Geography Paper 1
- Created by: AM6200
- Created on: 30-04-16 14:55
Unstable Earth
Constructive plate margins - where plates are moving apart
Conservative plate margins - where plates slide past eachother
Destructive plate margins - where plates collide
Collision zones - type of destructive margin
Oceanic crust - under the oceans (thick)
Continental crust - under continents, land masses (thin)
As heat rises from the Earth's core, it sets off convection currents in the mantle which allows plates to move and is the movement that sets off earthquakes and volcanic erruptions.
Plate Margins
Constructive
At constructive plate margins two plates move apart; like the North American and Eurasian plates move apart in Iceland (Volcano Eyjafjallajokull). It allows magma from the mantle to rise up to the Earth's surface and make or construct new crust. Earthquakes can also be caused by friction of the plates as they move over the mantle
Destructive
This is wear a oceanic and continental plate collide and as the oceanic is denser than the continental plate, the continental plate sinks beneath into the mantle. When its sunk in the mantle it melts forming magma. It also takes sea water down with it making it less dense in the mantle. This will rise up through the continental crust and explode as a volcanic eruption. The sea water turns into steam. The friction can also cause earthquakes
Conservative
As the plates move past eachother the friction between the plates causes earthquakes. These are rare but can be destructive if the earthquakes occur close to the earth's surface.
Landforms at plate margins
Fold Mountains They lie on a collision zone and the two continental plates are pushing againist eachother. As they are the same density neither sink, so they push upwards forming fold mountains
Ocean Trenches
Ocean trenches are also found on destructive plate margins as the denser plate sinks below the continental plate it creates a deep-sea trench
Composite Volcanoes Found at destructive plate margins, when the oceanic plate sinks into the mantle and melts with the sea water, then rises up through the cracks in the earth's crust forming volcanoes. Eruptions are violent, they are also layered of ash and lava with a tall cone shape
Shield Volcanoes
Found at constructive plate margins as the plates move apart the magma rises up from the mantle, these are non-violent erruptions and have a wide base and gently sloping sides
Using Fold Mountains - The Alps
Located in Central Europe covering Austria, Italy, Switzerland, Germany & France Created when the African plate collided with the Eurasian plate
Uses:
Farmers farm cattle on the valley floors and goats on the steep edge of the mountains, they also have vineyards on the sunny side of the mountains to bring money to the economy
Tourism is a popular use of the Alps with winter sports e.g. skiing and also having locals and visitors supporting the tourism industry, giving an income to the locals. In summer they offer walking and climbing of the mountains
Energy companies use the steep terrain and build dams across valleys to provide 60% of Switzerlands power through HEP
Trees are chopped down for the lodges for tourism meaning they have access to cheaper materials
Using Fold Mountains - The Alps 2
How have people adapted?
Farmers adapted their practise to working in fold mountains by placing goats on steep terrain and moving cows in the summer up to the peaks of the mountains, producing local goods sold to tourists leading to a higher income
A larger use of the alps has led to infrastructure being improved making it easier to access the alps so people can live and work more effectively. They have placed ski lifts and cable cars to move people and cattle
Tourism has developed as locals developed new ways of activities for the resort throughout summer as well as winter providing jobs for locals
Energy companies placing dams has led to people using renewable energy resources instead of scarce non-renewable resources
The industry use natural resources to provide wood for variety of uses. Also providing long term employment
Volcanic Eruption - Montserrat
Montserrat located in the Caribbean Islands This volcano is on a destructive plate margin meaning the oceanic plate sunk and was melted and the magma rised leading to a violent eruption
The effects
More than half of Montserrat became uninhabitable, infrastructure was destroyed including the airport, 19 people died and many people fled from the Island and tourism decreased
Immediate respones
Residents evacuated, population fell to 3500, British government spent money on aid - temporary buildings, charities set up temporary schools and sent emergency food for farm animals
Long term respones
People returned to the island as the population rised to 5000, the population structure changed as many young people left and didn't return and the British government spent £200 million to restore electricity, water and build infrastructure
Monitoring Volcanoes
How?
Checking changes in shape using electronic tilt meters and global positioning systems
Using seismometers to listen to the rumbling of the volcano as magma flows to the surface
Creating a seismology network to collect information
Measuring sulfur dioxide emissions
Supervolcanoes - Yellow Stone National Park, USA
How its formed
The magma is blocked from reaching the Earth's surface, the pressure begins to build up, more rock melts and more magma is formed. When the pressure becomes to much the entire surface above the magma chamber is blown away by a huge explosion, forming a caldera
Impacts of an eruption
Magma would be flung 50km into the atmosphere
All life 1000km away or nearer would be killed by falling ash, lava and the force of the explosion
Enough ash would flow out of the volcano to cover the whole of the USA leading to a mini ice age as radiation from the sun would be unable to reach
This means
Crops wouldn't grow, people would starve, economies would collapse and society would not survive
Earthquake
Features of an Earthquake
When an earthquake occurs the ground shakes violently causing infrastructure and buildings to collapse
This happens when the plates have been stuck and eventually move sending out huge pulses of energy causing shock waves to travel out from the focus (where the earthquake starts) to the epicentre which is the point on the earths surface directly above the focus
Measuring Earthquakes
The Richter Scale
The magnitude of an earthquake is measured. There is no upper limit to this scale
The Mercalli Scale
The scale goes from 1-12 and measures power and effects of an earthquake based on observation
Chile, 2010
Occured at a destructive plate margin, the magnitude being 8.8
Primary effects
500 killed & 12,000 injured
500,000 buildings damaged
Infrastructure damaged & Airport slightly damaged
Secondary effects
Most of Chile lost power
Water and communications
Fire brokeout at a chemical plant
Chile's copper mines suffered damage - crucial to their economy
Haiti, 2010
Occured on a destructive plate margin with a magnitude of 7.0
Primary effects
220,000 dead & 300,000 injured
Infrastructure destroyed including the main port
200,000 homes damaged in Port-au-Prince and 1.3 million Haitians left homeless
Secondary effects
2 million Haitians were left without food and water
There were many dead bodies in the street leading to disease - Cholera
Destruction to government buildings meaning the police force collapsed - increased crime
Infrastructure damaged, no aid could get through
Chile, 2010 - Responses
Immediate respones
In hours floating bridges were arriving from specific countries as the presidents requests for help
The day after the quake route 5 was temporarily repaired so aid could arrive to places
10 days after the earthquake 90% of homes had power and water restored
$60 million was raised to build emergency supplies and shelter (from a national telethon)
Long term responses
A month after the earthquake Chile's government launched a housing reconstruction plan to build 196,000 homes
The huge copper reserves earned plenty of money for the reconstruction so did not have to rely on foreign aid
Haiti, 2010 - Respones
Immediate responses
Aid was slow to arrive due to infrastructure being damaged
American engineers tried to clear debris at port for aid to get in
The USA sent ships, helicopters and $100 million in aid
The food aid cluster was set up to feed 2 million
Field hospitals were set up
Long term responses
New homes still need to be built
Haiti is dependent on Overseas aid to recover
Haiti is still not back to the way it used to be
Haiti & Chile - Prediction, Prepare & Protection
Prediction - Set up tilt meters to see the plate movement
Preparation & Protection (Chile)
Buildings to withstand earthquakes
Earthquake plan was set up in 2002
Government sets up anti-disaster drills
All Chileans know if an earthquake occurs they must 'Drop, Cover, Hold' under a heavy table or doorframe
Preparation & Protection (Haiti)
Haiti weren't prepared as they hadn't had an earthquake in living memory
They had a weak government and little money (poorest country in world)
The homes were not built to withstand earthquakes as they were poorly built and overcrowdered
Tsunami - Indian Ocean, 2004
A tsunami that occurs in the sea displacing water towards land
The boxing day scored between 9.0 and 9.3 on the Richter scale
Effects
289,601 were killed or are missing & 400,000 people lost their jobs
Homes, crops and fishing boats were destroyed & tourist resorts were hit
Immediate Respones
Clean water, food and tents arrived as aid& $7 billion was donated for the affected countries
The UN's World Food Programme provided food aid for 1.3 million people
Long term responses
There are tsunami warning systems, drills and the countries are restoring mangroves to absorb water and the wave power before it hits civilians
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