Living With The Physical Environment - Natural Hazards Flashcards
Natural Hazards
A natural event that poses as a threat to humans and/or property
Atmospheric hazards
Tornadoes
Droughts
Geological hazards
Earthquakes
Volcanoes
Flooding hazards
Avalanches
Tsunami’s
Hazard risk
Chance of being affected by a natural hazard
Factors affecting risk
Urbanisation
Poverty
Farming
Climate change
Earthquakes
A sudden or violent movement within the earth crust
Volcano
An opening in a planets crust through which molten rock, hot gases, and other materials erupt
Convection currents
Heat-driven cycles that occur in the mantle
Constructive plate margins/boundaries
Two plate boundaries move apart
As a gap appears magma forces its way upwards breaking through the overlying crust
This causes earthquakes
E.g. Azares
Destructive plate margins/boundaries
Two plates are moving towards each other
The oceanic plate is subducted beneath the continental plate
Friction is built up and released through an earthquake
The continental plate melts, forming magma that breaks through the surface to form a steep-sided volcano
E.g. Andes
Collision plate margins/boundaries
Two plates are moving towards each other
The two plates collide and the crust uplifts forming folded mountains
This process causes earthquakes
E.g. San Andreas Fault
Conservative plate margins/boundaries
Two plates move past each other
Friction causes earthquakes
E.g. The Himalayas
Nepal case study - Facts
Date - 25/4/2015
Magnitude - 7.9
Plate boundary - destructive
Nepal case study - Primary effects
Social - 9000 died, 20000 injured, 8 million (1/3 of the population) affected
Economic - cost $5 billion, 50% of shops destroyed
Environmental - no power or water supplies
Nepal case study - Secondary effects
Social - avalanche in Langtang region left 250 people missing
Economic - roads blocked
Environmental - landslide/avalanche killed 19 people
Nepal case study - Immediate responses
Roads repaired
Landslides cleared
1/2 million tents provided
Nepal case study - Long term responses
30000 migrated
Repairs to Everest base camp
7000 schools repaired
Chile case study - Facts
Date - 27/2/2010
Magnitude - 8.8
Plate boundary - destructive
Chile case study - Primary effects
Social - 500 died, 12000 injured, 800000 affected
Economic - cost $30 billion, 220000 homes destroyed
Environmental - no power, no water supplies
Chile case study - Secondary effects
Social - coastal towns destroyed by waves
Economic - 1500km of roads destroyed, remote communications cut off
Environmental - Pacific countries were hit by tsunamis
Chile case study - Immediate responses
Field hospitals
$60 million for emergency shelters
Power + water restored
Chile case study - Long term responses
4 years to fully recover
Economy was rebuilt
Housing reconstruction plans
Why do people choose to live in hazardous areas?
Poverty - cannot afford to move (V+E)
Location - want to live near family or friends (V+E)
Fertile soil and minerals - agricultural benefits, rocks = construction materials for buildings (V) (Used in Iceland - case study)
Geothermal energy - provides 90% of energy/electricity (V) (Used in Iceland - case study)
Monitoring - scientists can accurately tell when a disaster is going to happen through seismometers and animal behaviour (V+E)
Frequency - volcanoes don’t erupt everyday, large earthquakes are rare (V+E)
Reducing the risk - Earthquakes
Monitoring - earthquakes cannot be predicted
Prediction - no clear warning signs
Protection - walls are reinforced in steel, shock absorbers to absorb shaking, tsunami walls (protect people and important buildings e.g. nuclear power station)
Planning - use hazard maps as they the areas most likely to be affected and they can be evacuated
Reducing the risk - Volcanoes
Monitoring - remote sensing (detect heat), gas (instruments detect gas), hydrology (measurement of gases dissolved in water)
Prediction - scientific monitoring
Protection - use earth embankments, use explosives to divert lava
Planning - use hazard maps to show the likely areas to be affected so people can be evacuated
