Key term
WJEC A-Level Geography 601-8455-3
Coastal Landscapes
Topic overviewThe coast as an open systemSediment sources and sediment cellsTides and coastal currentsConstructive and destructive wavesHigh energy coasts and erosional landscape systemsLow energy coasts and depositional landscape systemsFetch, wave refraction and wave energyLithology and structural geology at the coastSub-aerial weathering and mass movementMarine processes of erosionErosional landforms of rocky coastsCoastal transport and longshore driftDeposition, flocculation and sediment sortingDepositional landforms of sandy coastsSand dunes and aeolian processesEstuaries, tidal flats and salt marshesCoral reefs and mangrove coastlinesCoastal change over different timescalesCoastal processes and human activityHuman impact on coastal landscape systems
Glaciated Landscapes
Topic overviewThe glacier as an open systemClimate change and the glacier budgetGlacier movementTypes of ice mass and their distributionGlacial weathering and erosion processesMacro-scale erosional landformsGlacial transport and depositional landformsFluvioglacial landformsSuites of landforms in glacial landscapesPeriglacial processes and ground icePeriglacial action of water and windGlacial change over different timescalesGlacial environments and human activity
Tectonic Hazards
Topic overviewThe internal structure of the EarthMechanisms of plate movementDivergent and conservative plate marginsConvergent margins and subductionHot spots and the global distribution of tectonic hazardsThe hazard profile and measuring magnitudeTypes of volcano and styles of eruptionPrimary volcanic hazardsSecondary volcanic hazardsImpacts of volcanic activity at different scalesContrasting volcanic eruptionsEarthquake characteristics and seismic wavesEarthquake hazards and ground behaviourTsunami processes and impactsContrasting earthquake eventsRisk, vulnerability and human factorsMonitoring, prediction and warningMitigation, response and the hazard management cycle
Changing Places
Topic overviewWhat gives a place its characterFlows and connections that shape placesMeaning, perception and attachment to placeHow places are representedEconomic restructuring and the Clark Fisher modelDeindustrialisation and social inequalityThe service economy and its impactsThe knowledge economy and clustersRebranding rural placesManaging change in rural placesRebranding urban placesManaging change in urban placesComparing a home place with a contrasting placeHow place change affects people's lives
Water and Carbon Cycles
Topic overviewThe water cycle as a global system and mass balanceGlobal water stores and residence timesCryospheric processes and sea-level changeDrainage basin inputs, stores and outputsFlows within the drainage basinRiver regimes and their controlsStorm hydrographs and hydrograph shapeAir uplift, cloud formation and precipitationExcess runoff and floodingDeficit in the water cycle and aquifer rechargeThe global carbon cycle and its storesCarbon pathways between land and the atmosphereCarbon transfers involving the oceansCarbon stores in biomes and land-use changeChanging carbon stores in peatlandsRising atmospheric carbon and its impactsFeedback within and between the water and carbon cycles
Global Migration
Topic overviewGlobalisation and a shrinking worldClassifying and mapping migrationCauses of international economic migrationConsequences and management of economic migrationRefugee movements and internal displacementRural-urban migration in developing countriesSuperpowers and global hub citiesMigration policy and public debate in the UKManaging refugee crisesInformal settlements in developing cities
Global Governance of the Oceans
Topic overviewSupranational institutions and global governanceLaws and agreements governing the oceansStrategic value of the oceans and maritime securityShipping, cables and illicit flowsSovereignty over ocean resourcesManaging marine environmentsOcean pollution and its managementGovernance across scales: an ocean case study
EcosystemsContemporary theme
Topic overviewThe value of ecosystems to peopleThe distribution of global biomesEcosystem structure, energy flow and productivityNutrient cycling in contrasting biomesMeasuring and threatening biodiversityConserving biodiversitySuccession and local ecosystemsThe Arctic tundra biomeSustainable use of the Arctic tundra
Economic Growth and Challenge: IndiaContemporary theme
Economic Growth and Challenge: ChinaContemporary theme
Development in an African ContextContemporary theme
Energy Challenges and DilemmasContemporary theme
Weather and ClimateContemporary theme
Fieldwork and Geographical Skills
Tectonic Hazards
Tsunami processes and impacts
- 2 things to know
- AS Unit 1 and A2 Unit 4
Overview
Two causes of tsunami other than earthquakes, typical open-ocean speed and wavelength for a tsunami and what happens to a tsunami as it approaches the shore.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Why was the Indian Ocean death toll so high in 2004?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Define a tsunami.
Model answer
A tsunami is a series of very long waves generated by the sudden displacement of a large volume of water, usually by vertical movement of the sea bed.
- 2
Which type of plate margin generates most tsunami, and why?
Model answer
Subduction zones, because the leading edge of the overriding plate is dragged down and then snaps upwards in a megathrust earthquake, lifting the whole column of water above it.
- 3
What are two causes of tsunami other than earthquakes?
Model answer
Submarine or coastal landslides, and the collapse of a volcanic flank or caldera.
- 4
Why is a tsunami barely noticeable in the open ocean?
Model answer
Its energy is spread through the entire depth of the water, so the wave may be less than a metre high even though it carries an enormous amount of energy.
- 5
State a typical open-ocean speed and wavelength for a tsunami.
Model answer
Speeds of the order of 700 to 800 km h⁻¹, with wavelengths that can exceed 100 km.
- 6
Explain what happens to a tsunami as it approaches the shore.
Model answer
Friction with the shallowing sea bed slows the front of the wave, the wavelength shortens and the energy is squeezed into a smaller depth of water, so the height of the wave increases sharply.
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