Hazardous Earth Flashcards

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1
Q

Where are explosive eruptions found and what types of lava are associated with them?

A

Convergent boundaries, rhyolite and andesite lava

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2
Q

Where are effusive eruptions found and what type of lava is associated with them?

A

Divergent boundaries, basalt lava

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3
Q

Give characteristics of rhyolitic/andesitic lava and the style of eruption it produces.

A
  • Highly acidic/silica content 70%, high viscosity, 750-900ºC
  • Violent, gas bubbles burst at surface, highly explosive, vent and cone often shattered
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4
Q

Give characteristics of basaltic lava and the style of eruption it produces.

A
  • Less acidic/silica content 50%, low viscosity, 1100-1200ºC

- Bubbles expand freely, limited explosive force

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5
Q

What are the materials erupted by an explosive eruption?

A

Gas, dust, ash, lava bombs, tephra

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6
Q

What materials are erupted by an effusive eruption?

A

Gas, lava flows

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7
Q

How frequently do explosive eruptions occur?

A

Not often, tend to have long periods with no activity

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8
Q

How frequently do effusive eruptions occur?

A

More often, tend to be more frequent and can continue for many months

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9
Q

What shape of volcano is associated with explosive eruptions?

A

Steep-sided strato-volcanoes, caldera

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10
Q

What shape of volcano is associated with effusive eruptions?

A

Gently sloping sides, shield volcanoes; lava plateaux

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11
Q

Give an example of a group of islands produced by a hot spot.

A

The Hawaiian islands

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12
Q

What are lava flows?

A

Streams of molten rock from an erupting vent

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13
Q

How are lava flows hazardous?

A

As lava is extremely hot (1000ºC) flows can cause fires and destroy crops and infrastructure

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14
Q

Do lava flows often cause injuries and fatalities?

A

No as even low viscosity lava does not move that rapidly

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15
Q

What are pyroclastic flows?

A

A dense, fast-moving flow of solidified lava pieces, volcanic ash, and hot gases

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16
Q

How are pyroclastic flows hazardous?

A

They move at up to 600km per hour, combined with extremely hot, poisonous gases and rock debris, destroying crops, infrastructure and anything in its path

17
Q

Do pyroclastic flows cause injuries and fatalities?

A

Yes, many as they cannot be outrun and kill instantly

18
Q

What are gas emissions?

A

Gases including carbon monoxide (CO), carbon dioxide (CO2), sulphur dioxide (SO2) are emitted from the vent of a volcano

19
Q

How are gas emissions hazardous?

A

CO and CO2 are colourless and odourless