paper 1, section a, challenge of natural hazards Flashcards
what are natural hazards?
a natural event that has a social impact
what are geological/tectonic hazards?
an extreme natural event in the crust of the earth that pose a threat to life and property
what are atmospheric hazards?
they occur as a result of processes in the atmosphere
what are some examples of atmospheric hazards?
- rain
- lightning
- drought
- snow
- hurricanes
- tornadoes
- wind
what category does flooding fall under?
not atmospheric or geological - hydrological
what are some examples of geological hazards?
- volcanoes
- landslides
- mudflows
- avalanches
- earthquakes
what factors affect risk?
- urbanisation
- poverty
- climate change
- farming
how does poverty affect risk?
poverty may force people to live in areas at risk
e.g. in Lima in Peru or Caracas in Venezuela there is a shortage of housing means people have had to build on unstable slopes prone to floods and landslides
how does climate change affect risk?
in a warmer world the atmosphere will have more energy leading to more intense storms
e.g. places may become wetter with an increased risk of flooding or drier and prone to droughts and famines
what are the two types of tectonic plates?
oceanic plate/crust
continental plate/crust
how are the two types of plates different?
oceanic plates are thinner and denser whereas continental plates are thicker and less dense
what mechanisms drive plate movement?
- they move due to convection currents which are currents of heat
- gravitational sliding which includes two mechanisms
what are the two mechanisms of gravitational sliding?
ridge push and slab pull
what is ridge push?
it happens at constructive plates; two plates are pushed apart by the injection of new magma
what is slab pull?
it happens at destructive margins where gravity acts upon the thicker, denser plate = sinks under its own weight
what happens at destructive/convergent plate boundaries?
- where the plates meet, a deep ocean trench is formed
- the dense oceanic plate subducts below the less dense continental plate
- friction between the plates creates strong earthquakes
- the subducted oceanic plate melts, creating less fluid magma (high viscosity)
- eruptions from the steep-sided composite volcanoes are often violent and explosive
what happens at constructive/divergent plate boundaries?
- magma forces its way up to the surface
- when the magma breaks through the crust it can cause small earthquakes
- upon reaching the surface it forms volcanoes
- the magma is hot and fluid (low viscosity) and results in broad, flat shield volcanoes
what happens at conservative/transform plate boundaries?
- friction between these plates causes earthquakes
- earthquakes happen as stresses build up gradually over many years
- they can be very destructive as they occur near the earth’s surface
- there are no active volcanoes at this tectonic plate margin
when and where did the earthquake occur in Nepal?
April 2015, in Gorkha
when and where did the earthquake occur in Italy?
April 2009, in L’Aquila
what was the magnitude of of the earthquake in Nepal?
7.8
what was the magnitude of of the earthquake in Italy?
6.3
how many deaths occurred due to the earthquake in Nepal?
8,841 (19 on Mount Everest)
how many deaths occurred due to the earthquake in Italy?
308