Paper 1: Section A - Natural Hazards Flashcards
Natural Hazards, Tectonic Hazards, Weather Hazards, Climate Change. Case studies: Chile & Nepal, Typhoon Haiyan, Somerset Level Floods 2014
What is a natural hazard?
Natural event that has a huge social impact / environmental events threatening people.
What is a natural disaster?
A natural hazard that occurs and causes high levels of death, injury, damage, destruction or disruption.
Link between natural hazards and disasters:
Natural hazards are possible disasters.
4 hazards causing natural disasters mainly:
Flood, tropical storms, earthquakes, droughts
What are the two main categories of natural hazards?
Geological & atmospheric
What is a geological hazard? Name 3.
Caused by tectonic processes. E.g. earthquake, avalanche, volcano
What is an atmospheric hazard? Name 3.
Caused by weather and climate processes. E.g. long periods of low rainfall can cause drought. Also hurricanes and flooding.
What is hazard risk?
The probability that a natural hazard occurs.
What is hazard risk influenced by?
DEFORESTATION (increases chance of flooding), URBANISATION (more people so impacts increase, higher death toll), DEVELOPMENT LEVEL/POVERTY (more wealth can reduce impacts), CLIMATE CHANGE (more severe, distribution), FARMING (in dangerous areas)
What are the two types of crust? Which is more dense?
Oceanic (more dense) and continental (less dense)
Earthquakes and volcanoes are primarily found where?
Plate boundaries
Plate movement is driven by what?
Convection currents in the mantle
What happens at a constructive plate margin? Usually forms what kind of volcano?
2 plates moving APART. Lava from an underwater volcano. Causes mild earthquakes. Usually shield volcano (Mid-Atlantic Ridge)
What happens at a destructive plate margin? Usually forms what kind of volcano?
Plates move towards each other. Deep ocean trench formed. Oceanic plate subducted. Friction - strong earthquakes. Composite volcanoes as sticky magma. Nazca plate and South American plate.
What happens when there are 2 continental plates at a destructive plate margin?
Collision plate boundary. Neither are subducted. No volcanoes as no magma. Forms fold mountains. Powerful earthquakes. Himalayas.
What happens at a conservative plate boundary?
Plates moving past each other. San Andreas Fault, California. Different speeds or different directions. No volcanoes as no magma. Earthquakes when they slip.
What is an earthquake?
A sudden violent period of ground-shaking, caused by friction, pressures and stresses.
Describe the distribution of volcanoes:
Like earthquakes, most occur in belts along plate margins (Pacific Ring of Fire) but also at hot spots (Hawaii)
What is an effect?
A change as a result/consequence of a hazard.
What are the two types of effects? Give examples of each
Primary (direct result): destroy buildings, deaths.
Secondary (result of primary): tsunamis, landslides, fires.
What are the two earthquakes for the case study?
Chile 2010 and Nepal 2015.
Compare the GDP and HDI of Nepal and Chile.
Chile GDP 38/193 and HDI 41/187.
Nepal GDP 109/193 and HDI 145/187.
What was the cause of the Chile 2010 earthquake?
Nazca plate subducting under South American Plate.
What was the cause of the Nepal 2015 earthquake?
Indo-Australian plate colliding with the Eurasian plate.
What were the sizes of the Chile and Nepal earthquakes?
Chile: 8.8, shallow focus
Nepal: 7.9 VERY shallow focus.
What were some primary effects of the Chile 2010 earthquake? (deaths, injuries, total affected)
500 killed, 12,000 injured, total 800,000 affected.
Power, water and communications cut.
What was the damage cost of the Chile 2010 earthquake?
US$30 billion
What were some primary effects of the Nepal 2015 earthquake? (deaths, injuries, total affected)
9000 killed, 20,000 injured, 8,000,000 total affected
Destruction of buildings and infrastructure.
What was the damage cost of the Nepal 2015 earthquake?
US$5 billion
What were some secondary effects of the Chile 2010 earthquake?
landslides, costal towns devastated by tsunami, chemical plant fire near Santiago
What were some secondary effects of the Nepal 2015 earthquake?
Communities cut off by landslides/avalanches.
Avalanches Mt. Everest killed 19.
What are the two kinds of responses? Provide examples
Immediate responses: done straight away; search & rescue, keeping survivors alive with emergency aid.
Secondary responses: after a period of time; rebuilding and reconstruction, restore normal life, reduce future risk.
What were some short term responses to the Chile earthquake?
Emergency services acted swiftly.
International help for field hospitals, floating bridges.
Temporary repairs for Route 5 highway withing 24 hrs so aid can come from Santiago.
Power & water restored to 90% in 10 days.
National appeal raised US$60 million to build 30,000 shelters.
What were some short term responses to the Nepal earthquake?
300,000 migrated from Kathmandu.
Field hospitals set up.
Half a million tents for shelter.
Search & rescue teams especially helicopters on Mt. Everest.
NGOs provided overseas aid.
Social media used in search & rescue.
What were some long term responses to the Chile earthquake?
1 month later government reconstruction plan to help 200,000 households.
Strong economy reduced need for foreign aid.
Likely to recover fully in 4 years.
What were some long term responses to the Nepal earthquake?
Roads repaired, landslides cleared. Lakes emptied to avoid flooding.
1000s of homeless rehoused.
Damaged homes & 7000 schooled repaired.
Stricter building codes.
June 2015 international conference to seek financial aid.
Tourism re boosted.
Overall, how did the wealth difference reveal itself with regards to Chile and Nepal?
Chile wealthy and experienced so has a rapid and effective response. Nepal response hindered by poverty, depended on overseas aid.
Why do people live near places vulnerable to hazards?
Fertile soil
Minerals, e.g. gold, silver, diamonds
Geothermal energy
Buildings can be designed to withstand risk
Large hazards rare
Limited choice - money, food, family
Improvements in monitoring - effective warning & evacuation
No knowledge of the risk
How does Iceland benefit from tectonic activity?
Geothermal heating for 90% of buildings and generates 25% of electricity.
Tourism
Volcanic rocks used in construction.
What are the four main management strategies for tectonic hazards?
Monitoring, prediction, protection, planning
What is monitoring for tectonic hazards?
Using scientific equipment to detect warning signs of events. Seismometer to see ground deformation. Earthquakes hard to monitor.
What is prediction of tectonic hazards?
Using historical evidence (important for earthquakes) and monitoring to predict hazards. Allows for evacuation.
What is protection from tectonic hazards?
Designing buildings and infrastructure that can withstand hazards. E.g. earthquake-resistant construction.
What is planning for tectonic hazards?
Identifying and avoiding places most at risk and preparing people for emergency responses.
Risk assessment, hazard mapping
What is global atmospheric circulation?
The movement of air and gases around the Earth to balance the temperatures. Drives the world’s weather.
What are the atmospheric cells?
Hadley, Polar and Ferrel cells.
What direction do surface winds blow?
High (sinking air) to low (rising air) pressure.
What is the Corriolis effect?
The Earth spins on its axis. Points near the equator rotate on axis faster.
What weather is associated with high pressure?
30 degrees North/South
hot, dry desert
little rain
What weather is associated with low pressure?
Hot, humid at Equator
Heavy rain - tropical rainforests.
How does latitude affect climate?
Sun’s rays most concentrated at the equator and spread out at the poles so hotter at equator.
How does curvature (Earth is spherical) affect climate?
Seasons and corriolis effect.
Rays concentrated at Equator but spread out at poles as pass through larger layer of atmosphere.
How does air pressure affect climate?
Creates cells that circulate the air and transfer heat.
High pressure: air sinks. Winds move away.
Low pressure: air rises. Winds move towards.
What are the conditions for a tropical storm to form?
Ocean temperature above 27 degrees.
Light wind shear - clusters of thunderstorms.
Corriolis effect (Northern hemisphere spin anticlockwise)
Describe the structure of a tropical storm:
Eye: calm conditions, cool air sinks.
Eyewall: most intense, strong winds, thunder, lightning.
Edge: smaller thunderstorms, rain, strong winds.
How will climate change affect tropical storms?
Distribution: sea temperatures warmer in more places.
What scale is used to measure tropical storms?
Saffir-Simpson scale (1-5)
