Volcanoes

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Volcanoes. View From Space - Klyuchevskaya, Russia. Shiveluch, Russia. Cleveland Volcano, Alaska. Mount Etna From Space. Mount Etna From Space. Mount Etna From Space. Mount Etna. Magma – molten rock beneath the surface Lava – molten rock on the surface. Where Does Magma Come From?. - PowerPoint PPT Presentation

Transcript of Volcanoes

Volcanoes

View From Space - Klyuchevskaya, Russia

Shiveluch, Russia

Cleveland Volcano, Alaska

Mount Etna From Space

Mount Etna From Space

Mount Etna From Space

Mount Etna

Magma – molten rock beneath the surface

Lava – molten rock on the surface

Where Does Magma Come From?• Earth’s interior is hot (25 C/km near surface

= 1000 C at 40 km)• Pressure inhibits melting– Mantle is solid– Never far below melting point

• Volcanoes fed by small pockets 0-100 km deep– Rising hot material may melt– Water can lower melting point

Why Igneous Rock Classification Matters• Silica Content = Viscosity• Silica Content Governs Violence of

Eruptions– Silica Poor (Basalt): Fluid lavas, generally little

explosive activity– Intermediate Lavas (Andesite): Pasty lavas,

explosive eruptions common– Silica-Rich Lavas (Rhyolite): Extremely viscous

lava and explosive eruptions

Types of Volcanoes

Bowen's Series and Volcanoes

Volcanic Rocks(Rare) Basalt Andesite Rhyolite

Plutonic RocksDunite Gabbro Diorite Granite

Fluid Lava Is... ViscousMild Eruptions Violent

Type of VolcanoShield Volcano Stratovolcano Plug Dome

A Cinder Cone:

Wizard Island, Crater Lake, Oregon

Anatomy of a Cinder Cone, Hawaii

Shield Volcano: Haleakala, Hawaii

Eyjafjallajokull, Iceland

Stratovolcano: Mount Shasta, California

Lava Dome, California

Products of Eruptions

Lava Flows Pyroclastic Debris • Bombs • Lapilli • Ash MudflowsLandslides

Gases • Steam • Carbon Dioxide • H2S

• SO2

• HCl • HF

Environmental Hazards of Volcanoes

Pollution • SO2, HCl in Water Lava Flows Falling Ejecta Ash Falls • Building Collapse • Crop Destruction

Mudflows • Direct Damage

(Colombia, 1985) • Floods (Several Types)Blast (Mt. St. Helens, 1980) Pyroclastic Flow (St. Pierre,

1902) Gas (Lake Nyos, Cameroon,

1986)

Pyroclastic Flow or Nuee Ardente (French: Fiery Cloud)

How Calderas Form

Crater Lake, Oregon

The Stump of Mount Mazama

Supervolcanoes?

• Magma Chamber Collapse (Yellowstone?)– Destruction of crops– Destruction of high technology– Economic Disruption– Climatic Effects

• Flood Basalts– Climatic Effects– Toxicity

Jemez Caldera, New Mexico

Jemez Caldera, New Mexico

Collapsing Volcanoes – Mount Rainier

Collapsing Volcanoes - Hawaii

Landslide, Mount Saint Helens

Shastina and Landslide Deposit

Mount Shasta and Landslide Deposit

Evolution of VolcanoesAn active volcanic landscape

Evolution of VolcanoesA volcanic landscape after a million years or so