hazards Flashcards
define natural hazard
a perceived event that threatens people, the built environment and the natural environment. natural disaster only become hazards when a vulnerable population becomes exposed to it (deggs model)
how can you categorise hazards and examples
geophysical (land processes)- earthquakes, volcanic eruptions, landslides, tsunamis
atmospheric (climatic processes)- tropical storms, droughts extreme hot or cold weather, wildfires
hydrological (water processes)- floods, avalanches, storm surges
define disaster
hazardous event that caused unacceptably large numbers of fatalities and/or overwhelming property damage, UN defines as 10+ people being killed and 100+ people being affected
define risk
likelihood that humans will be affected by the hazard
define vulnerability
how susceptible a population is to the damage caused by a hazard
define hazard perception
how we view and process information about a hazard
factors affecting hazard perception
- wealth - richer people can have better provisions in place to not being badly affected
- religion- some people see hazards as being in God’s will
- education- more education means they have better understanding of the risks or hazards, and how to mitigate against
- past experience- people in hazard prone areas will know how to act
- personality- some fear hazards others may find them exciting and interesting
human responses to hazards
fatalism- view where people cannot influence the outcome and nothing can be done to mitigate against it
adaptation- attempts to live with the hazard and reduce their levels of vulnerability, like earthquake proof buildings
prediction- use last research to know the warnings of a hazard and help prevent major damage
prevention- ways of weakening the system as it approaches the land like seeding clouds
mitigation- strategies to lessen the severity of the hazard
risk sharing- pre arranged measured and public awareness to reduce the impacts on property and life, like through evacuation responses
what is parks model of human response to hazards and how can it vary
-describes a sequence of three phases following a hazard event
- model works as a control line and varying the steepness can show more catastrophic hazards with a slower response time
different stages of parks model
relief stage- immediate local response like food and medical services, immediate appeal for foreign aid
rehabilitation stage- services restore, temporary shelters food and water distributed
reconstruction stage- restore the area back to normal, rebuild new infrastructure
evaluation of parks model
+ useful to pinpoint the different kinds of response needed at different times
+ deepen understanding of responses
- does not take into account inequalities of development
- does not take into account varying capacity to response
- too general and not specific enough with the different magnitudes of hazards
- differences with climate change
stages of hazard management cycle
mitigation- minimise the impact of future disasters like building flood defences
preparedness- planning how to respond to a hazard like putting in warning systems
response- how people react when a disaster occurs like emergency services
recovery- getting the affected area back to normal
characterises of a hazard
- frequency- distribution of a hazard through time
- distribution- spatial coverage of a hazard
- magnitude- size of a hazard
- intensity- power of a hazard
features of inner core
- solid ball of iron and nickel
- very hot due to pressure and radioactive decay
- 6000C
features of outer core
- iron nickel
- less pressure so the metal can melt and it is semi molten
features of mantle
- thickest layer (2900 km)
- mainly solid rock
- very top layer is semi molten magma known as asthenosphere
- lithosphere is between mantle and crust and is where tectonic plates lie
features of continental crust
- 30-70km thick
- light so doesn’t sink
- known as SIAL due to larger amounts of silica and aluminium
- not created or destroyed
features of oceanic crust
- 5-10 km thick
- made of basalt
- constantly being destroyed and replaced
- heavy and dense so sinks below continental crust
- known as SIMA as it made of silica and magnesium
what did wegener suggest about how the continents once were
used to he one giant continent called pangea, which split into the continents we have today
geological evidence for plate tectonic theory
- continents vaguely fit together
- evidence of similar ancient glacial deposits in south america, antarctic and india
- similar rock type and structures along northern scotland and eastern canada
biological evidence for plate tectonic theory
- fossils found in india are comparable to those in australia
- fossil remains of mesosaurus found in southern africa and eastern south america
- identical plant fossils found in coal deposits in india and antarctica
what is palaeomagnetism
- discovery that earths polarity reverses on either side of the mid-atlantic ridge at regular intervals
- oceanic crust got older with distance from the middle of the ridge, and was mirrored on both sides
what is sea floor spreading and explain the process
- tectonic plates diverge and magma rises up to fill the gap, and cools to form new crust
- over time the new crust is dragged apart so more crust can form, as the sea floor gets wider
- however, crust is being destroyed elsewhere accommodate for new crust forming, and acts in a constant cycle
how can plates move
- convection currents
- ridge push or gravitational sliding
- slab pull
explain convection currents
- heat from earths inner and outer core heats the mantle, which rises upwards
- this cools and as it falls it drags the lithospheric plate with it
