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22 Cards in this Set
- Front
- Back
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What are the parts of the earth? |
Inner core - Solid core due to pressure - 4000°+ Outer core - Made of Iron and Nickel - <4000° Mantle - Semi liquid layer - <3800° - 2800km Crust - Solid Rock - <100km |
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What is the crust of the earth like? |
Divided into 7 large and 12 small plates or hard rock floating on the hot mantle. These are either Oceanic or Continental. |
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What is the diference between Oceanic and Continental crust? |
Oceanic - between 5 & 10 km thick, heavier of the two, continually made and destroyed Continental - between 25 & 100km thick, lighter of the two, doesn't sink, nor is destroyed |
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Why do the plates move? |
Convection currents, which is hot rock rising in the mantle, pushes the plates around, known as continental drift, which, over the earth's 4.6 Billion history, has caused the continents to move far. |
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What are the 5 types of plate boundary plus anything else? |
- 1) Divergent (Constructive) - The plates are moving apart - Convergent (Destructive) - Plates moving together 2) Oceanic - Continental 3) Continental - Continental (Collision Margins) 4) Oceanic - Oceanic - 5) Transform (Conservative) - Plates slide past each other PLUS HOT SPOTS
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Describe what is happening at a divergent plate boundary and give an example. |
1) Two oceanic crusts are moving apart. 2) Hot Molten rock rises from the mantle through the gap the exists 3) This Molten rock is pushed to the sides, causing a ridge in the centre, pushing the plates apart 4) This Mid-Ocean ridge can become large enough that it emerges out of the ocean to form an island/Volcano, i.e Iceland E.g. Mid Atlantic Ridge |
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Describe what is happening at an Oceanic-Continental Convergent plate boundary and give an example. |
1) The heavier Oceanic crust bends and goes under the lighter continental plate, known as the subduction zone. This causes friction between the plates which causes earthquakes 2) This heavier crust goes into the mantle and melts. 3) This melted plate rises and settles under the continental plate, forming magma and lava 4) The Continental plate folds, forming mountains and volcanoes. 5) Over time, the magma builds up until it erupts as a volcano E.g. Pacific Ring of fire |
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Describe what is happening at a Continental-Continental convergent plate boundary and give an example. |
When two continental plates meet, neither subducts and the land between them is pushed up, forming NON VOLCANIC fold mountains. This large amount of friction however, DOES cause earthquakes. E.g. Indo-Australian/Eurasian Plate boundary |
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Describe what is happening at an Oceanic - Oceanic Convergent plate boundary and give an example. |
1) One of the two plates subducts beneath the other and is forced into the mantle. This causes friction between the plates which causes earthquakes 2) This plate is then melted and rises to the surface as magma. 3) Over time this magma escapes to form a volcano, and every-time it erupts, it gets bigger, until eventually it breaks the ocaen surface 4) This forms a string of Volcanic islands, known as an island arc. E.g. Ryuku Islands, Japan |
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Describe what is happening at a transform plate boundary and give an example. |
Neither Land is being made or destroyed, two plates are moving past each other. Huge Pressure is built up from the friction and when it is released, a violent earthquake occurs, but there are NO volcanoes. E.g. San Andreas Fault, California |
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Describe what is happening at a hot spots and give an example. |
Magma from the mantle erupts through the oceanic crust, creating volcanoes in chains, because the plate moves but the hot spot stays in the same place. This can be proven by radiometrically dating volcanoes and the volcanoes furthest from the Hot Spot are the oldest Over time, these volcanoes can often form volcanic islands like Hawaii. |
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What is an earthquake, and the key features? |
A violent shaking of the Earth's crust caused by plate movement, most common around plate boundaries. FOCUS - The centre of the earthquake EPICENTRE - The place on the Earth's surface directly above the focus DEPTH - The distance between the epicentre and the focus SHOCKWAVES - The waves that are given out that cause the destruction. |
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What is the Richter Scale? |
A Scale for measuring earthquakes based on measurements of it's magnitude made by a Seismograph. This allows for direct comparison of earthquakes. It is a logarithmic scale, so each whole number is a 10x increase in power, i.e. a magnitude 6 earthquake is 10x as powerful as a magnitude 5. |
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What is the Mercalli scale? |
A Scale for measuring earthquakes based on observations of the effects on people, buildings and the landscape. However, it isn't great because earthquakes in deserts would have no effect, and different people have different observations of what 'strong' is. |
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What are the factors in calculating an earthquake hazard? |
1) Power of the earthquake - More powerful earthquakes cause more damage 2) Geology - Solid rocks absorb more shockwaves, causing less damage. Weak or unsolidated rocks can liquify, destroying foundations, known as LIQUEFACTION. 3) Depth of the quake - Deeper quakes do less damage 4) Population density - If a quake hits a more densely populated area, it will cause more damage 5) Wealth of the country - Richer countries can stockpile more resources for earthquake emergencies so are less impacting, AND they can build better earthquake buildings to limit the damage |
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How can you earthquake proof a building? |
1) Reinforced lattice framework in bedrock gives strong foundations. 2) Rubber shock-absorbers between foundations and the building absorbs the shocks 3) 'Birdcage' steel frame gives the building strength and allows it to flex in a quake 4) Rolling weights on the roof to counteract shockwaves 5) Automatic shutters to prevent smashed glass falling 6) Reinforced lift shafts on the outside of the building for ease of rescue 7) Open areas to evacuate to 8) Identification number on the roof of the building for damage assessment. 9) Panels of Marble and Glass flexibly anchored to steel superstructure to prevent from falling
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Why do people live in areas of volcanic activity? |
1) Environmental - Tourist destination + Jobs that come with 2) Social - Many cannot afford to move - Some worship spirits in volcanoes - Don't wish to move from family - Many Volcanoes lay dormant for years, not worth it 3) Economic - Cheap geothermal energy (Iceland) - Very Fertile land - Lots of minerals common in volcanic areas - MONEY OUTWEIGHS THE RISK
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Why do people live in areas of Earthquake activity? |
1) Environmental - Often very beautiful - Malibu - People feel safer with earthquake proof buildings 2) Social Reasons - Chance of affected is seen as very low - There are emergency plans in place 3) Economic Reasons - Some Earthquakes are tourist destinations, providing jobs - Iceland/Turkey - Often in good mining zones - fatalities are outweighed by the money |
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How can you predict Volcanic Eruptions? |
1) Measure gas emissions - like sulfur dioxide, one of the major volcanic gasses. An increase can indicate an eruption 2) Measure the shape of the volcano with GPS as rising magma can cause it to change shape. Tilt meters can also be used 3) Measure for mini earthquakes as the magma moving can cause the ground to shake |
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How can you predict an earthquake? |
1) Preshocks, measured on a seismograph 2) Animal activity can change when an earthquake is coming, supposedly because of the low frequency noises 3) Tiltmeters measure the slope of the ground, which can change pre-earthquake 4) Changes in water levels depending on if the rocks are compressed or torn apart |
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What are the issues with predicting and preventing Earthquakes and Volcanic Eruptions? |
Neither prediction is accurate yet, and there might be lots of warning signs or none at all, for months or only hours beforehand Neither Volcanic activity or Earthquakes can be stopped, so it is just damage limitation. |
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How can you limit the damage done in a volcanic eruption or an earthquake? |
1) EDUCATION Teach people to know what to do in the event of a hazard, especially in schools. In America, FEMA gives advice on how to prepare, have an emergency kit etc 2) BUILDING DESIGN See the other question 3) DEFENCES (for lava flow) - Detonate explosives to disrupt lava flow - Construct concrete walls to deflect lava flows from important land - Spray large amount of water to cool it down, stop it and it acts as a natural dam |
