Volcanic Hazards Flashcards

1
Q

Lists me 6 volcanic hazards

A
  • lava
  • gases
  • pyroclastic & ash fallout
  • pyroclastic flows
  • lahars
  • tephra
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2
Q

What is lava?

A

Magma above the surface

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3
Q

What is magma?

A

Molten rock

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4
Q

Give 3 facts about lava

A
  • speed of a lava flow depends on the materials making up the lava
  • thick lava flows are at risk of collapsing, which can cause pyroclastic flows
  • in the 2018 Kilauea volcanic eruption, lava flows destroyed homes and cars
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5
Q

Give 2 types of lava flows

A
  • Basalt flows are runnier and move faster
  • andesite flows are thicker (more viscous) and move slower
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6
Q

Basalt flows SiO2 percentage

A

50%

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7
Q

Andesite flows SiO2 percentage

A

70%

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8
Q

What gases does a volcano eruptions contain (2 things)

A

Sulphur dioxide and carbon dioxide

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9
Q

What can sulphur dioxide do?

A

Cause acid rain

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10
Q

What is a pyroclastic fallout?

A

Any material that has been ejected from the volcano and has travelled through the aid or atmosphere and fallen to earth

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11
Q

What is ash?

A

Tiny pieces of burnt rock fragments that are blown into the atmosphere, usually at some force

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12
Q

Example of an ash fallout

A

2010: ash from Eyjafjallajokull eruption in Iceland caused flights to be grounded because of the risk of damage to the plane engines

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13
Q

What’s another word for pyroclastic flows?

A

Nuées ardentes

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14
Q

What is a pyroclastic flow?

A
  • Currents of hot ash, lava and gas that can move downhill at speeds of up to 500km/h during an eruption
  • reach temps up to 1000 degrees and can cover distances to 30km
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15
Q

What is a lahar?

A

If volcanic ash or lava mix with water, lahars (mudflows) may form

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16
Q

Where can a lahar also happen?

A

When a volcano has a glacier

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17
Q

What is tephra?

A

Rock fragments that are ejected from the eruption

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18
Q

How far can tephra travel up to?

A

80km

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19
Q

What type of volcanoes are created in destructive plays margins

A

Composite volcanoes

20
Q

What are composite volcanoes like and why?

A

Explosive since the magma has large levels of gas and silica

21
Q

What type of volcanoes are made in constructive plate margins?

A

Shield volcanoes

22
Q

What are 3 key facts about shield volcanoes?

A
  • low silica content
  • less viscous (more runny)
  • lack of pressure
    This makes he volcanoes very large
23
Q

What are the 4 ways to predict volcanic hazards?

A
  • thermal images
  • seismic waves
  • gas emissions
  • volcanic swelling
24
Q

What does thermal images do?

A

Uses thermal images to record the magma movement

25
Q

What do seismic waves do?

A

Monitor earthquake tremors

26
Q

How do we use volcanic swelling?

A

Scientists can measure the rate of swelling and the angle the volcano is swelling at

27
Q

What is jökukhlaup?

A

Name of the flooding that happens when glaciers or ice caps melt

28
Q

Example of a lahar

A

1985: Armero tragedy took place when the Nevado De Ruiz volcano erupted in Columbia. 4 lahars came towards the town of Armero and killed 20,000

29
Q

Example of volcanic gases

A

1986 eruption of lake Nyos, Cameroon

30
Q

When did mt Merapi occur?

A

November 2010

31
Q

How many people died in merapi

A

353

32
Q

How many injured

A

500

33
Q

How many people successfully evacuated

A

350,000

34
Q

How much economic losses amounted to?

A

0.6 billion dollars

35
Q

What did the ash fall do?

A

Rice harvests on the mountains were lost

36
Q

What did the pyroclastic flows do

A

Forested areas were destroyed

37
Q

What also caused devastation

A

A lahar

38
Q

Where did the eruption come from?

A

Composite cone

39
Q

What was the VEI

A

4

40
Q

Where was the volcano situated at?

A

Subduction zone

41
Q

Between what 2 plates?

A

Indo-Australian and Eurasian

42
Q

What was the eruption like. 3 facts

A

Explosive
Thick andesite lava
Large pyroclastic flows

43
Q

How much did ash clouds surround the area

A

40km

44
Q

Why did many decide to ignore the warnings?

A

They believed some ‘spiritual guardian of the mountain’

45
Q

What was provided for survivors in terms of shelter? 2

A

Tents and tarpoulins

46
Q

What was provided for survivors in terms of edibles 3

A

Food, water and hygiene kits