Eyjafjallajökull, Iceland
What are the volcanoes in Japan, Mexico, the Philippines, and Indonesia known as?
(Killer Volcanoes)
How many volcanoes erupt each year on Earth?
50-60 volcanoes erupt each year
Where are the most active volcanoes located in our solar system?
Jupiter’s moon - IO has the most active volcanoes
Tidal Forcing:
Moon’s gravitational pull on a planet
Jupiter’s mass is so massive that it squeezes the moon (IO), it heats up the moon causing lava flows.
Where is the largest volcanic mountain?
Olympus Mons has the largest volcanic mountain (Mars)
While Earth has more volcanic features, Mars has the largest
Magma pushes and silicifies, this creates a large pile up creating big volcanic features.
Volcanoes - Dormant
True or False:
All volcanoes are destructive
False:
Not all volcanoes are destructive
True or False:
Pyroclastic material is the most dangerous
True
Pyroclastic material is the most dangerous
How to get an accurate representation of the surface on Venus?
Radar can go through cloud cover (Gives an accurate representation of the surface)
How many major volcanoes or volcanic features are there on Venus?
1,600 major volcanoes or volcanic features
Is volcanism still on Venus?
Evidence shows that in the volcanic mountains there is still heat, meaning volcanism might still be on Venus.
What are volcanic gases primarily made up of?
Water Vapor (lesser amounts of carbon dioxide)
Craters:
Depressions formed by explosions or collapse of volcano top. (1km wide)
Calderas:
Volcano colossus into magma chamber following violent eruptions (thousands of metres across, hundreds of metres deep).
Lava Tubes:
Forms a crust which silicifies, causing the creation of a tunnel (50 km/hr)
Vents:
Any opening for lava and debris
Can produce flood basalts
Both on water and on land (Along mid-ocean ridge)
Hot Springs:
Hot rocks heat groundwater; discharge at the surface
Blue Lagoon
Geysers:
Groundwater boils, erupting at the surface. Water turns into steam and erupts
Yellowstone national park
Pyroclastic Sheet Deposits:
Huge sheet-like eruptions of pyroclastic materials
Where would you find Lava Lakes?
In Africa
Erupt beneath or against glaciers
Subglacial volcanoes erupt, rapidly melting ice and produce huge floods known as Jokulhlaups
Huge flood from glacier volcanoes (Iceland, Mt. Garibaldi)
Ice Contact Volcanoes:
Volcanic Hazards
Primary Effects:
Lava flows, ashfall, volcanic bombs, pyroclastic flows, pyroclastic surges, lateral blast (Mt.St.Helens), and poisonous gases.
Volcanic Hazards
Secondary Effects:
Lahars, debris avalanches, landslides, groundwater and surface contamination, floods, fires, and tsunamis.
The size of an eruption can be quantified using a scale called the ______?
Volcanic Explosivity Index (VEI)
Volcanic Hazards: Ash
Ash is blown high into the air and falls onto areas.
Ash can cause its own lightning from rubbing against each other.
Causes health hazards (It can burn you)
(Mt. Eyjafjallajokull)
Causes of volcanic ash
Vegetation Destroyed
Contaminates Surface Water
Damage to buildings
Aircraft Engine Failure
British Airways Flight 009:
Flew into a cloud of volcanic ash (Mt. Galunggung near Jakarta, Indonesia)
All 4 Engines went out
Biggest flight distribution since 9/11
The ash plume drifted between 6,700 m and 11000m (2000 km away)
Mt. Eyjafjallajokull:
Occurs when magma reaches the surface
Can move slowly or rapidly depending on viscosity and temperature
Lava Flows:
What is the most common lava flow?
Basaltic lava flows are the most common
Types of Lava Flows
Pahoehoe:
Hardens with a smooth ropy texture
Travels at speeds up to a few kilometres per hour
Types of Lava Flows
Aa:
Harden’s with a rough, blocky texture
More vicious travels at rates of a few metres per day
3 ways to Divert Lava Flows:
Bombing:
Hydraulic Chilling:
Wall Construction:
Diverting Lava Flow:
Bombing:
Block channels to cause low flows to take a less damaging route
Diverting Lava Flow:
Hydraulic Chilling:
Water used to chill and control lava flows (Iceland)
Diverting Lava Flow:
Wall Construction:
Walls are used to redirect lava flows
What is the most dangerous lava flow?
Pyroclastic flows are most dangerous (400 km per hour) Pompeii
Avalanches of hot rock, Ash, volcanic rock fragments
Flows
Dense clouds of hot gas and rock debris produced by explosive interaction of water and magma
Surges
Nuée Ardente:
A turbulent, fast-moving cloud of hot gas and ash erupted from a volcano
Lateral Blasts:
Rock fragments, gas, and ash that are blown horizontal from the side of the volcano
For example: Mount St. Helens
Lahars: Aftermath of Mt. St. Helens
Forecast eruptions but can’t predict them
Who believed the situation was over-exaggerated and ended up dying from not evacuating?
Harry Truman (Spirit Lake Lodge)
Poisonous Gas
Odourless, heavy gas that can displace breathable air.
Carbon dioxide (CO2):
Poisonous Gas
Odorous gas that causes acid rain and can contaminate rock and soil.
Sulphur Dioxide:
Lahars?
Large amounts of loose volcanic ash and other pyroclastic material become saturated with water and rapidly move downslope
Why Do People Live Near Volcanoes?
Place of birth On some islands, all land is volcanic Fertile land for farming Believe Interruption is unlikely Unaware of risk Economic limitations
Natural Service Functions:
Volcanic Soils:
Good for coffee, maize, pineapples, sugar cane, and grapes
Geothermal Power:
Can create energy for nearby urban areas
Mineral Resources:
Gold, silver, etc. And non-metallic rocks
Used for soap, building stone, aggregate for roads, railroads, etc
Recreation:
Health Spas in Hot Springs
Hygiene, snow sports, and education
Kilauea National Park
Creation of New Land:
Hawaiian Islands
Is it possible to Forecast Eruptions?
YES!
Monitoring involves recording and analyzing both physical and chemical changes at volcanoes.
Tiltmeters and geodimeters to detect changes in slope, elevation, and shape.
Seismometers to detect harmonic tremors
Gas emissions, thermal, magnetic and hydrologic monitoring are also measured
