Hostile Earth (Part 1)

In this mini-series we’ll be exploring the destructive side of the Earth, its effects and how we can help to protect ourselves. (This will also cover everything you need to know for Unit 2 of  AQA GCSE Geography!)

Plate Margins

Conservative

  • 2 plates slide past each other, travelling in opposite directions
  • Activity: violent earthquakes
  • Example: San Andreas Fault in California (Pacific & North American plates)

Destructive

  • An oceanic plate moves towards a continental plate, but because it is heavier it sinks and is destroyed, forming deep-sea trenches  and island arcs. Volcanoes also form as the extra magma created from the destroyed oceanic plate is under pressure and is forced upwards through the rock.
  • Activity: violent volcanic & violent earthquakes
  • Example: Chile (Nazca & South American plates)

Constructive (aka Sea-Floor Spreading)

  • 2 plates move apart forming new oceanic crust as well as mid-ocean ridges with volcanoes
  • Activity: gentle volcanic and gentle earthquakes
  • Example: Mid-Atlantic Ridge (e.g. Iceland) (North American & Eurasian plates)

Collision

  • 2 continental crusts collide and as neither can sink they are forced upwards, creating fold mountains
  • Activity: violent earthquakes
  • Example: The Himilayas (Eurasian & Indo-Australian plates)

MEDC Case Study – Kobe, Japan

  • Plate Margin: Destructive
  • Plates: Eurasian & Phillipenes
  • Location: Urban
  • Local Date & Time: 17th January 1995 05:46 a.m.
  • Magnitude: 7.2
  • Primary effects: 200,000 buildings collapsed, 3/4 all quays destroyed, 10 bridges along the bullet train route collapsed, 1 km of Hanshin highway collapsed
  • Secondary effects: 5,500 dead, 40,000 injured, 230,000 homeless when temps averaged -2 degrees, fires from ruptured gas/electricity mains, grid-locked roads, lack of water supplies, industries shut down

LEDC Case Study – Sichuan, China

  • Plate Margin: Conservative
  • Plates: Eurasian & Indo-Australian
  • Location: Rural
  • Local Date & Time: 12th May 2008 02:30 p.m.  
  • Magnitude: 7.9
  • Primary effects: 7,000 classrooms and most buildings collapsed, communication (e.g. phone lines) destroyed, landslides, hospitals destroyed
  • Secondary effects: 70,000 dead, 40,000 injured, 4.8 million homeless, 70% roads blocked, 46 million affected in total, 18,000 still missing presumed dead, $86 billion damage, isolation of villages in remote areas

Reducing the risks from earthquakes

Key definitions

  • Prediction: the use of science/technology to monitor techtonic activity
  • Preparation: creating emergency plans to implement once the disaster has struck
  • Planning: e.g. building design – earthquake-proofing buildings in urban areas to reduce damage, injuries & death
  • Retrofitting: addition of new technology to older buildings
  • Appropriate technology: technology designed with consideration of intended community

In an MEDC…

  • Computer controlled counterweight on roof
  • Cross-bracing to add strength and prevent twisting
  • Automatic window shutters stopping shattered glass#
  • Automatic sprinklers to prevent fires

In an LEDC…

  • Roof made of reinforced concrete
  • Hollow concrete bricks which cause less damage if they fall
  • Foundations made mainly of stone from the remains of previously destroyed buildings
  • Relatively cheap and uses recycled materials

Special Case: Costa Rica

  • Bamboo homes – bamboo is strong but also flexible so less likely buildings will collapse. More environmentally friendly as only 70 hectares of land needed to build 1000 homes compared to 600 hectares of forest.

How to prepare your home:

  • Secure heavy, moveable items of furniture
  • Prepare an earthquake kit
  • Practice earthquake drills (e.g. Disaster Prevention Day in Japan)
  • After the shaking stops check for injuries and check the radio for further instructions
  • Building codes – homes built in at-risk areas must have strong earthquake-proofing

Preperation for and Response to Earthquakes..

MEDC

  • Local services are well trained and regularly have practice drills
  • New buildings comply with strict earthquake planning regulations
  • Emergency earthquake kits packed
  • Education – teach people what to expect in the event of an earthquake
  • Counselling for distressed children
  • Viible identification numbers on roofs to help helicopters assess damage

LEDC

  • Looks to international aid and world-wide charities for help
  • Cremate the dead to prevent disease
  • Airfields that bring in rescue teams and emergency supplies are often too far away
  • Poorly built buildings
  • Limited supplies for a large number of victims
  • Makeshift open-air hospitals
  • Limited funds to cover cost of supplies and rebuilding projects
  • Lack of radio/tv/internet that could communicate with people to allow time to evacuatedanger zones or help manage relief operations

Both

  • Evacuation centres in safe areas
  • Community ready and willing to search for victims/survivors but lacks the appropriate equipment
  • Monitoring movementss in the Earth’s crust
  • Massive disruption to power lines transport and communications
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Urbanisation in an LEDC – Rio de Janeiro

With reference to an example of an LEDC you have studied, explain why urbanisation is occurring and describe the effects upon the urban area.

Rio de Janeiro is a fast growing Mega-City, located around the natural harbour of Guanabara Bay, in south-east Brazil. It replaced Brasilia as the capital, and Sao Paulo as the largest city as well as centre of industry and commerce. The population of it’s urban area is around 12 million people. It is a city with two sides, that of the famous beaches of Copacabana and Impanema surrounded by luxury housing, and the problems of rapid urban growth. 

The urbanisation of the area of Rio has been mainly caused by the poor living conditions of many Brazilians, who live in the Catinga region of East Brazil. Those who live there face harsh conditions, where there is often drought on the land, with very little annual rainfall, and little vegetation. Many harvests fail, and when this happens they have to live on whatever scraps they have, sometimes only one small meal a day. With a poor, or even no water supply, illness and death is common, and the area has a very high infant mortality rate. The sad truth is they cannot afford doctors or medication, as they have such a poor wage, and many living along one of the rivers were forced to move and lost what little they had because a major company wanted to build a dam.

Many of these people choose to seek a better quality of life, and choose Rio. This is because they may have heard about it on the radio, and the fact that it is a big city, with better conditions, the opportunity of better wages, water supplies and amenities is very attractive.  

Now, due to a continual influx of people looking for a better way of life, Rio has some major issues to content with. One of the biggest problems the city faces is that of housing.  There are around ½ a million homeless street dwellers, with a million living in favelas, and another million people living in poor quality housing from the local authorities. There are over 600 favelas in and around Rio, the largest of which are Rocina and Morro de Alemao, both containing over 100,000 people. The homes are constructed with anything available including wood, corrugated iron and broken bricks or tiles, so are very poor in some cases in terms of staying at the right temperature or being completely waterproof if not enough material is available. They are built on hillside considered too steep for normal housing, as it is too dangerous to build there according to local building authorities. Homes built near the bottom, although a better site, can sometimes receive sewage running down the hillside in open drains. People near the hilltops however, must bring all their supplies they need from the bottom, including buckets of water several times a day.  Flash floods or landslides after heavy rainfall can easily cause less well built homes to be carried away, and home falling down from the top can damage or destroy many homes along the way down to the bottom, and 200 people died because of this in 1988.

Although several attempts have been made to clear the favelas, they are still there, as evicted residents, who did not receive new replacement housing (which was often little better than the original shacks), simply returned and rebuilt their homes. The local authority now accepts the presence of favelas and is working with resident association to improve the living conditions there.

Another problem Rio now faces is that of crime. Despite claims by residents that crime amongst the favelas has decreased, and that community spirit is increasing, non-residents perceive the area as somewhere to associate with organised crime, violence and drug trafficking. Rio de Janeiro has a worldwide notoriety for its use of drugs, in particular cocaine, and so well of residents are moving out of the City to places such as Barra da Tijuca, which they see as safer environments for their families.  The problem is seen as so bad, that tourists to Rio’s beaches, such as Copacabana, are warned not to take any valuables with them, and are advised not to wear jewellery or watches.

Traffic has also now become a major issue, as the geographical location of Rio means that the city is hemmed in between the mountains and the South Atlantic Ocean. This means that traffic is channelled down a limited number of routes, so for much of the day there is severe congestion, pollution and noise even through the night.

The final big problem is pollution. Due to the size of the city, huge amounts waste and rubbish is produced. In favelas this is unlikely to be collected, and its presence, together with possibly polluted water supplies and sewage in open drain causes serious health hazards. An example of this was the outbreak of Cholera in 1992. As well as this, because of the amount of businesses and homes, there is an industrial haze, intensified by traffic fumes, often hanging over much of Guanabara Bay. Along the coast the beaches and sea are also polluted.

Urbanisation is taking place in Rio de Janeiro because of poor living conditions in other parts of Brazil, making the residents decide to move to a big city in the hope of a better standard of living, creating many problems such as housing, traffic crime and pollution for the city itself.