Volcanoes

Question 1

Name four primary volcanic hazards

Answer 1

Lava flows, pyroclastic flows, tephra and ash fall and gas eruptions

Question 2

Describe lava flows

Answer 2

A stream of lava as hot as 1170C and may take years to cool completely but are too slow to be a threat e.g. Kilauea, Hawaii 2014

Question 3

Describe pyroclastic flows

Answer 3

Mixture of dense hot rock, lava, ash and gases, they’re very dangerous as they move very quickly at approx. 100km/hr at temperatures of 700C e.g. Mount Sinabong, Sumatra 2015

Question 4

Describe tephra and ash fall

Answer 4

Volcanic rock and ash, tephra can cause injury and death and the ash causes poor visibility, slippery roads, collapsing roofs and faulty engines up to kilometres away from the volcano e.g. Eyjafijallajokul, Iceland 2010

Question 5

Describe gas eruptions

Answer 5

Magma contains dissolved gases including sulphur dioxide which cause pollution up to thousands of kilometres away from the eruption e.g. Mount Pinatubo, Philippines 1991

Question 6

Name two secondary volcanic hazards

Answer 6

Lahars and Jokulhlaup

Question 7

Describe lahars

Answer 7

Mud, water and rock travelling down the side of the volcano

Question 8

Describe jokulhlaup

Answer 8

Heavy and sudden floods formed by volcanoes melting glaciers so they may carry rock, gravel, ice and debris risking both lives and infrastructure e.g. Grimsvotn, Iceland 1934

Question 9

Give three key facts of the 2010 Iceland volcanic eruption

Answer 9

• 2.5km wide
• 11,000m ash plume
• 700 people evacuated

Question 10

Give two social impacts of the 2010 Iceland volcanic eruption

Answer 10

• Flights cancelled for a week

- 10 million passengers stranded

Question 11

Give five economic impacts of the 2010 Iceland volcanic eruption

Answer 11

• Global airlines lost $1.7bn in revenue
• European economy lost $5bn
• Kenya lost $1.3bn a day in revenue
• Increased Icelandic tourism
• 30% of global airline capacity cut (75% of European airline capacity)

Question 12

Give three environmental impacts of the 2010 Iceland volcanic eruption

Answer 12

• Rivers rose by 80cm
• Ash madeland fertile
• 20 farms destroyed

Question 13

What was the vulnerability of Iceland for the 2010 eruption?

Answer 13

30 minute warning system so no one died

Question 14

Give three key facts of the 2002 volcanic eruption in Nyiragongo, DRC

Answer 14

• 3470m high
• Stratovolcano
• Erupted 34 times since 1882

Question 15

Give five social impacts of the 2002 DRC volcanic eruption

Answer 15

• 147 people died from CO2 suffocation
• 120k homeless
• 400k evacuated
• 2 out of 4 hospital buried in 2m of lava
• Looting of empty homes

Question 16

Give three economic impacts of the 2002 DRC volcanic eruption

Answer 16

• Lava covered Goma airport
• 80% of commercial infrastructure destroyed
• 4,500 buildings destroyed

Question 17

Give one environmental impact of the 2002 DRC volcanic eruptions

Answer 17

High sulphur and methane emissions

Question 18

Why was the DRC so vulnerable?

Answer 18

• Early tremours not acted on
• No where to go as Niriwanda couldn’t cope with refugees
• Due to political status MEDCs reluctant to provide aid

Question 19

Describe the temperature of each type of lava

Answer 19

Basaltic - 1000-1200C
Andesitic - 800-1000C
Rhyolitic - 650-800C

Question 20

Describe the main minerals of basaltic lava

Answer 20

50% silica
water, gas and aluminium
High CO2, iron and magnesium

Question 21

Describe the main minerals of andesitic lava

Answer 21

60% silica
High water and hydrochloric acid
Low SO2

Question 22

Describe the main minerals of rhyolitic lava

Answer 22

70% silica
Potassium, sodium and aluminium
Low iron and magnesium

Question 23

What is the gas content of each types of lava

Answer 23

B - 0.5-2%
A - 3-4%
R - 4-6%

Question 24

How are each type of lava formed?

Answer 24

B - melting of mantle minerals
A - subducted oceanic plate melts and mixes with seawater, lithospheric mantle and continental rocks
R - melting of lithospheric mantle and slabs of previously subducted plates

Question 25

What are the flow characteristics of each type of lava

Answer 25

B - Thin and runny
A - Slow traps gases
R - Thick and stiff traps gases

Question 26

Describe the eruption energy of each type of lava

Answer 26

B - Gentle
A - Slow
R - Violent

Question 27

What location can each type of lava can be found

Answer 27

B - ocean hot spots, mid-ocean ridges, shield volcanoes
A - Composite cone volcanoes and subduction zones
R - Super or composite cone volcanoes

Question 28

Give an example of a volcano where each type of lava can be found

Answer 28

B - Mauna Loa
A - Chances Peak
R - Taupo

Question 29

Describe the Volcanic Explosivity Index

Answer 29

• 0-8 based on magnitude and eruption
• Logarithmic
• Determined by amount and height of material ejected, duration of eruption and qualitative description

Question 30

Describe 1,3,5,7 of the VEI

Answer 30

1 - less than 10(6)m of ejected material, small and gentle eruption Hawaiian type
3 - moderate to large eruption up to 10(8) material lasting up to half a day Strombolian type
5 - 10(10)m ejected and an eruption column of 28km high, cataclysmic event and composite cone e.g. Mount St Helens
7 - 10(12)m over 47km column height, composite cone ultra-Plinian type

Question 31

Describe level 3 of the tsunami intensity scale

Answer 31

2m run up height, light vessels carried away and reversed river flow

Question 32

Describe level 4 of the tsunami intensity scale

Answer 32

4m run up height, shore flooded to some depth, scouring of the land and structures damaged and large vessels swept inland

Question 33

Describe level 5 of the tsunami intensity scale

Answer 33

8m run up height, general flooding, coast littered with debris, people drowned and harbours damaged

Question 34

Describe level 6 of the tsunami intensity scale

Answer 34

16m run up height, complete destruction of many buildings some distance from shore, large ships damaged and many deaths