Anna Geography restless earth

Flashcards by anna.janeblue, updated more than 1 year ago
Created by anna.janeblue about 6 years ago


Geography GCSE Edexcel B

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Question Answer
What are the differences between oceanic and continental crust? Oceanic crust is made from basalt, it is more dense, fine grained and no crystals are formed in lava flows and sheets Continental crust is made from granite, it is less dense and large crystals are formed by slow cooling magma
Explain what causes/the process of convection currents Radioactive decay in the Earths core generates energy Heated material becomes less dense and rises Material cools as it reaches the surface, becomes more dense and sinks Causes tectonic plates to move
Destructive plate boundary oceanic crust and continental crust collides, more dense oceanic crust subducts, deep sea trenches, volcanoes, pressure+friction=earthquake E.g Nazca and S.A plate
Constructive plate boundary Oceanic crust Rising convection currents in mantle causes plates to spread apart Magma rises between two plates Formation of new oceanic crust No earthquakes E.G mid Atlantic ridge
Conservative plate boundary Two continental plates Push past pressure+friction= Earthquake No plate created or destroyed No volcanoes E.G. San Andreas Fault
Collision plate boundary Two continental plates Compress,fold mountains Buckling No subduction No volcanoes pressure+friction= volcano E.G. African and Eurasian=Alps
Define Focus Place in crust where pressure is released
Define epicentre Area of land directly above the focus
Define seismic wave Energy released from the focus (strongest at epicentre)
5 Key features of an earthquake Caused by movement of tectonic plates Occur along plate boundary Plates do not move smoothly, pressure builds up and sudden movement Most severe damage on epicentre Pressure released from focus
How do you measure the power of an earthquake? Seismometre
How do you measure the magnitude of an earthquake? Ritcher Scale (1-10)
Name of the graph you plot the information from a seismometre onto seismograph
Why are earthquakes hard to predict? Unknown when pressure will be released and the magnitude of it No way to measure the tectonic plate movement
Primary effects of an earthquake Roads crack Walls collapse Landslides
Secondary effects of an earthquake Fires Lack of food/water disease breaks out
what causes aftershocks and what effect do they have? Rocks settle in new position Injure/Kill people Destroy buildings weakened by earthquake
What is a tsunami? Series of waves produced by an earthquake
What can be done to improve buildings Cross bracing Shock absorbers Steel frame Double glazed windows Shear walls Knee braces Deep foundations
What can be done in preparation for an earthquake? Transport route Build buildings safely, follow rules Evacuation route Monitor region
Define a)short term relief b)long term planning a) help provided to prevent death because of water, food or shelter shortage b) plans beyond immediate cost
What is the immediate response to an earthquake? Evacuation Shelter Medical help Look for survivors Food and Water Sewage, toilets, contaminated water
Define capacity Ability to recover from a natural disaster
Define preperation Ready to respond well to a natural disaster
Define mitigation Reduce effect or vulnerability to a natural disaster
Describe an Ash cone Wide crater Concave sides Cone formed of ash and cinders E.G. Monte nuova italy
Describe lava domes and spines Convex sides Cone made of lava layers which harden quickly E.G. Puy de dome France
Describe calderas Wide crater After big eruption magma chamber nearly em[ties so cone collapses inwards
Describe a shield volcano Gently sloping sides Formed of basaltic lava which flows a long way before solidifying Fluid lava No steep gradient
Describe a composite volcano Andesitic lava which is very explosive and has a high gas content Layers of ash and lave= viscous Destructive plate boundary E.G. Pinatubo Philappenes
What are the a) positives b) negatives to living in a volcanic area? a)small population, more resources, geothermal energy, rich fertile soil, tourism, ideal for farming b)dangerous, loss of life, money, homes, crops, live stock, livelihood, Acidic water and rain, lahars, destruction of buildings,
How can you predict a volcanic eruption? measure earth tremors (seismometre) Tiltmetres or lasers to show swelling Chemical sensors measure for an increase in sulfur dioxide
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