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A Level Geography - Plate tectonics and associated hazards > Volcanic case studies > Flashcards

Volcanic case studies Flashcards

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1
Q

When and where did the eruption of Pinatubo occur?

A

1991 - Philippines - RICH/POOR DIVIDE.
Philippine plate subducts the Eurasian plate.
Part of the Luzon volcanic arc.

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2
Q

What were the characteristics of Mount Pinatubo?

A

Rhyolitic magma - NO lava.
Ash cloud.
Stratovolcano - last erupted 500 years
Large caldera formed.

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3
Q

What happened prior to the Pinatubo eruption?

A

Predicted with 48 hours to spare - the US Geological Service helped predict it.
Allowed US airforce at the Clarke base to evacuate.

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4
Q

What were the hazards created by Pinatubo?

A

Ash fall – ash was ejected 25km into the air.
Ash cloud - 125,000km.
Pyroclastic flows - reached 4-5km.
Lahars.

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5
Q

What were the social impacts of Pinatubo? 4

A
  1. 900 deaths - 300 by collapsing roofs, 100 by lahars.
    0 US deaths – all deaths were Aeta tribe.
  2. 58,000 evacuated from 30km radius.
  3. 1.2 million lost homes.
  4. Forced migration to shanty towns in Manila.

POVERTY may be the biggest factor as many didn’t have a choice.

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6
Q

What were the economic impacts of Pinatubo? 6

A
  1. Houses/bridges destroyed.
  2. Manila airport closed - $700 Million
  3. 1991 harvest - destroyed.
  4. 650,000 people lost their jobs - lost livelihoods - lost ability to live properly (negative multiplier) - POVERTY.
  5. Electricity went off, water was contaminated, road links were destroyed, and telephone links were cut.
  6. $500 million total costs.
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7
Q

What were the environmental impacts of Pinatubo? 3

A
  1. Volcanic ash smothered buildings/land.
  2. Global cooling (0.5°C) - ash atmosphere.
    –15-30 millions tons of sulphur dioxide was discharged - blocked sunlight.
    BUT - this could contribute to the opposite of global warming (greenhouse gases raise Earth’s temperature).
  3. Lahars - severe river bank erosion.
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8
Q

What was the prediction of Pinatubo like? 3

A
  1. No monitoring until the 3rd of April but seismometers were put into place - NO US DEATHS.
  2. The United States Geological Service helped prediction - 48 hours to spare.
  3. Satellite images would’ve improved this.
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9
Q

What was the prevention of Pinatubo like? 4

A
  1. 58,000 evacuated up to a radius of 30km.
    USA air force helicopters helped - 0 US deaths.
  2. Alert systems.
  3. Government Shelters.
  4. Long term strategies/disease control would’ve improved this.
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10
Q

What was the preparation of Pinatubo like? 3

A
  1. Evacuation camps built for refugees.
  2. Warning sign like gas and steam looked for.
    Long/short term aid - Red Cross and the United States.
  3. Improved storage of medical supplies, food/water would’ve improved this.
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11
Q

When and where did the eruption of Soufriere Hills occur?

A

POOR.
Chances Peak (South part).
Destructive plate margin - forms the Peurto Rico Trench.
North American plate subducts the Caribbean plate.
Had been dormant for 300 years - but started to erupt in 1995.

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12
Q

What was the nature of the SH eruption?

A

1995 – steam emissions, many earthquakes, steam/ash reaching 2,500m.
1996 – ash cloud with dome growth and small pyroclastic flows.
1997 – most intense.
June climax – pyroclastic flows - 4-5 million m cubed.

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13
Q

How did the SH affect Monserrat?

A

Only 40km squared/100km squared of land is safe to live on.
Capital Plymouth – buried in 10+m of ash/mud.
Southern part uninhabitable.

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14
Q

What are the characteristics of the SH volcano?

A

Andesitic lava.
Stratovolcano.
Mushroom-shaped plume.

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15
Q

What were the SH hazards?

A

Pyroclastic flows/volcanic ash – pyroclastic flows flowed down the Tar River valley.
Heavy rainfall - lahars.
Plymouth - covered in layers of ash/mud.

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16
Q

What were the ECONOMIC impacts of the SH eruption? 6

A
  1. Collapse of the tourist/riceprocessing industries
  2. Unemployment rose - 7% to 50%.
  3. Agriculture stopped.
  4. Shortage of available building land
  5. 70% accommodation rent rise.
  6. Salem/St Johns - developed/repopulated.
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17
Q

What were the SOCIAL impacts of the SH eruption? 7

A
  1. Plymouth - 10m+ ash/mud covered.
  2. Many buildings destroyed - only hospital, the airport and many roads.
  3. Respiratory problems - ash.
  4. Psychological problems.
  5. Skills shortage as people left.
  6. 5,000 were living in temporary shelters - north.
  7. North - difficult to cope with the south influx.
  8. 19 deaths.
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18
Q

What was the hazard management like once the SH eruption had occurred? 8

A
  1. Exclusion zones.
  2. Evacuation of 7,000/11,000 population to neighbouring islands e.g. Antigua/UK resettlement.
  3. Resettlement to ‘safer’ north side - temporary shelters.
  4. Re-establishment of air/sea links with the island.
  5. Building of new permanent housing.
  6. Moving capital from Plymouth to Salem.
  7. Providing farm areas for north settlers.
  8. Setting up MVO to monitor volcanic activity – run under the BGS.
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19
Q

How how the Montserrat island redeveloped since the SH eruption? 5

A
  1. Restoration tourism attempts.
  2. UK refugee return – £100 million.
  3. New airport – Gerald’s - £11 million - opened in 2005.
  4. Developing port facilities at Little Bay.
  5. New football pitch – funded by FIFA.
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20
Q

How is the SH volcano NOW monitored? 6

A
  1. Seismograph network.
  2. Earth deformation meters/tiltmeters.
  3. Satellite location GPS.
  4. COSPEC - measures gas emissions.
  5. The pH of rainwater monitored - indication of the magmatic gas content.
  6. Geologists regularly flew into the most dangerous areas to sample new flow deposits, measure cracks and growth of the dome.
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21
Q

Where is the Eyjafjallajokull volcano located?

A 
Mid Atlantic Ridge, Iceland - RICH.
Constructive plate boundary.
North American plate (moving West) and the Eurasian Plate (moving East).
Rate of 1cm to 5 cm per year.
Fissure-fed lava flows occur.
22
Q

What are the characteristics of the Eyjaf?

A

Small, ice-covered, Strombolian volcano.
2.5 wide caldera.
Andesitic lava – ice cap created an unusual ash cloud.

23
Q

What happened in March 2010 Eyjaf?

A

2009 Seismic activity gradually increased in intensity.
20th March 2010 - a small eruption - VEI -1.
Andesitic lava and an effusive eruption.
Only a small ash ejection - 4km.

24
Q

What happened in April 2010 Eyjaf?

A

14th April 2010 - the explosive eruption ejected fine glass-ash to over 8km into the atmosphere.
VEI - 4.
Local conditions affected eruption - atypical eruption.

25
Q

What were primary/secondary hazards of Eyjaf?

A

Face masks worn/sun blocked out - gas emissions - P.
250 million cubic metres of tephra - S.
9km - ash plume - aircraft hazard - S.

26
Q

What were the social impacts of Eyjaf? 5

A
  1. 700 evacuated due to flooding – 150m thick ice cap had melted.
  2. 20 farms ruined by ash/flooding – 500 local farmers forced to leave.
  3. 10 million flights affected.
  4. Respiratory diseases increased.
  5. Roads closed – traffic congestion.
27
Q

What were the economic impacts of Eyjaf? 4

A
  1. Plane companies loss of £130 million per day.
  2. Thomson claims to lose £5-6 million per day.
  3. Limited food source – export spending will increase – less money for preparation.
  4. Cattle died – contamination of water.
28
Q

What were the environmental impacts of Eyjaf?

A
  1. Photosynthesis reduction – plants died.
  2. 10,000+ tonnes of carbon.
  3. Contamination of water – high levels of fluoride.
  4. Flash flooding.
  5. Many thunderstorms, gas emissions and lava flows following the eruption.
29
Q

What were the secondary MEDC global impacts regarding Eyjaf? 5

A
  1. Aircraft ban – Britain had anticlyonic weather - ash cloud was dispersed better.
  2. 6 flightless days, 17,000 flights per day being cancelled (overall 95,000 cancelled flights).
  3. $2 billion lost business overall.
  4. Shares in Air Travel fell 4% - less fuel was needed, loss of money in the oil industry.
  5. London lost £102 million of tourist income – knock on effect.
30
Q

What were the secondary LEDC global impacts regarding Eyjaf?

A

20% of the Kenyan economy is based on the export of green vegetables/cut flowers to Europe (perishable goods).
Flight ban - products returned unsold/destroyed.
1 million flower stalks were unsold in the first 2 days.
50,000 farmers were temporarily unemployed as beans/peas couldn’t be sold.

31
Q

How vulnerable were those near Eyjaf?

A

The volcano is known to have erupted 5 times.
In March there were warning signs of an eruption - 3,000+ recorded earthquakes, (most being less than 2 on the Richter scale).

32
Q

What was LOCAL Eyjaf preparation like?

A

First March small eruption - gave time to prepare.
Good warning system – texts sent out 30 minutes prior eruption.
Emergency services were well prepared.

33
Q

What was GLOBAL Eyjaf preparation like?

A

IMO - provides warnings, weather radar - able to calculate ash distribution.
24/7 watch - meteorologist is present, seismologist and hydrologist are on call.
IMO worked closely with British Meteorological Office.
Tracked/prepared for.
Ash cloud - tracked by satellite by many nations.
All European countries - bodies which determine the safety of conditions to fly in – greater capacity to cope - able to arrange alternatives.
EU is well prepared – self-sufficient.
Other transport systems e.g. Channel tunnel.
Legally well prepared – stuck travellers were entitled to legal compensation from their airlines.
Airlines - legally responsible for the well-being of stuck passengers.
EU’s insurance system - people/companies able to claim back any losses.
Companies had contingency plans in place e.g. Tesco flew Kenyan produce into Spain and then using road haulage.

34
Q

What was the overall response to Eyjaf like?

A

DOMESTIC RESPONSE – unlike LEDCS.
Many countries had responded by themselves/collectively - greater coping capacity.
Legal, technical and infrastructure systems can cope with hazards and economic impacts.
Mitigated deaths.

35
Q

Where is Mount Nyiragongo located?

A

Virunga Montains, Congo.

Associated with the African rift valley – perhaps a hot spot.

36
Q

What are the volcanic characteristics of Nyiragongo?

A

Main crater – 250m deep, 2km wide.
Stratovolcano.
Lava lake – very fluid - basaltic – fast flowing e.g. 90km.
Together with neighbouring volcano - responsible for 40% of Africa’s volcanic eruptions.

37
Q

What was the eruption of Nyiragongo like?

A

Months of increased seismic activity and fumaroles.
Unexpected eruption in January 2002 – opened a fissure 13km long.
Spewed lava 2km deep.
Flowed in the direction of Goma and Lake Kivu.
Lava warnings - allowed time for evacuation.

38
Q

What were the SOCIAL impacts of Nyiragongo? 6

A
  1. 150 died.
  2. 350,000 evacuated – mainly to Rwanda. Caused a problem providing food/shelter.
  3. 120,000 homeless.
  4. Thousands need medical attention – smoke effects/water-bourne diseases e.g. dysentery.
  5. Looting from abandoned buildings.
  6. Lava flows destroyed 1/3 of Goma (population - 200,000).
39
Q

What were the ECONOMIC impacts of Nyiragongo? 5

A
  1. Commercial centre destroyed – 3 health centres and 1 hospital.
  2. Lava covered runway at Goma airport.
  3. UN total aid cost was $15 million.
  4. Several earthquakes - structural building damage.
  5. Mass unemployment increase.
40
Q

What were the ENVIRONMENTAL impacts of Nyiragongo? 2

A
  1. Sulphurous lava in Lake Kivu - contaminated water.

2. Temperature fear - would allow toxic gases to be released from lake bed.

41
Q

What was the reaction to the eruption of Nyiragongo like?

A

‘Red Alert’ for Goma – initial response. Allowed full evacuation to take place (low death toll).
2 days afterwards, UN brought in humanitarian aid e.g. biscuits, then substantial food e.g. maize.
UN - set up camps.
High costs in restoring Goma.

42
Q

Where is Mount Etna located?

A

Sicily, Italy - RICH.
25% population live on the flanks – fertile volcanic soils.
Destructive plate margin.
African plate subducts under the Eurasian plate.

43
Q

What are the volcanic characteristics of Etna?

A 
Stratovolcano.
Small calderas present.
3 prominent craters.
Lots of vents on the side of the volcano from where lava emerges – cinder cones formed.
Not particularly dangerous.
44
Q

What was the nature of the Etna eruption?

A

December 1991 – 1993.
Acidic lava - low effusive rate.
Lava flowed down the SE flank into the Valle del Bove.

45
Q

What were the SOCIAL impacts of Etna? 3

A
  1. 0 deaths.
  2. Lava destroyed springs.
  3. Several lost homes/farms in the Valle del Bove – slow reactions.
46
Q

What were the ECONOMIC/ENVIRONMENTAL impacts of Etna? 2

A
  1. Total cost - millions.

2. Vineyards/chestnut orchids destroyed.

47
Q

What protective measures were put in place to limit Etna lava flows? 4

A
  1. Large earth barrier – 400m long across the southern end of Valle del Bove.
    Held back the lava for months.
  2. Smaller barriers overwhelmed – accumulated lava began to spill over – orchards ruined.
  3. Dropping concrete blocks from helicopters into the roof of the upper lava tube.
  4. 1992 – blasted openings – diverted the flow.
    Stopped advancing on Zafferana.
    Eruption ended in 1993.
48
Q

How successful were the Etna protective measures and why?

A

Successful due to:
Low effusion rates during eruption.
High elevation of eruptive vents – 2,250m in altitude and well away from populated areas.
Possibility of diverting the lava flow into unpopulated areas (at least 7km from the nearest village).

49
Q

What were the long term responses to Etna?

A

INGV - improved monitoring.
Measures randon gas.
GPS - slope changes.
Highly sensitive seismometers.

50
Q

Can lava flows always be stopped?

A

Mount Etna 2002 – lava flows destroyed ski station. Clouds of ash rained down, affecting Catania.

A Level Geography - Plate tectonics and associated hazards (14 decks)

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