GEOGRAPHY UNIT 1A challenge of natural hazards Flashcards
What are not counted as natural hazards?
extreme events which do not pose any threat to human activity eg. a drought in an uninhabited part of a desert
What are the 2 types of natural hazard?
- geological hazards caused by land and tectonic processes
- meteorological hazards caused by weather and climate
What are the factors that affect natural hazard risk?
- vulnerability
- capacity to cope
- nature of natural hazards
How does vulnerability affect natural hazard risk?
the more people that are in an area exposed to natural hazards, the greater the probability they will be affected by the natural hazard
How does capacity to cope affect natural hazard risk?
- better a population can cope with an extreme event, the lower the risk of them being severely affected
- e.g. HICs are better able to cope with flooding as they can afford to build flood defences
How does nature of natural hazards affect natural hazard risk?
- type, risk from some hazards is greater than others e.g tropical storms can be predicted and monitored, volcanoes not
- frequency, natural hazards that occur more often are more likely to carry a higher risk
- magnitude, more severe natural hazards tend to have the greatest effects
What are the primary effects of natural disasters?
the immediate impacts caused by the hazard itself
What are some examples of primary effects?
- buildings and roads destroyed
- people injured or killed
- crops or water supplies contaminated or damaged
- electricity cables, gas pipes and communication networks can be damaged, cutting off supplies
What are the secondary effects of natural disasters?
happen later on as a result of the primary effects
What are some examples of secondary effects?
- initial hazard can trigger other hazards
- aid and emergency vehicles can’t get through because of blocked roads
- shortage of clean water can spread disease
- food shortages can occur if crops are damaged
- country’s economy can be weakened
What are some examples of immediate responses?
- evacuate people
- treat the injured and rescue
- recover dead bodies
- provide temporary electricity and gas
- provide food, drink and shelter
- foreign governments or charities may send supplies or aid
What are some examples of long-term responses?
- repair homes and rehouse people
- rebuild buildings or roads
- reconnect broken electricity, water and communication connections
- improve forecasting, monitoring and evacuation plans
- improve building regulations so that buildings can withstand similar hazards in the future
- boost economic recovery
What are tectonic plates?
earth’s crust is divided into slabs called tectonic plates that float on the mantle
Difference between oceanic and continental plates?
oceanic:
- thinner
- more dense
continental:
- thicker
- less dense
Why are tectonic plates moving?
convection currents
What happens when an oceanic plate meets a continental plate?
- denser oceanic plate is subducted and destroyed creating gas-rich magma
- volcanoes and ocean trenches are formed
What happens when 2 continental plates meet?
ground is folded upwards creating fold mountains
What happens at a constructive plate margin?
- two plates are moving away from each other
- magma rises to fill the gap and cools, creating new crust
What happens at a conservative plate margin?
- when two plates are moving in the same direction along each other at different speeds
- or when two plates are moving sideways past each other
- crust isn’t created or destroyed
How is a volcano formed at a destructive plate margin?
- denser oceanic plate moves down into mantle where it melts
- a pool of magma forms which rises through cracks in the crust called vents
- magma erupts forming volcano
How is a volcano formed at a constructive plate margin?
magma rises up into gap created by plates moving apart which forms volcano
How are some other volcanoes formed?
parts of the magma that are really hot called hotspots
What happens when a volcano erupts?
- emits lava and gases
- some emit lots of ash which can cover land, block out sun and form pyroclastic flows
What are pyroclastic flows?
super-heated currents of gas, ash and rock