Geography Unit 1 Restless Earth

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Inside the Earth:

The inside of the earth is made up of many layers; the crust is a layer of rock and is the surface of the earth, then comes the upper mantle followed by the lower mantle, then the outer core and finally the inner core. 

The crust makes up the lithosphere and is split into tectonic plates which move very slowly on a layer called the asthenosphere. There are two types of crust:

- continental crust forms the land

- oceanic crust under the oceans

Inside the earth it is very hot we know this because of molten lava from volcanoes and hot springs. The inner core is so deep and under such pressure that it stays solid whereas the outer core is under less pressure so is a liquid. As heat rises from the core it creates convection currents in the mantle, these are strong enough to move tectonic plates on the earths surface. 

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Plate Tectonics:

Pangea was formed millions of years ago when all the continents were joined together. Today the earths lithosphere is split into 15 tectonic plates that slowly move on the asthenosphere. Where 2 plates meet is called the plate boundary, this is where most volcanoes and earthquakes occur. There are 4 main types:

- constructive plate boundaries are formed when two plates move apart

- destructive plate boundaries are formed when one plate is pulled under the other

- conservative plate boundaries are formed when two plates slide past each other

- collision plate boundaries are formed when two plates move towards each other

New oceanic crust forms constanly at plate boundaries, convection currents bring magma up from the mantle which is injected between the seperating plates. As the magma cools it forms new oceanic crust. 

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Developed World - Iceland 2010:

The volcano was on a constructive plate boundary it was predicted to erupt so 500 people were evacuated from the area however the volcanic eruption threw tonnes of volcanic ash into the air which formed an ash cloud. This ash cloud meant no aircrafts could fly meaning airspace closed for 6 days. 

Developing World - Mount Nyiragongo 2002:

The volcano spilled out a river of lava 1000 meters wide and 20km long, destroying 14 villages. 100 people died, 12500 homes were destroyed but luckily the eruption was predicted and 400,000 people were evacutaed. The UN sent 260 tonnes of food and governments around the world gave $35 million to pay for aid. 

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Developed World - New Zealand 2011:

The earthquake was a magnitude of 6.3 on the richter scale and the damage cost £1.9 billion. 65 people died and 30 were trapped under rubble and collapsed buildings. People were immediately evacuated to safe places and the emergency services including the army were called to help resue people trapped and injured. 

Developing World - Haiti 2010:

The earthquake measured 7.0 on the richter scale. The primary effects were the presidential palace and many other buildings collapsed, 230,000 people were killed because they dont have emergency services like in the developing world. The earthquake was shortly followed by two aftershocks causing more devestation. Help came from around the world including charities sending relief teams and celebrities raising awareness in order to raise money. 

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Predicting Volcanoes:

Scientists have the technology to predict when a volcano will erupt. These technologies include:

- aircrafts to measure the amount of gas given off by the volcano

- tiltmeters detect when a volcano swells up and fills with magma

- boreholes measure the temperature as magma heats up

- hot springs are monitored

- concrete shelters protect against volcanic bombs and ash

- seisometers monitor earthquakes which increase before a volcanic eruption

- concrete lahar channels divert dangerous mudflows

- evacuation routes are signposted and evacuation drills happen regularly

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