Volcanoes Flashcards

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1
Q

What is a volcano?

A

A mountain or hill, typically conical, having a crater or vent in which particles have or are being erupted from the earth’s crust.

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2
Q

How much volcanism occurs under the sea?

A

80%

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3
Q

How many volcanoes are potentially active?

A

1500

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4
Q

Why are there volcanoes?

A

They are a mechanism for heat and mass transfer from the earth’s crust

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5
Q

What type of volcanoes form on divergent margins?

A

Effusive volcanoes. Generally producing voluminous and pillow lava. Andesite volcanoes

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6
Q

What type of volcanoes are produced on convergent margins?

A

Low density. Continental or island arcs. Shield volcanoes

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7
Q

What type of volcanoes are produced on intraplate volcanoes?

A

Rhyolite volcanoes. Low viscosity, effusive eruptions.

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8
Q

What are the two eruption styles of volcanoes?

A

Effusive (forms lava domes or flows) and Explosive (fragmented magma)

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9
Q

State the credentials of Basalt volcanoes

A

Low viscosity. Low gas content. Low silica content

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10
Q

State the credentials of Rhyolite volcanoes

A

Plumes are buoyant. High viscosity, silica and gas content. Slow moving magma

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11
Q

What are pyroclastic flows?

A

Lava plume failure. High gas content. Fast travelling

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12
Q

How can H2O affect a volcano?

A

It can chill a lava flow. It can enhance explosivity through increased vigour.

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13
Q

State the credentials of fissure volcanoes

A

Formed on divergent plate margins.
Effusive basaltic magma.
Lateral lava flows

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14
Q

State the credentials of shield volcanoes

A

Basaltic lava flows.

Built by succession

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15
Q

State the credentials of composite cones

A

Successive pyroclastic and lava material.

All types of explosions and flows

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16
Q

State the credentials of caldera volcanoes

A

Collapsed structure.
All magma has been removed from the volcano during each eruption.
Highly explosive.
Ignimbrites - Large pyroclastic flows

17
Q

What are some benefits from volcanism?

A

Tourism - social and economic benefits
Geothermal energy - renewable energy, drives water circulation
Provides rich nutrients to soil.