GCSE Natural Hazards Flashcards
(12 cards)
What is a natural hazard?
Any natural event that has the potential to endanger human life, the economy and property
What is an atmospheric hazard?
A hazard created in the atmosphere by the movement of air and water,
e.g Hurricanes, Lightning
What is a tectonic hazard?
A hazard created by the movement of tectonic plates
e.g Volcanoes Earthquakes Tsunamis
What are water based hazards
A hazard created by rivers, sea or oceans
e.g Floods
What is a biological hazard
Any biological substance that poses a threat to the health of people
e.g Covid-19, Malaria
Factors affecting natural hazards
Natural factors - things like rock type in an area during a earthquake - hard/soft or the height of the land hit by a tsunami can impact the effects
Population density - the greater the number of people in an area the more people affected by a disaster
Magnitude - the size/power of the event massively affects the impact it has emg how powerful the earthquake
Frequency - if a hazard keeps on happening in an area people won’t get the time to recover, or if people have rebuilt things after a disaster and then it happens again, it’ll be very expensive
Level of development - how well built buildings are, infrastructure healthcate etc, responses
Time - if it occurs when people are asleep they will be less prepared
Preparations - if a place is well prepared it can reduce the impact of the hazardous event
Accessibility - if the area is remote (difficult to get to) or thr weather conditions and aftershocks prevent safe search and rescue efforts then the impacts will be greatly increased
Evidence for tectonic theory
Continental Fit
Mountain Chains
Geology (rock type)
Fossil matching
Two types of crust
Oceanic Crust (denser, younger, heavier, beneath the ocean)
Continental Crust (less dense, older, lighter, beneath the land)
What are epicentre, focus and seismic waves
Epicentre - closest point to the Focus on land, Vibrations are felt most
Focus - centre of earthquake, where pressure is created and where the plates snag
Seismic waves - vibrations where the pressure is released
Describe constructive plate boundary
This is when plates move away from eachother
It is formed by:
Convection currents happen in the Mantle, pushing the oceanic crust apart. This creates earthquakes
This creates a gap which is filled by hot magma, creating new crust as the magma cools down
Creates earthquakes and volcanoes but low magnitude
Example is mid Atlantic ridge
The process is repeated eventually forming a volcano due to Convection currents
Describe destructive plate boundary
This is when plates move towards each other
Convection currents in the Mantle cause the Oceanic plate above to move towards the continental plate. Since it is denser the Oceanic plate is subduction beneath the continental plate
The Oceanic plate melts as it is subduction into the Hot Mantle. The plates may also build up pressure in the subduction zone causing earthquakes when the pressure is released. Eventually fold mountains are formed as the ground is folded upwards
The pressure on the continental plate causes cracks to happen. Magma rises up the cracks, expanding and going upwards. It rises up the mountain and erupts.
This creates high magnitude earthquakes and volcanoes
Describe conservative plate boundary
This is when plates rub past eachother
Convection currents in the Mantle cause the plates to move past each other (any plates)
Friction builds up as the plates move past each other
The plates snag past each other as the pressure builds up creating earthquakes
This creates high magnitude earthquakes, but not volcanoes
