St Ivo School Geography Department - GCSE REVISION
Define the following key terms...
2. Focus 3. Magnitude Yr 11 - Tectonics
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1. Epicentre
1. Epicentre - this is the point on the surface directly above the focus of an earthquake - the most damage often occur here 2. Focus - this is the point underground where the earthquake starts - it is here where the greatest release of energy occurs 3. Magnitude - the strength of an earthquake, reflecting the amount of energy released. www.geobytesgcse.wordpress.com
Ocean-Continental Plate Boundary
St Ivo School Geography Department - GCSE REVISION
What type of boundary is shown in the diagram below? - Describe what happens here.
Yr 11 - Tectonics
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an oceanic and continental plate move towards each other due to convection currents denser oceanic crust is subducted forming a deep sea trench heat from the mantle & friction between the plates causes the oceanic plate to be destroyed as the plate melts, magma forms and due to the pressure and the heat is forced to rise to the surface magma erupts at the surface as lava, forming a volcano fold mountains (e.g. Andes) are created due to the impact of www.geobytesgcse.wordpress.com collision (earthquakes may occur)
St Ivo School Geography Department - GCSE REVISION
1. An oceanic-oceanic convergent boundary 2. A continental-continental boundary 3. A divergent plate boundary 3. A conservative plate boundary Yr 11 - Tectonics
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Give a named example of:
1. Oceanic-Oceanic (Convergence) - Philippine Plate moving west & subducting under the Eurasian plate (forms the Ryuku Islands - nr Japan) 2. Continental-Continental (Convergence) Indian Plate converging with the Eurasian plate - forms the Himalayas 3. Divergent Boundary - North American Plate moving away from the Eurasian Plate (forms Mid-Atlantic Ridge) 4. Conservative Boundary - North American and Pacific Plate move past each other at the San Andreas Fault (California) www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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Give three differences between oceanic and continental crust.
Oceanic crust is 5-10km thick (Continental 25-100km)
Oceanic crust is denser than continental crust
Oceanic crust is constantly renewed and destroyed (continental is permanent and cannot be destroyed.
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St Ivo School Geography Department - GCSE REVISION
Name the features at A, B, C and D
A - Subduction Zone B - Oceanic Trench
Yr 11 - Tectonics
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C - Island Arc D - Volcano www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
Points should include: Both earthquakes & volcanoes occur in long narrow bands - often following the edge of continents (e.g. W Coast of S America) Largest band of volcanoes are found along the Pacific Ring of Fire (around the Pacific Ocean) Earthquakes and Volcanoes are also found together in bands in the middle of Oceans (e.g. Mid-Atlantic Ridge) NOT all follow the same pattern - some volcanoes are found in isolated clusters - e.g. Hawaiian Islands - middle of Pacific Plate)
Yr 11 - Tectonics
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Describe the global distribution of earthquakes and volcanoes.
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St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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What is meant by a convection current and how does it result in plate movement?
Convection currents are movements of hot molten rock. Magma is heated lower in the mantle and rises As it spreads out under the crust it carries plates with it As two currents diverge - plates move away from each other As the magma cools it sinks down to be reheated Where two currents converge, two plate move towards each other www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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At which plate boundary will oceanic trenches, volcanoes and fold mountains be found?
Oceanic-continental convergence boundary (destructive boundary) - i.e. where subduction of oceanic crust creates oceanic trench, and forms volcanoes and the collision between the plates creates fold mountains. www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
Describe the formation of fold mountains.
Yr 11 - Tectonics
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Fold mountains may from at either continental-continental convergent plate boundaries or oceanic-continental convergent boundaries. At these boundaries as the two plates meet, the force of the collision causes folding and faulting to occur This results in uplift of rock and sediment squeezed during the collision The result is fold mountains such as the Himalayas www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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What is meant by a hot spot?
A hotspot is a plume of hot molten material rising from the mantle. This magma is lighter than the surroundings and rises - erupting at the surface where the crust is thin, creating a volcano (and eventually a volcanic island) They are fixed within the mantle & as the crust moves over the top - a chain of volcanic islands is left behind (e.g. Hawaii)
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St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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Explain the processes at a divergent plate boundary
- two plates move away from each other due to convection currents - as the plate move apart, pressure causes the crustal rocks to fracture and a gap and ridge (mid-oceanic ridge) form - magma rises to fill the gap, volcanoes form and new crust is created - as magma builds up, volcanic islands form above the surface of the ocean (e.g. Surtsey, Iceland) - Often have earthquakes associated with these boundaries. www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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What factors can affect the amount of damage caused by an earthquake?
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1. Mercalli scale measure damage caused by an earthquake whereas the Richter scale measures
Give four differences between the Mercalli scale and the Richter Scale.
Yr 11 - Tectonics
1. Time of day 2. Magnitude of Earthquake 3. LIC / HIC 4. Level of preparedness 5. Rural or Urban area 6. Distance from epicentre
the magnitude 2. Mercalli scale measurements are based on observations of damage to buildings whereas the Richter scale is based on scientific measurements from a seismometer 3. Mercalli scale is subjective - the Richter scale is quantitative 4. The Mercalli scale is not useful in uninhabited areas (few visible effects). Richter scale can be used to measure earthquake vibrations anywhere (if seismometer in place). www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
Each level on the scale represents a 10x increase in energy from the previous one.
Yr 11 - Tectonics
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The Richter Scale is a logarithmic scale. What does this mean?
St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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Using specific examples describe four reasons for people continuing to live in areas of volcanic activity.
Therefore an earthquake measuring 6 on the Richter scale is 10x stronger than one measuring 5 and 100x stronger than one measuring 4. www.geobytesgcse.wordpress.com
1. Tourism - volcanic areas such as Iceland and New Zealand are popular tourist attractions - with many attractions - e.g. Blue Lagoon - Iceland. Provides jobs and important income - therefore many work in tourism industry in these areas. 2. Poverty - lots of people, particularly in LICs cannot afford to move 3. Geothermal Energy - in Iceland 28% of electricity comes from geothermal sources - an valuable and cheap source of energy 4. Fertile soils - provide excellent opportunity for growing crops - both for subsistence farming - e.g. rice farming - Mount Pinatubo and commercial farming - e.g. Olives and grapes (Mount Etna) could also include... precious minerals available; low perceived risk; people's beliefs (Merapi - Indonesia) www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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State 6 reasons why people continue to live in volcanic areas.
St Ivo School Geography Department - GCSE REVISION
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Using examples, describe four reasons why people continue to live in earthquake prone zones.
Yr 11 - Tectonics
1. Precious Minerals 2. Fertile Soils 3. Perceived Risk seen as worth it 4. Poverty 5. Geothermal Energy 6. Tourism also beliefs (e.g. Merapi - believed to be sacred)
1. Technology - increased confidence due to earthquake proof buildings and disaster management plans in place 2. Lack of choice - many have no choice but to - either because of poverty or the fact that most of their country is tectonically active (e.g. Japan) 3. Many e/q prone areas are also popular tourist areas therefore people prepared to take the risk because of jobs 4. Some having never experienced a quake in their lifetime think www.geobytesgcse.wordpress.com the changes of them being affected are low.
St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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Outline the economic reasons for people continuing to live in areas prone to volcanic activity.
Tourism - volcanic areas popular with tourists - e.g. Iceland with attractions like Blue Lagoon, Strokkur Geysir - provides 5000 jobs and accounts for 5% of Iceland's earnings. Mount St Helens - has become national monument - popular tourist area (and souvenirs sold) Fertile soils - provide rich opportunities for growing crops to be sold (e.g. Mount Etna, Sicily - grapes, olives & citrus fruits grown on slopes). Precious minerals like gold, diamonds and sulphur found in these areas Important source of cheap geothermal energy - Iceland 28% of electricity from geothermal sources. www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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Why have improvements in technology led to people continuing to remain in earthquake areas in HICs?
People now feel safer living in earthquake zones. In many earthquake prone areas in HICs new technologies used to earthquake proof buildings - e.g. reinforced foundations / counterweights such as those in Japan and California (e.g. Transamerica building - San Francisco) - also advanced rescue equipment and detailed disaster plans in place. www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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For a named case study, describe the causes of a major earthquake.
Haiti - located on the boundary between the Caribbean and North American plate - on a transform / conservative plate boundary Both plates moving at about 20mm a year - Caribbean plate moving East and North American plate moving west Movement between plates not smooth - friction occurs and strike slip motion 12th Jan 2010 - release of pressure resulted in major earthquake www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
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Yr 11 - Tectonics
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Including specific facts and figures give five effects of the Haiti quake on the environment.
St Ivo School Geography Department - GCSE REVISION
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Including specific facts and figures give five effects of the Haiti quake on people.
Yr 11 - Tectonics
Building waste major problem - 50% of buildings in Port-au-Prince and nearby towns collapsed - including 500 schools, and buildings such as Presidents Palace and Port-au-Prince cathedral problem of massive quantities of rubble to dispose of landslides and floods now more likely due to slopes destabilised by quake sewage disposal problems caused pollution fears for fragile ecosystems such as forests and coral reefs trash filled beaches and polluted waterways - swarms of dead fish
220,000 people died and 1.5 million made homeless many left traumatised children orphaned, lost or given away in the chaos (some taken out of country illegally for adoption) 500 schools destroyed - massive impact on education 1 in 5 jobs lost City leaders / politicians killed (inc. Archbishop of Port-au-Prince) Riots and looting / civil unrest - as relief workers held up by 49 hours many died of broken limbs (severe lack of doctors)
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St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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Why were the effects of the earthquake in Haiti so bad?
Haiti - poorest country in the Western World (3 million live in slum conditions in Port-au-Prince - slum buildings collapsed easily in quake Haiti had already suffered severe damage from storms in 2009 (already vulnerable) Poor infrastructure - rescue attempts made difficult Main roads out of capital still blocked 10 days after quake Poor quality buildings - collapsed easily Many hospitals destroyed in the quake Haiti airport - only one runway - control tower damaged in quake - 48 hour hold up of relief workers and supplies www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
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St Ivo School Geography Department - GCSE REVISION
Is it possible to predict volcanoes? Give 4 warning signs that a volcanic eruption may be imminent.
Yr 11 - Tectonics
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Can be difficult to pinpoint exactly when an eruption will occur, but it is possible to monitor for increased activity and threat of eruption which can enable successful evacuation and the saving of lives (e.g. Popocatepetl, Mexico - 2000 - successfully evacuated)
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Yr 11 - Tectonics
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Identify two short term and two long term effects of an earthquake.
Short Term Effects: - injuries - riots and chaos Long Term Effects: - Cost of repairs to infrastructure - emergency accommodation for those who have lost homes - impact on economy - spread of disease
- Increase in earthquake activity (indicating rising magma) - Increase in Sulphur dioxide (released as magma rises) - Bulging of volcano / change of shape - as magma builds up - Increase in ground temperatures (as magma rises)
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St Ivo School Geography Department - GCSE REVISION
Examples Include:
Yr 11 - Tectonics
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Describe and explain four techniques for monitoring volcanoes.
St Ivo School Geography Department - GCSE REVISION
Can be difficult to manage volcanic hazards mainly involves management of lava flows:
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Describe efforts made to reduce the impacts of volcanic eruptions on people.
Yr 11 - Tectonics
Tiltmeters / GPS technology - on side of volcanoes to detect change in shape which may indicate magma rise (e.g. Mount St Helens 1980) Gas Sampling - monitor levels of Sulphur dioxide which increase with volcanic activity Geothermal Monitoring - satellites used to detect changes in heat levels associated with magma rising. Seisometers - used to monitor earthquakes (often precede eruptions - resulting from rising magma fracturing rock).www.geobytesgcse.wordpress.com
- explosives to divert lava flow from villages (e.g. Mt Etna - 1996) - spraying large volumes of water on lava flow (cool and solidify advancing lava flows - successful in Heimaey (Iceland) - 1973 to save port from lava flow - earth walls / concrete barriers to deflect lava flows (e.g. Mauna Loa - Hawaii - used to protect observatory) - digging ditches to divert lava flow pathway (e.g. Mt Etna '91-93) www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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Is it possible to predict earthquakes?
St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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Possible techniques include: Strange animal behaviour - often noted before earthquakes (e.g. 2008 China earthquake - plague of migrating frogs noted shortly before quake) Seismometers - continuing monitoring of ground movements - small foreshocks sometimes precede major quakes Seismicity patterns - look for patterns in occurrence of past earthquake and likelihood of another Measuring electrical discharge (evidence of rise before earthquakes)
St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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Could include: Earthquake proof building design (computer controlled counterweights on roof; rubber shock absorbers between foundations and building, automatic shut off switches for electricity and gas etc.) Emergency Drills - e.g. 1st Sept (Japan) - held annually to prepare people for what to do in event of an earthquake Education - ensuring people know how to prepare (e.g. emergency survival kit including torch, food, water etc.) and how to react. Well trained emergency services (with appropriate equipment) Planning restrictions (types of land, height etc.) www.geobytesgcse.wordpress.com
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Describe three ways in which the impacts of earthquakes can be minimised.
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Describe two techniques which have been used to try and predict earthquakes.
No - very difficult to predict as don't occur at single visible location and can occur without warning. Can also occur at small, often unknown faults. Whilst seismic monitoring is undertaken, best early warning systems in places such as Japan - only provide a few seconds between when an earthquake starts and being felt in an area.
St Ivo School Geography Department - GCSE REVISION
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Yr 11 - Tectonics
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Describe examples of what can be done to help limit the damage caused by earthquakes to buildings.
Foundations sunk deep into bedrock (avoid clay therefore reduce risk of liquefaction) Rubber Shock-absorbers between foundations / building to absorb energy waves computer controlled counter-weights on roof (reduce movement) automatic shut off switches for electricity and gas interlocking steel frames (sway during earth movements) EXAMPLES - Transamerica Building (San Francisco) - triangular building - wide stable base and steel frame.
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St Ivo School Geography Department - GCSE REVISION
How can educating people help to save lives in a natural disaster such as an earthquake?
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Yr 11 - Tectonics
increase awareness of what to do in the event of an earthquake (e.g. through Disaster drill days) helping to save lives educate people about the importance of being prepared - e.g. survival kit - can help save lives in event of quake - e.g. food/water if trapped for several days and basic first aid supplies www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
(i) earthquake (ii) pyroclastic flow (iii) subduction zone Yr 11 - Tectonics
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Define the following key terms:
Earthquake - a sudden and often violent shaking of the earth's crust due to the release of energy in the form of seismic waves Pyroclastic Flow - a high velocity avalanche of hot gas, ash and volcanic rocks (up to 150km/hr) Subduction Zone - the place where one tectonic plate sinks below another. www.geobytesgcse.wordpress.com
Define the following key terms: (i) Lahar (ii) Magma (iii) Lava Yr 11 - Tectonics
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St Ivo School Geography Department - GCSE REVISION
Lahar - a volcanic mudflow - created by the combination of ash and water Magma - molten rock under the surface of the earth Lava - molten rock on the surface of the earth
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Define the following key terms: (i) Convection Current (ii) Volcano (iii) Crust Yr 11 - Tectonics
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St Ivo School Geography Department - GCSE REVISION
Convection current - a circulatory movement of hot molten rock in the mantle (caused by heating from the core) which results in the movement of crustal plates. Volcano - an opening in the earth's crust through which lava, gas and ash erupts Crust - the outer layer of the earth. www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
1. Oceanic Trench Name the features found at an oceanic-oceanic convergence zone.
2. Subduction Zone
Yr 11 - Tectonics
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3. Volcanic Islands 4. Island arc www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
1. Oceanic Trench Name the features found at an oceanic-continental convergence boundary.
2. Subduction Zone
Yr 11 - Tectonics
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3. Fold Mountains 4. Volcanoes www.geobytesgcse.wordpress.com
St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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Describe an oceanic trench.
Long, deep and narrow features - form the deepest part of an ocean floor, marking the point where one plate is being subducted under another.
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St Ivo School Geography Department - GCSE REVISION
Yr 11 - Tectonics
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1. Date - Tuesday January 12th 2010 - 4.53pm 2. Magnitude - 7 on the Richter Scale 3. Focus - shallow (only 13km down) 4. Lasted 35-60 seconds 5. Epicentre - at Leogane (25km SW of Port-au-Prince)
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1.What was the date of the Haiti earthquake? 2.What was the magnitude of the Haiti earthquake? 3.How deep was the focus of the Haiti earthquake? 4.How long did the Haiti earthquake last? 5.Where was the epicentre of the Haiti quake?
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Name an example of: - Fold Mountains - Oceanic Ridge - Islands created by a hotspot - Convergent Boundary - Transform Fault Yr 11 - Tectonics
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St Ivo School Geography Department - GCSE REVISION
Fold Mountains - Himalayas or Andes Oceanic Ridge - Mid-Atlantic Ridge Islands created by a hotspot - Hawaiian Islands Convergent Boundary - Nazca and South American Plates meeting Transform Fault - San Andreas Fault (California) also known as a conservative boundary www.geobytesgcse.wordpress.com
