P1. Section A Flashcards
what is a natural hazard?
a natural event that has the potential to cause damage, destruction and death
- must have social and economic impacts
what is a hazard risk?
the chance or probability of being affected by a natural event
what are 7 examples of natural hazards?
volcanoes, earthquakes, tropical storms, heat waves, droughts, tornadoes and wildfires
what are the 2 subsections natural hazards are split into?
- weather hazards (atmospheric hazard)
- geological hazards (tectonic hazards)
what are tectonic hazards caused by?
caused due to movements of the plates
- w.g earthquakes, volcanoes and tsunamis
what are atmospheric hazards caused by?
by weather & climate
-e.g flooding and wildfires
what is the other name for weather hazards?
atmospheric hazards
what is the other name for geologic hazards?
tectonic hazards
what are 3 human factors affecting risk?
- population density
- level of development
- poverty
what is population density?
how many people live in a certain area
-more people = more deaths
what are 5 physical factors affecting risk?
- time of day
- length of time since the last hazard happened
- urbanisation
- climate change
- farming
Tectonic plate move due to…
convection currents
how does earthquakes create convesction currents
what is the area where the plates melt, then turn to magma and rises called?
the magma chamber
is the oceanic crust thinner or denser?
thinner
what happens to the oceanic crust
is thinner and denser so subducts
- is constantly being destroyed and replaced at plate boundaries
describe the continental crust
- thick and less dense
- is older than oceanic ( over 1500 millions years old)
- can’t be renewed or destroyed
what happens at the destructive (collision) margin?
- 2 continental plates collide
- there’s no subduction because they are the same density
-they collide and and push up forming fold mountains
what happens at constructive plate margins
2 plates move apart
- magma rises up to fill the gap
- new crust is formed as magma rises to the surface
- this means that some places the sea floor is still growing
this is called sea floor spreading
what happens at conservative plate margins?
- plates slide past each other and lock causing friction
- the pressure builds up and causes shockwaves which causes earthquakes
what happens at destructive plate margins?
- continental meets oceanic plate
-oceanic subducts under continental - plate starts to melt due to friction
- magma builds in the chamber and forced to rise through gaps in the continental plate
- gravity pulls oceanic plate into mantle, dragging plate away from constructive margin
what human activity can cause earthquakes
mining
- therefore may not occur on tectonic plates.
what is diverging?
when 2 plates move apart
what is converging?
when 2 plates move together
what is slab pull?
where older, denser, tectonic plates sink into the mantle at subduction zones
what are the 4 ways to reduce risk
- monitoring
- prediction
- protection
- planning
what are 2 reasons why people live in areas at risk of volcanic hazards
- fertile soil –> grow lots of crops
- geothermal energy
- tourism