3.1.5.3 Volcanic Hazards Flashcards

1
Q

what is a volcano

A

an opening in the crust of the earth that is connected to a magma chamber

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2
Q

what is ejected from a volcano

A

ash, pyroclastic flow, volcanic bombs, lava

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3
Q

what is a dormant volcano

A

hasnt erupted in the past 10,000 years

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4
Q

describe global distribution of volcanoes

A

95% found at plate boundaries
5% intra plate
high density, linear patter a long the ring of fire/subduction zones
above hot spots, iceland and hawaii
clustered at the east african rift valley e.g. mt kenya

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5
Q

characteristics of a shield volcano

A

found at constructive boundaries
purely basaltic lava is emitted
gentle slope
frequent, gentle eruptions

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6
Q

characteristics of a composite volcano

A
mainly at destructive boundaries
many vents on the side
cone shapes
layers of solidified lava
explosive
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7
Q

what is the most destructive type of volcano and what type of lava does it emit

A

Plinian - up to 55km high ash clouds that can cause global winter
rhyolitic lava

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8
Q

what is the least destructive type of volcano and what type of lava does it emit

A

icelandic

basaltic

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9
Q

what sort of lava do vulcanian/vesuvian volcanoes emit?

A

andesitic

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10
Q

what are primary effects of volcanic eruptions?

A
nuee ardente
tephra
gases ( Co2 and carbon monoxide)
lava
pyroclastic flow
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11
Q

secondary effects of a volcanic eruption

A
lahars
acid rain
flooding
tsunamis
climaate change
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12
Q

what are pyroclastic flows

A

ground hugging avalanches of hot ash, pumice, rock fragments and gas
exceed temperatures of 500 degrees c

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13
Q

when was the eyfajallajokull eruption

A

april 2010

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14
Q

where is the eyfajallajokull volcano located

A

mid atlantic ridge
beneath an ice cap in southern iceland
south east of the capital Reykjavik

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15
Q

how tall is the eyfajallajokull volcano

A

1666m

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16
Q

how high was lava ejected into the air?

A

150m

17
Q

how far did lava flow?

A

4km

18
Q

when did eyfajallajokull become explosive and what did it eject

A

14th April

fine, glass rich ash that reached 8km into the atmosphere which was deflected eastwards towards europe by westerly winds

19
Q

what were responses to the eyjfajallajokull eruption

A

500 farmers evacuated

roads closed in fear of flash floods

20
Q

what were impacts of the eyfajallajokull eruption

A

flights in europe were grounded for a week which cost airlines £2bn
there were dangers to livestock in scotland
thick layers of ash fell on farm pastures which made it difficult to continue farming livestock
river levels rose as the ice cap melted

21
Q

what factors made the eyfajallajokull eruption worse

A

it took place beneath glacial ice which resulted in melt water flowing back into the volcano creating toxic gas
located directly underneath the polar jetstream which was heading SE (towards europe)

22
Q

national impacts of the eyfajallajokull eruption

A

tourism numbers declined

reconstruction of roads that were destroyed by flooding was expensive

23
Q

what are positive impacts of the eyfajallajokull eruption

A

became a tourist attraction
local soils are nutrient rich and very fertile after the ash fell
geothermal energy is available