3.1.5.3 Volcanic Hazards

Question 1

what is a volcano

Answer 1

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

Question 2

what is ejected from a volcano

Answer 2

ash, pyroclastic flow, volcanic bombs, lava

Question 3

what is a dormant volcano

Answer 3

hasnt erupted in the past 10,000 years

Question 4

describe global distribution of volcanoes

Answer 4

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

Question 5

characteristics of a shield volcano

Answer 5

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

Question 6

characteristics of a composite volcano

Answer 6

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

Question 7

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

Answer 7

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

Question 8

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

Answer 8

icelandic

basaltic

Question 9

what sort of lava do vulcanian/vesuvian volcanoes emit?

Answer 9

andesitic

Question 10

what are primary effects of volcanic eruptions?

Answer 10

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

Question 11

secondary effects of a volcanic eruption

Answer 11

lahars
acid rain
flooding
tsunamis
climaate change

Question 12

what are pyroclastic flows

Answer 12

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

Question 13

when was the eyfajallajokull eruption

Answer 13

april 2010

Question 14

where is the eyfajallajokull volcano located

Answer 14

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

Question 15

how tall is the eyfajallajokull volcano

Answer 15

1666m

Question 16

how high was lava ejected into the air?

Answer 16

150m

Question 17

how far did lava flow?

Answer 17

4km

Question 18

when did eyfajallajokull become explosive and what did it eject

Answer 18

14th April

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

Question 19

what were responses to the eyjfajallajokull eruption

Answer 19

500 farmers evacuated

roads closed in fear of flash floods

Question 20

what were impacts of the eyfajallajokull eruption

Answer 20

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

Question 21

what factors made the eyfajallajokull eruption worse

Answer 21

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)

Question 22

national impacts of the eyfajallajokull eruption

Answer 22

tourism numbers declined

reconstruction of roads that were destroyed by flooding was expensive

Question 23

what are positive impacts of the eyfajallajokull eruption

Answer 23

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