overview of volcanoes gentle eruption = lava flows violent eruptions = pyroclastic flows
TRANSCRIPT
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Overview of Volcanoes
Composition SiO2 Content
Viscosity Volatile Content
Eruptive Behavior
Type of Volcano
Mafic 50% Low Low Gentle
Shield Volcano
Intermediate 60% Medium Medium Both Gentle & Violent
Composite Cone
Felsic 70% HIgh HIgh Violent
Volcanic Dome
Gentle Eruption = Lava Flows
Violent Eruptions = Pyroclastic Flows
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Types of Volcanoes
Compare the composition and size of a shield volcano
and a Composite Cone
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Shield Volcano - Big Island of Hawaii
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Lava Fountain
What is the viscosityof this lava?
It’s volatile content?
What’s its chemical composition?
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Lava River
Is this behaviorgentle or violent?
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Lava flow cause localized damage.
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When this lava coolsIt forms basalt
Two typesof flows
Aa
Pahoehoe
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Composite Cone - Philippines
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Anatomy of a Composite Cone
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Composite Cones Erupt Violently
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Composite Cones Also Erupt Gently
What is the viscosityof this lava?
It’s volatile content?
What’s its chemical composition?
When this lava cools it formsAndesite
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Volcanic Dome - Oregon
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Volcanic Domes Fail Suddenly
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SOME QUESTIONS
What is the viscosity of this lava?
It’s volatile content?
What’s its chemical composition?
When this lava cools it formsRhyolite
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• Lava Flows• Volatiles• Pyroclastic Explosions• Lahars• Tephra
Volcanic Hazards
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Volcanic Hazards - Lava Flows
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Volcanic Hazards - Volatilities - VOG
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Volcanic Hazards - Volatilities Carbon Dioxide Asphyxiation
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Volcanic Hazards - Volatilities - Laze
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Volcanic Hazards - Pyroclastic Explosion Nuee Ardente
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Volcanic Hazards - Lahar
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Lahars are caused by either:Intense rainfall around a volcanic summit
Suddenly melting snows and glaciers
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Volcanic Hazards - Tephra
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Tephra or Volcanic Ash is thickest closest to a volcanic eruption
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