Tectonics Case Studies

Tectonic case studies for AQA Geography A2 unit 3

  • Created by: Ella
  • Created on: 05-05-13 15:49

Mt. Etna

- July 2001
- Europe's highest and most active volcano
- On a convergent plate boundary (Eurasian = SIAL, African = SIMA)
- Strombolian/ volcanian volcano
- It is a decade volcano. The Decade Volcanoes are 16 volcanoes identified by the (IAVCEI) as being worthy of particular study in light of their history of large, destructive eruptions and proximity to populated areas
- 25% of Sicily's population lives on Etna's slopes
- 0 deaths   - There were hundreds of small magmatic earthquakes
- Had seismometers to help detect the earthquake, could link to low death toll
- Earth dams 400m long and channelising and diverting lava flows
- Italy gave £5.6 m in aid  - Tourism used for income
- Tax breaks for villagers  - Evacuation plans
- Holiday villas destroyed
- Airport forced to close (29th July)
- Zafferena wiped out

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Nevado Del Ruiz

- November 13th 1985
- Recurrence interval of 160 - 400 years
- On the Pacific Ring Of Fire and most Northern of the Andean volcanic belt
- Peleian/ Plinian -Rhyolitic lava
- Nazca (SIMA) and South American (SIAL) plates

- 23000 dead (only pop of 29000)
- £1bn damage - Town of Armero erased

- Appeal for aid was too late - 1 of the 2 access roads were blocked.
- No evacuation  - Severe weather the day before
Deadliest lahar in recorded history
- 2nd deadliest disaster of the 20th century
- High sulphur content, magmatic earthquakes, fumaroles that spewed steam gave an indication it may erupt. However many of these warnings were ignored.

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Haiti Vs Christchurch NZ

Focus -         13km                       5 km
Boundary-      Transform                 Transform
Epicentre-      Port- au Prince         Christchurch
Plates-          Caribbean and N American Pacific and Indo-Australian
Deaths-         230,000                    181-185
Injured-          300,000                    46
Mag-              7                              7.1 and 6.3
HDI-               0.454                        0.908
GDP(pc)-        $1300                        $28,000
Management- Little, gov building collapsed Cabinet meeting that day

Haiti- Worst earthquake in 200 years, death toll so high because of lots of slums, happened on steep land causing avalanches, 500,000 homeless, prison destroyed- 4000 inmates escaped, electricity supplies damaged, hospitals destroyed, cholera outbreak due to poor sanitation, humdity meant that bodies decayed quickly, 1 in 5 jobs lost, politically unstable, due to lack of machinary- finds it difficult to produce its own food.
NZ- High frequency of earthquakes but often low magnitude, although many buildings were aseismic- many had already been shaken, offers of aid immediately (Australia), 180 police, liquidfaction, happened at 12:50 - many out and about/ at work.

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Hawaii Mauna Loa Hotspot

- Sits on the Pacific plate
- The world's most active volcano
- Shield volcano
- The magma plume stays in the same place but the crust above it moves. This has made the chain of volcanoes in Hawaii. The further-away from the magma plume, the older and less active the volcano should be. Mauna Loa is one of the newest ones.
- Has basaltic lava which makes it runny and not as explosive
- It also erupts consistently and is a great threat to property.
- in 1990, an eruption created a lava field which consumed almost the whole town of Kalapana in East Hawaii
- In 1990, the USGS made a map which identifies areas of highest risks and monitors the way that the site is used and that walkers do not stray into dangerous areas
- The hazards of Hawaiian volcanoes include: lava flow, tephra, volcanic gas, explosive eruptions, ground cracks and settling
- The town of Hilo is expanding, as the demand for land increases, it gets closer to the volcanic field which could lead to later issues

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Tokyo Sky Tree - Building techniques

- 634m tall
- Made of steel, concrete and steel-reinforced concrete
- Has an equilateral triangular base with deep roots
- Reinforced concrete centre is structurally separate

Made of strong materials with deep foundations to absorb energy. Strengthened to keep with construction laws.

Buildings to withstand tsunamis also often have open foundations or concrete tsunami walls.

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Boxing Day Tsunami

- On a convergent plate boundary on a blind thrust fault. Involves the Eurasian, Indo-Australian and Burmese Micro plates.
- Had a magnitude 9 (4th largest earthquake of recent times)
- Fault line was the Sunda trench which is 250km off the Sumatra coastline
- Was up to 115m high
- Low frequency margin (no activity for 200 years)
- Indonesia- Closest so took only 10 mins to get there. Affected as many were subsistence fishers so many lived on the coast
- Sri-Lanka- Suffered more than anywhere else
- Maldives- Of 199 islands, 20 were said to be completed destroyed
- 275,000 killed over 14 countries and 2 continents
- 141,000 houses destroyed
- US $9,9 billion estimated damage
- Us $14 billion in international aid

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Isle Of Arran - Intrusive landforms

Intrusive landforms are formed beneath the Earth's surface and is caused by the movement of magma into spaces in rock strata. Magma then cools and hardens and is then exposed though weathering and erosion of less resistant rock surrounding it.

- Dyke- formed across the bedding planes. e.g Glen Sannox (Witches Step)
- Sill - Formed parallel to the bedding plane e.g Hills of Southern Arran
- Batholith- General doming deep below the ground e.g Northern Hills of Arran
- Laccolith- Lens shape. Overlying rock strata arching upwards. Formed at shallow depths.

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