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92 Cards in this Set
- Front
- Back
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Describe the Lower Mantle: |
- situated between the upper mantle and the outer core - solid - made up of perdotite - 1600 - 4000 degrees - 4.4 - 5.6 g/cm cubed - denser than the asthenosphere |
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Describe the Asthenosphere: |
- just below the lithosphere - upper part of mantle and crust - 900 - 1600 degrees - liquid - partly molten and solid rock - lubricating layer made of peridotite - consistency of porridge - density between 3.4 and 4.4 g/cm cubed - helps the plates move |
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Describe the Inner Core: |
- 5000 - 6000 degrees - 5100km from Earth's surface - solid - made from nickel and iron - 15g/cm cubed |
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Describe the Outer Core: |
- made up of nickel and ron - 2900km from Earth's surface - liquid - allows convection currents to take place - 4000 to 5000 degrees - 9.9 to 12.2 g/cm cubed |
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Describe the Lithosphere: |
- oceanic and continental crusts - both are between air temps and 900 degrees - OC - 3.3g/cm cubed and CC - 2.7g/cm cubed - oceanic crust is denser - OC - basaltic and CC - granite - solid so can stand on it |
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Describe the 3 main differences between Oceanic and Continental Crust: |
- the OC is 7km thick whereas the CC is 100km thick - the OC is a lot younger being only around 180 million years old whereas the CC is a lot older being between 3 to 4 billion years old - there is new OC created daily and older crust is subducted and destroyed whereas the CC does not subduct or get destroyed as it has a lower density |
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Describe how Tectonic Plates are moved: |
- The radioactive decay of uranium in the inner core releases lots of heat energy - This heats the magma, which is less dense, so it rises. - As it rises, it cools, becoming more dense and sinking to the bottom again. - This creates a convection current which moves the tectonic plates. - This happens in the mantle. |
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What is the Earth surrounded by? |
a huge invisible magnetic field called the magnetosphere |
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What is the magnetosphere? |
a force field which protects the Earth from harmful radiation from space and the sun |
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What is the magnetosphere made by and how does it do this? |
the outer core - as liquid iron in the outer core flows, it works like an electrical dynamo - this produces the magnetic field |
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Describe a diagram of the magnetosphere: |
- there is radiation from space - it is deflected around earth by the magnetosphere - the earth's outer core creates the magnetic field like a huge bar magnet |
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Describe a diagram of a Destructive plate boundary and a case study of where these can be found: |
Japan and the west coast of South America |
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Describe what happens at a destructive plate boundary: |
- the OC is denser (heavier) than the CC so the CC forces the OC underneath. - this is called subduction - at the subduction zone a deep sea/ocean trench is formed where the OC is forced down - when the OC melts as it goes down into the mantle it floats back up because it's lighter than the mantle - the magma can then erupt to create volcanoes |
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How can destructive plate boundaries cause tectonic hazards? |
- creates earthquakes when subducting and volcanoes from magma floating up |
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Describe a diagram of a Conservative plate margin and a case study: |
- case study - California, USA (but also canada and mexico on the same fault line
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Describe what happens at a Conservative plate margin: |
- plates move alongside each other in opposite directions and same speeds or different speeds and the same direction - the plate margins are made of jagged, brittle rock so can't slide past each other - the pressure builds and they jerk forwards - this sudden movement and release of pressure causes earthquakes |
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Describe a diagram of a Collision plate margin and the case study: |
- layers - cont. crust, lithosphere, atmosphere and ancient OC crust at the bottom - Himalayas |
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Describe what happens at a collision plate margin: |
- when the CC meets CC neither can subduct the other so they are forced together at a high pressure - the rocks crumble and form huge mountain chains like the Himalayas - the Himalayas are still growing as the plates continue to be pushed at 1cm or 2cm a year |
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Describe what collision plate margins form: |
- form mountains and mountain ranges - fold mountains when rocks collide together and fold together - the earth's crust is the thickest at this point |
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Describe a diagram of a constructive plate margin and a case study: |
- Iceland, mid-atlantic ridge between the UK and the USA - creates small chains of islands |
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Describe what happens at a constructive plate margin: |
- if the OC pulls away from other OC new crust is made and the sea floor grows - the sea floor is spreading - it is impossible for there to be gaps on Earth as the mantle rises and solidifies to fill the space - small chains of islands are created as new crust is created and builds a small volcano that sometimes breaks the surface of the water |
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Describe which plates are involved in destructive plate margins in the world: |
- Japan - Eurasian plate pushing against Pacific plate - South America - Nazca plate pushing against the South American plate |
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Describe which plates are involved in conservative plate margins in the world: |
- California, Canada and Mexico - Pacific plate moving alongside the North American plate |
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Describe which plates are involved in collision plate margins in the world: |
- Himalayas - African plate and Indo-Australian plate moving against the Eurasian plate |
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Describe which plates are involved in constructive plate margins in the world: |
- Iceland - North American plate moving away from the Eurasian plate in the Atlantic ocean - Mid-Atlantic ridge - North American plate moving away from the Eurasian and African plates |
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What are the 4 types of plate margins but which are the 3 most common? |
- destructive, conservative, collision and constructive - destructive, constructive and conservative |
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Where do earthquakes and volcanoes normally, BUT NOT ALWAYS, occur? |
along plate boundaries, as most occur here but some are on land or in the sea |
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Describe the different depths of earthquakes and their names: |
- 0-70kms - shallow - 70-300kms - intermediate - 300-700kms - deep |
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Which types of earthquake are generally more harmful? |
shallow as there is less distance for the energy of the waves to travel before it hits earth and destroys everything |
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What is the focus and what is the epicentre? |
- the focus is the point within the earth where the earthquake rupture starts - the epicentre is the point directly above the focus at the surface of the earth |
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Where are earthquakes measured from? |
distance from earthquakes and earthquake locations are measured from the epicentre |
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What are the 3 main causes of tsunamis? |
- ocean floor earthquakes - underwater volcanic eruptions - underwater landslides |
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Describe how a tsunami is grows: |
- as it approaches land the water gets shallower so the wave is compressed which means it gets higher and faster - the wave height can be 25m or higher - the wave can be extremely long - in open water between 100-1000km - they travel at speeds of 640-960km/h - it is usually a series of waves - more than one - the time between each wave can be between 10 and 60 minutes - it piles up as a massive wall of water as it approaches the coast |
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Describe how a tsunami is formed: |
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How was the boxing day tsunami formed? |
- result of the Indio-Australian plate subducting below the Eurasian plate - caused by an earthquake at a destructive plate margin that measured more than magnitude 9 - the earthquake caused the seafloor to uplift, displacing the seawater above - in open ocean the tsunami measured less than 1m high - the tsunami travelled at speeds up to 800km/h - when the tsunami reached the shore the height of the wave increased to 15m in some areas |
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What were the social primary effects of the boxing day tsunami? |
- 250,000 deaths - 2 million homeles - around 32000 missing - 1000s injured - 13 countries affected |
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What were the economic and environmental primary effects of the boxing day tsunami? |
- buildings destroyed - economic and environmental as takes money to replace them and would have harmed trees etc - vegetation destroyed and animals killed |
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What were the social secondary effects of the boxing day tsunami? |
- diseases like cholera were rife due to lack of clean drinking water - lack of food, water and healthcare - communication and transport links destroyed |
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What were the social economic effects of the boxing day tsunami? |
- lack of income from tourism for the whole country as no-one was visiting or wanted to visit - had to re-build houses and transport and communication links |
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What were the environmental secondary effects of the boxing day tsunami? |
- ecosystems disturbed - species dying out etc |
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What were the immediate responses to the boxing day tsunami? |
- the USGS warned Africa, saving lives - Action Aid raised £13 million and immediately sent food aid - Action Aid also offered psychological counselling, paid for housing, paid for boats with motors for fishing communities, rebuilt schools and community centres in an attempt to rebuild areas - food and agriculture organisation of the UN trained 140 boat builders and supplied 200 boats - country governments helped rebuild whole towns including in Indonesia in Aceh province - an early warning system has now been put in place in the Indian Ocean with co-operation from many governments - the UK's disasters an emergency committee established an emergency fund almost immediately - the DEC earthquake/tsunami disaster appeal fund stood at £32 million, up £7 million in one night from the 31st of December. At one point it was receiving around £15,000 a minute in donations via phone and internet - countries sent aid teams immediately - MEDCs such as the UK sent dog teams, forensic experts and equipment to help identify bodies and clean up after the tsunami - many people have re-established buildings and businesses in the affected regions but many people permanently migrated from the area |
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Describe the radius of the tsunami and the countries affected: |
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What were the environmental primary effects of the Mount St Helens, Washington, USA volcano? |
- pyroclastic flow flattened and burnt trees over 360sqkm - 7000 animals killed in the forests - 12 million salmon in a fish farm were killed
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What were the social primary effects of the Mount St Helens, Washington, USA volcano? |
- 61 people died, mainly scientists and photographers
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What were the economic primary effects of the Mount St Helens, Washington, USA volcano? |
there were none |
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What were the environmental secondary effects of the Mount St Helens, Washington, USA volcano? |
- hot magma melted snow which created mudslides - smoke, dust and ash created a cloud - ash settled in a 15cm deep layer which ruined crops - there was an increased risk of flooding due to the new landscape |
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What were the social secondary effects of the Mount St Helens, Washington, USA volcano? |
- because of the smoke, dust and ash cloud planes had to be diverted - ash settled in a 15cm deep layer which made roads unusable, ruined crops and farm machinery (no food) |
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What were the economic secondary effects of the Mount St Helens, Washington, USA volcano? |
- ash settled in a 15cm deep layer altogether causing $175 million worth of damage - US government gave $951 million to rebuild the area and compensate - area became a tourist attraction so made the local economy wealthier |
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When did Mount St. Helen's erupt and where is it? |
18th May, 1980 Washington, USA |
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Where is Mount Nyiragongo and when did it erupt? |
Democratic Republic of Congo 17th January 2002 |
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What were the primary social effects of the Mount Nyiragongo eruption? |
- around 100 people died - 12500 homes destroyed by lava flows - 400,000 people had to be evacuated to overcrowded refugee camps - 120,000 people were made homeless |
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What were the primary economic effects of the Mount Nyiragongo eruption? |
there were none |
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What were the primary environmental effects of the Mount Nyiragongo eruption? |
there were none |
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What were the secondary social effects of the Mount Nyiragongo eruption? |
- there was disruption to the mains water supplies which caused concern for the spread of disease - poisonous gases caused acid rain which affected the farmland and cattle (no food) - due to poverty, most could not afford to rebuild homes - there was little clean water, food or shelter so diseases like cholera were at risk of spreading |
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What were the secondary economic effects of the Mount Nyiragongo eruption? |
- poisonous gases caused acid rain which affected farmland and cattle so many farmers lost income - due to poverty no-one could afford to rebuild their home |
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What were the secondary environmental effects of the Mount Nyiragongo eruption? |
there were none |
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Describe what a composite volcano looks like and a case study: |
- Mount Pinatubo, Phillipines, Mount St, Helen's and Mount Nyiragongo |
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How are composite volcanoes formed? |
- formed when acidic lava (felsic) is sticky and makes steep sided mountains along destructive plate margins |
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What are composite volcano eruptions like? |
- extremely violent as it was originally OC so the magma contains a lot of water which as steam increases the pressure in the lava tube |
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What are composite volcano's magma like and what are the hazards? |
- the magma is viscous and sticky and traps hot gases within it, releasing them suddenly in an eruption - hazards include ash and rock as rock plugs are left over from previous eruptions and then blown off in future eruptions |
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Describe what a shield volcano looks like and a case study: |
- Mauna Loa, Hawaii |
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Describe how a shield volcano is formed: |
- formed when the lava is basic (opposite to acidic) - found along constructive plate margins, like Iceland, and near hot spots, like Mauna Loa in Hawaiian islands |
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What are the magma and eruptions like in shield volcanoes? |
- magma is not viscous so releases gases preventing a build-up of pressure - eruptions therefore tend not to be explosive |
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What are the hazards of a shield volcano? |
- most common are lava flows, but others such as airborne ash particles, volcanic gases and ground cracks can be experienced |
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Where is Mauna Loa, what type of volcano is it and when did it last erupt? |
Hawaii, shield, 24th March-15th April, 1984 |
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Describe the cause of Mauna Loa's eruption: |
it is located on a hot spot |
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Describe the social, economic and environmental effects of Mauna Loa's eruption: |
S: a huge pyroclastic flow thundered down at the end of 1983/beginning of 1984, reaching towns in as little as 7 hours and destroying 16 houses S :it also destroyed coastal highways and beaches Ec: lava flow destroyed 100s of visitor centres Ec: tourism was pretty low for the next 10 years due to the eruption Env: lava destroyed the view as it destroyed hills and beaches |
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What are the 4 main ways to monitor volcanoes? |
- ground deformation, seismicity, hydrology and gas output |
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Describe how volcanoes are monitored: |
- aircraft are used to measure the amount of gas the volcano gives off - tilitmeters detect when the volcano swells up as it fills with magma - hot springs are monitored - concrete shelters protect against volcanic bombs and ash - evacuation routes are clearly sign posted and there are regular evacuation drills - concrete lahar channels divert dangerous mudflows - tunnels in the volcano have seismometers which monitor earthquakes that increase as magma rises so scientists can predict the eruption - boreholes measure water temperature as magma heats it up |
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What makes a place vulnerable to tectonic hazards? |
- being located on a plate boundary - having little technology to predict them - having unstable buildings with weak foundations |
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What are the 2 ways in which tectonic hazards can be managed? |
Preparation and Mitigation (reducing the impact) |
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What is preparation (when managing tectonic hazards)? |
- governments, communities and individuals would be ready to respond rapidly when disaster strikes and cope with the situation effectively - these measures include the formation of emergency plans, the development of warning systems and the training of personnel - the measures may include evacuation plans for areas that may be at risk from a disaster and training for search and rescue teams - preparation minimises loss of life, disruption of critical services and damage` |
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What is mitigation (when managing tectonic hazards)? |
- reduces the effect of the hazard and the vulnerability of it in order to reduce the scale ofr the disaster - they can be focused on the hazard itself or on the elements exposed to the threat - hazard-specific measures may include relocating people away from the hazard-prone areas and strengthening structures and using hazard-resistant design to reduce damage when a hazard occurs |
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With Monserrat in mind, what are the advantages and disadvantages of evacuating large areas? |
+ saves lives - reduces population - burdens immigrants on other countries |
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What are 3 ways in which to make buildings hazard resistant? |
- reinforced buildings - strong foundations - flood walls |
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How are tall steel buildings in MEDCs (such as Japan) built to be hazard resistant? |
- a damper in the roof acts like a pendulum, reducing the building's sway - cross bricking stops floors collapsing - shock absorbers built into cross braces - a strong steel frame which is also flexible, stops cracking - strong double glazed windows stop broken glass showering down - very deep foundations to prevent collapse |
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How are wooden mud huts on sticks in LEDCs (China) built to be hazard resistant? |
- lightweight thatch roof - walls made of mud and straw packed between wooden slats - simple steel rod foundations - concrete rings tie the walls to the foundations
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What hazards are caused by destructive plate boundaries?
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- earthquakes are very destructive, up to magnitude 9
- tsunamis can form - volcanoes are very explosive and destructive - volcanoes are steep sided and cone shaped - they erupt endesite lava at 900-1000 degrees Celsius |
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What are the hazards caused by the conservative plate margins?
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- creates destructive earthquakes up to magnitude 8.5
- small earth tremors almost daily - no volcanoes |
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What hazards are caused by collision plate margins?
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- destructive earthquakes, up to magnitude 9
- landslides are triggered - volcanoes are very rare |
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What hazards are caused by constructive plate margins?
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- creates small earthquakes up to 5.0-6.0 on the Richter scale |
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What is the power of an earthquake also known as? |
- how much the ground shakes - its magnitude |
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What does a seismometer measure and how? |
measures magnitude using the Richter scale or the Moment magnitude scale |
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What is the Richter scale? |
- it is a logarithmic scale - a magnitude 6.0 earthquake is 10 times more powerful than a magnitude 5.0 |
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Describe the richter scale and what impact certain magnitudes can have: |
- major earthquakes cause huge devastation - strong earthquakes cause lots of devastation and deaths - small is where damage begins, but deaths are rare |
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Describe how earthquakes waves travel and how earthquakes tend to be worse: |
- earthquake waves travel out in all directions - the arrows represent plate movement - the shallower the focus, the more destructive the earthquakes tends to be - the epicentre experiences the most shaking |
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Where is Kobe, when did it happen and what were the causes? |
- Japan, 1995 - magnitude - 7.2 (soft ground also made shaking worse) - focus - 16km deep on a fault - epicentre - 20km from Kobe population 1.5 million) |
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What were Kobe's primary effects? |
- 5000 people died - 25,000 injured - population density was very high and people were still in bed when it struck at 5:46am - bridges and roads collapsed, train lines were damaged - disrupting transport and communication links - £100 billion of damage was caused to roads, houses, factories and infrastructure (gas, electric, water and sewage pipes) |
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What were Kobe's secondary effects? |
- many fires broke out throughout the city, triggered by broken gas pipes, resulting in further deaths - businesses were affected for many weeks due to disruption caused by rebuilding - homelessness, disrupted schooling, unemployment and increased stress problems lasted for many months as the authorities struggled to cope with the scale of the damage caused |
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Where is Port-au-Prince, when did it happen and what were the causes? |
- Haiti, 2010 - magnitude - 7.0 - focus - 13km deep on a conservative plate boundary - epicentre - 25km from Port-au-Prince (population 2.5 million) |
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What were Haiti's primary effects? |
- 316,000 people died and a further 300,000 were injured - many houses were poorly built and collapsed instantly - 1 million people were made homeless - the port, communication links and major roads were damaged beyond repair - rubble from collapsed buildings blocked road and rail links |
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What were Haiti's secondary effects? |
- the water supply system was destroyed - a cholera disease outbreak killed over 8000 people - the port was destroyed - making it hard to get aid to the area - Haiti's important clothing factories were damaged. These provided over 60% of Haiti's exports. I in 5 jobs were lost - 1 year after the earthquake, 1 million people remained displaced - many still living in refugee camps |
