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
reduce risk: what is monitoring?
using scientific equipment to detect warning signs of events such as volcanic eruption
reduce risk: what is prediction?
using historical evidence and monitoring, scientists can make predictions about when and where a tectonic hazard may happen
reduce risk: what is protection?
designing buildings that will withstand tectonic hazards
reduce risk: what is planning?
identifying and avoiding spaces most at risk and practising what you would do if a tectonic even happened
what are 8 features of earthquake resistant buildings?
- roof covering the area to prevent pedestrians from shattered glass
- shock absorbers in foundation to absorb seismic waves
- deep foundations into solid rocks
- several emergency stair case
- cross bracing to provide extra support to the frame
- weights on the roof to counterbalance shaking
- large open areas for evacuees and emergency services to gather
- strong steel frame with girders interlinked
what is an example of monitoring?
Hurricane watch which monitors the North Atlantic
- ppl are advised and can plan/ evacuate —> decreases amount of deaths
what is an example of protection?
houses built on stilts:
- reduces chances of flooding
shutters on windows:
- pedestrians won’t be shattered with glass
what is an example of prediction?
Hurricane warning in the North Atlantic
- ppl know if a hurricane will happen so can evacuate
what is an example of planning?
evacuation drills - USA preparedness week
- means organisation and less panic
what is the definition of weather?
day to day changes in the conditions of the atmosphere
what is the definition of climate?
an average weather over a period of time (e.g 30 days)
what is the definition of extreme weather?
weather that is significantly different from the usual weather pattern
give 3 examples of climate.
tropical, temperature, polar
give 3 examples of weather.
drought, rain, sunny, fog
give 8 examples of extreme weather
thunderstorms, prolonged rainfall, drought, extreme heat, heavy snow, extreme cold, strong winds and thick fog
what is global atmospheric circulation?
the circular movement of air around the earth to try and balance the temperature
what is lattitude?
how far north and south you are from the equator
why is the equator warmer than the the poles?
because solar radiation is spread over a greater angle this means the solar radiation is less concentrated. Furthermore solar radiation travels through more atmosphere to get to the poles this means more solar radiation is reflected or absorbed before reaching the earth’s suface
what is the energy that is released from the sun called?
solar radiation
does the equator have a greater or smaller energy from the sun?
greater
what weather condition forms during high pressure?
anticyclone conditions
what weather conditions form during low pressure?
cyclonic conditions
what is anticyclone conditions
what does wind blow from?
high to low pressure
what are cyclonic conditions
why does air rise at the equator?
because air is heated so becomes less dense and rises
what is warm air that rises called?
low pressure
is there little or a lot of rainfall in high pressure?
little
why is it the coolest at the poles?
because the solar radiation is spread over a large surface area so is less concentrated
why do polar regions experience little rainfall?
because they experience high pressure so air is sinking not rising and condenses
what is storm surge?
winds push water –> deadliest aspect of a hurricane
what is a tropical storm?
a localised, very intense low- pressure wind system, forming over tropical oceans and with winds of huricane force
what are 4 conditions needed for hurricanes/ tropical storms to form?
- between 5 and 20 degrees north and south of the equator
- 27 degrees minimum ocean temperature
- 74 mph wind speed
- water needs to be at least 60m deep
what are hurricanes measured on?
saffir -simson scale
what is chloropleth map?
what are 2 advantages of chloropleth maps?
- visually appealing therefore easy to read
- Quick and easy to construct
what are 2 disadvantages of chloropleth maps?
- hard to get an accurate reading as the boundaries between the data are high
- makes generalisation/ estimations because not all areas would have had the same impact
what us hurricane watch?
advises that hurricane conditions are possible
What is hurricane warning?
advises hurricane conditions are expected and people should take immediate action
What is the cone of innacuracy?
prediciting the wrong path of Typhoon Haiyan
- The circumstances of the cone increases as it travels
