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Flashcards in Natural Hazards Deck (38)
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What is the inner core made of?

Iron and nickel


What is an example of a destructive plate boundary?

South America: Mazda plate is subducting under the South American plate to form the Peru Chile trench and the Andes


What is an example of a constructive plate boundary?

The mid Atlantic ridge: the Eurasian plate and the North American plate are moving apart


What is an example of a conservative plate boundary?

The Pacific plate is moving faster but in the same direction as the North American plate on the west coast of the USA (i.e. the San Andreas fault)


What is an example of a collisional plate boundary?

The Indian plate and the Eurasian plate are colliding to form the Himalayas


What is the Richter scale?

A measurement for the amount of energy released by an earthquake. It doesn't have an upper limit and it is logarithmic (a 5 is 10x more powerful than a 4)


What is a hotspot?

An area where the mantle is really hot so volcanoes form even though it may not be a plate boundary (i.e. Hawaii)


What are the primary impacts of earthquakes? List 6

Collapsing buildings and bridges
People injured or killed by debris
Infrastructure damaged - roads, railways, ports and airports
Electricity cables damaged
Telephone poles destroyed
Underground sewage systems damaged


What are the secondary impacts of earthquakes? List 8

Leaking gas ignited - fires
People left homeless
Physiological problems
Lack of sanitation and limited water supply - diseases spread
Difficult to get emergency vehicles through
Businesses damaged - unemployment - negative multiplier effect


Why are the impacts of earthquakes more severe in LEDCs? Explain 4

Poor quality housing is destroyed more easily
Poorer infrastructure makes it harder to distribute aid
They don't have much money to protect themselves or to react quickly
Healthcare is often worse so people die from treatable injuries if there aren't enough supplies


Why do people live in places where earthquakes happen?

They have friends and family there
They are employed in the area
They are confident of government support
People don't think severe earthquakes will happen again


How can you reduce the impacts of earthquakes? Explain 5

Prediction - use previous data, detect tremors
Building techniques - reinforced concrete, energy absorbing foundations
Planning - fire breaks, training emergency services, plan evacuation routes, avoid building on prone areas
Education - how to evacuate, how to make a survival kit
Aid - from governments or organisations


Why do people choose to live near volcanoes? List 3

Fertile soil from minerals from ash and lava
Tourist attraction - boosts local economy, jobs available
Source of geothermal energy


What are the primary impacts of volcanic eruptions? List 5

Buildings and roads are destroyed by lava and pyroclastic flow
People are killed by falling rocks and pyroclastic flows
Crops are damaged
Water supplies are contaminated
People, animals and plants are suffocated by gases


What are the secondary impacts of volcanoes? List 8

Lahars - flooding, more deaths, injuries
Psychological impacts
People left homeless
Shortage of food from damaged crops
Roads blocked so aid is hard to distribute
Businesses are damaged leading to unemployment
Sulphur dioxide released causes acid rain


How can the impacts of volcanic eruptions be reduced? Explain 5

Prediction: small earthquakes, released gas, changes in shape - GPS monitoring
Planning: firebreaks, trained emergency services evacuate routes, hazard mapping
Building techniques: strengthen so they don't collapse under ash, lava diverted using barriers
Education: survival kit, what to do if there is an eruption


What areas of the world are most at risk from drought? List 5

North Eastern Africa
the Sahel
Southern Africa
the Middle East


What are the climatic conditions that cause droughts?

Changes in atmospheric circulation - makes annual rains fail
High pressure weather systems can block depressions


What are the primary impacts of droughts? List 4

Vegetation dies
People and animals die of dehydration
Aquatic animals because rivers/lakes dry up
Soil dries out and is eroded by wind and rain


What are the secondary impacts of droughts? List 7

Animals/humans die from starvation
Soil erosion increases which can lead to desertification
Conflicts over supplies
Dust storms
Loss of jobs (I.e. at farms)


What are the human activities that make drought worse? Explain 2

Over grazing - reduces vegetation, causes erosion
Excessive irrigation - depletes rivers and lakes so there's less water and causes salinisation


How can you reduce the impacts of droughts? Explain 5

Prediction - monitoring rainfall, measuring soil moisture so you can prepare (ration water, move people)
Farming techniques - growing drought resistant crops (millet, olives), irrigating more effectively (drip irrigation)
Water conservation - in homes, using water butts
Increase water supplies - wells, reservoirs
Aid - emergency aid, aid to fund development projects


Which techniques used to reduce drought impacts may not be sustainable? Explain 3

Wells can deplete water supplies
Reservoirs can reduce water downstream
Emergency aid is expensive and isn't a long term solution


When and where do hurricanes form?

In the east pacific from June to October
In the Atlantic from August to October


When and where do cyclones form?

In the Indian Ocean (North from October to November, south from December to March)


When and where do typhoons happen?

The eastern Pacific - May to December and willy willies (south) from January to March


What conditions are needed for a tropical storm to form? 2

Sea water 26.5°C or higher
Between 5° and 30° north or south of the equator - too near equator then coriolis effect is too weak, too far and it's too cold


What are the characteristics of tropical storms? 5

In the northern hemisphere they spin anti-clockwise and move northwest
They are hundreds of kilometres wide
Usually last between 7 and 14 days
The eye can be 50km across and inside it is low pressure
Travel at around 15kmh but wind speeds can reach 120kmh


How are tropical storms formed?

Ocean temperatures warm to 26.5°C
Water evaporates and warm air rises and condenses to form clouds creating low pressure near the water
Since warm air moves to lower pressure (cold air) the air keeps flowing up to create clouds and rain
Air is ejected at the top and it goes round the sides and down to form the eye


What are the primary impacts of tropical storms? 9

Buildings and bridges are destroyed
Rivers and coastal areas flood
People drown, get injured or are killed by debris
Roads, railways, ports and airports are damaged
Electricity cables and telephone poles and cables are destroyed
Sewage overflows and can contaminate water supplies
Crops and livestock are damaged
Heavy rain makes hills unstable causing landslides
Beaches are eroded and coastal habitats are damaged