Geography - Restless Earth

The earth

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The Earths structure

The earth is separated into 4 sections.

1. The inner Core- the core is made out of solid iron and nickel.

2. The outer core - the same as outer core

3. Mantle - the mantle is a semi molten roak taht moves really slowly

4. Crust - divided into lots of slabs called tectonic plates.

Plates are divided into 2 types

1. Continental crust - thicker and less dense

2. Oceanic crust - thinner and more dense

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Plate margins

There are three types of plate margins.

1. Destructive - this is when two plate margins are moving towards each other

2. Constructive - this is when two plates are moving away from each other

3. Conservative - this Is when two plates are moving sideways Past each other

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Fold mountains

Fold mountains are formed when two plates collide at destructive margins.

When tectonics plates collide the sedimentary rocks are folded and forced upwards to form mountains.

Fold mountains are found in destructive margins.

You get fold mountains when a continental and oceanic plate collide.

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Humans use fold mountains for lots of things

Farming - higher slopes used for grazing animals e.g. Goats and lower slopes used to grow crops.

Mining - used for metal ores. Steep slopes makes mining difficult so zig zag roads have been carved out on the sides to get to them.

Tourism - fold mountains have spectacular sceneries which attract tourists. Tourists do sports like snowboarding, skiing etc...

Hydro electric power - steep sided mountains and high lakes ( to store water ) makes fold mountains ideal for generating hydro electric power.

Forestry - used to grow trees to use for fuel, building materials and to make things like paper and furniture.

The alps is a fold mountain range

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Earthquakes are caused by the tension that builds up at all three types of plate margins.

Destructive margins - tension builds up when one plate gets stuck as it is moving down past the other into the mantle.

Constructive margins - tension builds along cracks within the plates as they move away from each other.

Conservative margins - tension builds up when plates that are grinding past each other get stuck.

The plates jerk past each other causing shockwaves.

The shockwaves is the earthquake.

The waves spread out from the focus - the point in the earth where the earthquake

starts. The focus is where the waves are stronger and more dangerous.

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Earthquakes can be measured

The richter scale - measures the amount of energy released by an earthquake called the magnitude.

Magnitude is measured using the seismometer.

Major earthquakes are above 5 magnitude.

Another scale is called the Mercalli scale.

This measures the effects of the earthquake.

Effects are measured in eye witnesses for observatione of what happened. Can be in form of photos or words.

It's a scale of 1 to 12

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Impacts of earthquakes

Earthquakes have primary and secondary impacts.

The primary impacts is the immediate effects.

The secondary impacts are the Effects that happen later on.

Primary impacts - buildings and bridges collapsing, people are injured or killed, roads or airports are damaged, electteicity cables are damaged, gas pipes are broken.

Secondary impacts - earthquakes can trigger landslides and tsunamis, leaking gas, people are left homeless, shortage of water and lack of proper sanitation, roads are blocked or destroyed, businesses are damaged or destroyed causing unemployment.

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Impacts on poorer countries

Earthquakes are more severe in poorer countries because of low quality housing, healthcare, not much money.

People still continue to live in areas where earthquakes have happened because:

Always lived there

Employed in the area

Confident of support from the government

Severe earthquakes won't happen again in that area

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Reducing the impacts of earthquakes

You could reduce the impacts of earthquakes by:

1. Prediction - clues like lots of small tremors, crack appearing in rocks and strange animal behavior.

2. Building techniques - buildings can be designed to withstand earthquakes by using stronger materials like reinforced concrete or building special foundations that absorb the shockwave.

3. Planning - future developments e.g. New shopping centres can be built away from areas that are more at risk from earthquakes.

Government can plan evacuation routes to get people out of dangerous areas quickly and safely after an earthquake.

Emergency services can train and prepare for disasters e.g. Practicing rescuing people from fallen buildings.

Education - people can get educated in what to do when there is an earthquake.

Aid - people that have been affected receives aid from the government.

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Rich and poor parts are effected differently

The effects of earthquakes and the responses to them are different in different parts of the world. A lot depends in how wealthy the par of the world is.

Rich country - Italy in 2009 the size of it was 6.3 on the richter scale, cause was movement along a crack in the plate at a destructive margin. Damage was $15 billion

Poor country - Pakistan in 2005 the size was 7.6 on the richter scale, cause was the movement along a crack in the plate at a destructive margin. Damage was $5 billion.

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Volcanoes are found at destructive and constructive plate margins.

1.At destructive plate margins the oceanic plate goes under the continental plate because it is more dense.

A volcano is formed when the oceanic plate goes down into the mantle then it's melted and destroyed. Pool of magma is formed. The magma rises through cracks in the crust called vents.

2. At constructive margins thebl magma rises into gaps created by the plates moving apart.

3. Some volcanoes are also form over parts of he mantle that are really hot called hotspots e.g. Hawaii

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Different types if volcanoes

There are three three types of volcanoes.

1. Composite volcanoes - made of ash and lava that's erupted cooled and hardened into layers. Lava is usually thick and slow. Hardens quickly to form a steep sided volcano.

2. Shield volcanoes - made up of lava. It is runny, flows quickly and spreads over a wide area, forming a low, flat volcano.

3. Dome volcanoes -nmade up of lava. It is thick, flows slowly and hardens quickly, forming a steep sided volcano.

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Impacts of volcanoes

People live near volcanoes because the soil is fertile because of volcanic ash and lava this makes it good for growing crops which attracts framers, Volcanoes are also tourist attractions and volcanoes are a source of geothermal energy which Canberra used to generate electricity.

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Volcanoes primary and secondary impacts

Primary effects are the immediate effects of a volcano e.g. Lava, pyroclastic flows, buildings collapse if enough ash falls on them, people and animals are injured or killed, crops are damaged and water supplies are contaminated when ash falls on them, people and animals are suffocated by carbon dioxide.

Secondary impacts is what happens later on e.g. Fires are started by lava flows and pyroclastic flows which then spread, people are left homeless, shortage of food and water, roads are blocked or destroyed.

Impacts are more severe in poorer countries instead of richer countries.

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Reducing the impacts of volcanoes

1. Prediction - scientists can monitor the tell tale signs that come before a volcanic eruption. Things such as tiny earthquakes, escaping gas and changes in the shape of the volcano means an eruption is likely to happen.
2. Planning - future developments can be built To avoid the areas most at risk, emergency services can train and prepare for volcanic eruptions.
3. Building techniques - can be streghtened so they're less likely to collapse under the weight of the ash.
4. Education - Governments can education young people on how to evacuate safely when there is an eruption.
5. Aid - poorer countries that have been affected by a volcano eruption can receive aids from the government.

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