Geography - The Restless Earth

Anotações:

• Crust: -Very thin layer ranging between 6-70km in thickness -Solid rock -Cold rock Mantle: -Molten Rock/Lava -Temperature ranges from 1,300 - 5,000 degrees Celsius -Liquid but with a jam like consistency Outer Core: -Liquid Metal -Mostly Iron with some Nickel -Very high pressure and temperature Inner Core: -Solid metal due to the high pressure -Very dense -Mostly Iron and Nickel -Can reach temperatures of 5,000 degrees Celsius

Anotações:

• Due to radioactive decay, the centre of the Earth is very hot. This heat causes convection currents in the Earth Mantle, which causes the mantle to move. The crust is broken up into the different tectonic plates which move due to the mantle beneath them moving.  

1. Destuctive

   Anotações:

   • Destructive margins are where two plates are moving towards each other eg along the east coast of Japan. Where an oceanic plate meets a continental plate, the denser oceanic plate if forced down into the mantle and destroyed. This often creates volcanoes and ocean trenches (very deep sections of the ocean floor where the oceanic plate goes down) 
2. Conservative

   Anotações:

   • Conservative margins are where two plates are moving sideways past each other, or are moving in the same direction but at different speeds, eg along the west coast of the USA. Crust isn't created or destroyed.
3. Constructive

   Anotações:

   • Constructive margins are where two plates are moving away from each other at the mid-Atlantic ridge. Magma (molten rock) rises from the mantle to fill the gap and cools, creating new crust.
4. Collision

   Anotações:

   • Where two continental plates meet, the plates smash together, but no crust is destroyed. This often forms fold mountains 

Anotações:

• Fold mountains are found at destructive plate margins and places where there used to be destructive margins eg. the west coast of North America You also get fold mountains where continental plate and an oceanic plate collide eg. the Andes in South America You also get fold mountains where two continental plates collide eg the Himalayas in Asia

Anotações:

•  When tectonic plates collide the sedimentary rock that have built up between them are folded and forced upwards to form mountains  Fold mountain area have lots of very high mountains, which are very rocky with steep slopes. There's often snow and glaciers in the highest bits, and lakes in the valleys between the mountains.

1. Farming

   Anotações:

   • Higher mountain slopes aren't great for growing crops so they're used to graze animals eg mountain goats Lower slopes are used to grow crops. Steep slopes are sometimes terraced to make growing crops easier
2. Hydro-Electric Power

   Anotações:

   • Steep sided mountains with high lakes (to store water) make fold mountains ideal for generating hydro-electric power
3. Mining

   Anotações:

   • Fold mountains are a major source of metal ores, so there's a lot of mining going on. The steep slopes make access to the mine difficult, so zig-zag roads have been carved out on the sides of some mountains to get to them.
4. Forestry

   Anotações:

   • Fold mountain ranges are good environments to grow some type of tree (eg conifers). They're grown on the steep valley slopes are used for things like, fuel, building materials, and to make things like paper and furniture.
5. Tourism

   Anotações:

   • Fold mountains have spectacular scenery, which attracts tourism. In winter, people visit to do sports like skiing, snowboarding and ice climbing. In summer, walkers come to enjoy the scenery. Tunnels have been drilled through some fold mountains to make straight, fast roads. This improves communications for tourists and people who live in the area as it's quicker to get to places.

1. Problem

   Anotações:

   • -Fold mountains like the Alps tend to have low population densities.  -The high altitude and steep slopes make it difficult to build houses and communication links, and to locate industries -.Roads and railways need expensive tunnels, passes, avalanche shelters and hairpin bends.  -There is little flat land for farming and the use of machinery is difficult.  -The climate is also cold and wet with heavy snowfall and strong winds, especially at high altitudes. -The growing season is therefore short and travel can be difficult, especially in the winter  - Avalanches and rock falls can block roads. and some settlements and roads need avalanche protection measures, e.g. shelters, wooden fencing, wire cages.
2. Solutions

Anotações:

• 1) Earthquakes are caused by the tension that builds up at all 3 types of plate margin: -Destructive: tension builds up when one plate gets stuck as it's moving down past the other into the mantle -Constructive: tension builds along cracks within the plates as they move away from each other. -Conservative: tension builds up when plates that are grinding past each other get stuck. 2) The plate eventually jerk past each other, sending out shock waves (vibrations). These vibrations are the earthquake. 3) The shock waves spread out from the focus - the point in the Earth where the earthquake starts. Near the focus the waves are stronger and cause more damage. 4) The epicentre is the point on the Earth's surface straight above the focus. 5) Weak earthquakes happen quite often, but strong quakes are rare.

1. Richter

   Anotações:

   • 1) This measures the amount of energy released by an earthquake (called the magnitude) 2) Magnitude is measured using a seismometer - a machine with an arm that moves with the vibrations of the earth. 3) The Richter scale doesn't have an upper limit  and its logarithmic - this means that an earthquake with a magnitude of 5 is 10 times for powerful than one with a magnitude of 4. 4) Most people don't feel earthquakes of magnitude 1-2. Major earthquakes are above 5.
2. Mercalli

   Anotações:

   • 1) This measures the effects of an earthquake 2) Effects are measured by asking eye witnesses for observations of what happened. Observations can be in the form of words or photos 3) It's a scale from 1 to 12

1. Secondary

   Anotações:

   • -Landslides could further burry people and collapse buildings. -Fires in collapsed buildings -Diseases, such as cholera, can spread through infected water and kill further people. -
2. Primary

   Anotações:

   • -Deaths and injuries, especially due to collapsed buildings.-Buildings will be damaged and destroyed -People will be made homeless-Water and electricity may be lost, sewage or water pipes may burst -Roads and bridges may be damaged

1. Composite

   Anotações:

   • -They are made up of ash and lava that's erupted, cooled and hardened to form layers -The lava is usually thick and flows slowly. It hardens quickly to form steep sided volcanos
   • Fact-file  Shape: Tall cone with narrow base and steep sides How its formed: Its made of alternating layers of lava and ash Found at what type of plate margin: Usually destructive Source of magma: Melted oceanic crust Type of eruption: Violent explosions Frequency of eruptions: Very irregular with long dormant periods Material ejected: Explosive lava bombs, ash, gas and pyroclastic flows. Example: Mount Fuji, Japan
2. Shield

   Anotações:

   • Made up of lava only The lava is runny. It flows quickly and spreads over a wide area, forming a low, flat volcano.
   • Fact-fileShape: Cone with wide base and gentle slopesHow it is formed: Layers of runny lava with little ashFound at what margin: Mainly constructive Source of magma: Rises directly from the mantleType of eruption: Lava pours out with little violenceFrequency of eruption: Regular and frequent eruptions that are often gentleMaterial ejected: Mainly runny lava Example: Mauna Loa, Hawaii 

1. Primary

   Anotações:

   • -Large areas of land can be covered in volcanic material -Homes, work places, schools, hospitals, government buildings, airports and roads can all be destroyed -People can be killed -Whole areas of land can the flattened by pyroclastic flows -Vegetation and farmland can be lost
2. Secondary

   Anotações:

   • -Fires can further destroy buildings - People are made homeless -Business and tourism can suffer, affecting the economy - Food shortages due to destroyed crops and farmland -Volcanic ash can improve soil fertility

1. Immediate

   Anotações:

   • - People are evacuated from the area -Shelters set up for evacuees -Search and rescue teams set up to look for survivors -Money and Aid, such a food, water and blankets, sent from other countries
2. Long Term

   Anotações:

   • -Rebuilding of any damage -Reducing the effects of future eruptions

Anotações:

• 1) Health Benefits - Silica in geothermally heated pools can provide great skin benefits 2) Tourism - Volcanos are a source of interest for many people meaning people will visit them 3) Fertile Soil - Natural nutrients in volcanic ash can cause soil to grow good crops 4) Mineral Deposits - Precious stone can be formed in the volcanic lava 5) Building Materials - Volcanic rocks such as pumice are strong and can be used in buildings 6) Hot Water - Water can be pumped into the volcano to be heated which is the pumped straight into people homes  7) Geothermal Energy - Water can e pumped into the volcano which turns into steam to turn a turbine to generate energy.  

Anotações:

• A super volcano is a volcano on a much bigger scale and with much more devastating consequences. To be a supervolcano they usually admit at least 1000 cubic kilometres of material when they erupt and usually have craters over 30km wide. 1000 times bigger than Mt St Helens. There are 7 supervolcanos worldwide.

1. Yellowstone CASE STUDY
2. Impacts

   Anotações:

   • 1) A supervolcanic eruption will throw out thousands of cubic kilometres of rock, ash and lava (much more than normal volcanos, which usually produces a couple of cubic kilometres) 2) A thick cloud of super-heated gas and ash will flow at high speed from the volcano, killing, burning and burying everything it touches. Everything within tens of miles will be destroyed. 3)Ash will shoot kilometres into the air and block out almost all daylight over whole continents. This can trigger mini ice ages as less heat energy from the sun gets to Earth. 4) The ash will also settle over hundreds of squared kilometres, burying fields and building (ash from normal volcanos usually covers a couple od squraed kilometre
3. Formation

   Anotações:

   • Supervolcanos develop in a handful of places around the globe - at destructive margins or over parts of the mantle that are very hot (hotspots). How they form at hotspots (like Yellowstone): 1) Magma rises up through cracks in the crust to form a large magma basin below the surface. The pressure of the magma causes a circular bulge on the surface several kilometres wide. 2) The bulge eventually cracks, creating vents for lava to escape through. The lava erupts out of the vents causing earthquakes and sending up gigantic plumes of ash rock. 3) As the magma basin empties, the bulge is no longer supported so it collapses - spewing up more lava. 4) When the eruption's finished there's a big crater (called a caldera) left where the bulge collapsed. Sometimes these get filled with water to form a large lake
   • The characteristics of a supervolcano: -Flat (unlike normal volcanos, which are mountains) -Cover a large area (much bigger than normal volcanos) -Have a caldera (unlike normal volcanos where there's just a crater at the top) 

Anotações:

• 1) At destructive plate boundaries the oceanic plate goes under the continental plate because it is more dense (this also creates oceanic trenches): The oceanic plate moves down into the mantle, where it's melted and destroyed. A pool of magma forms. The magma rises through cracks in the crust called vents The magma erupts onto the surface (Where its called lava) forming a volcano.
• 2) At constructive margins the magma rises up into the gap, created by the plates moving apart, causing a volcano. 3) Some volcanos also form over parts of the mantle that are really hot (called hotspots) eg Hawaii

Anotações:

• Volcanos can be observed as active through tell tale signs such as Earth tremors, escaping gas, changes in the shape of the volcano and animals becoming stressed and leaving the area. There are many methods of monitoring volcanos such as: -tilt-meters (that record shifts in the ground), -seismometers (that relay shock wave data from the earth tremors), -analysing gases from the volcanic vents (this can give us information about the magma) -remote sensing using GPS (used to record changes to the volcanos form). Monitoring volcanos in this way can help to predict when and eruption may take place and the nature of this eruption. This can help decide what action, such as evacuation, need to be taken.

1. Economic
2. Environmental
3. Social