global hazards Flashcards
can earthquakes happen in all plate boundaries?
yes
what are the four main plate boundaries?
constructive, destructive, collision and conservative
How is friction an important factor in the build up to an earthquake?
Because the two plates catch on each other which causes the friction. This friction builds up until the rocks can no longer handle it then they jolt and move forward. This jolt is the earthquake and it releases energy through seismic waves
what are seismic waves?
vibrations generated by an earthquake
what is the focus of an earthquake?
the point where the ground moves, which can be at different depths within the plate
what is the epicentre of an earthquake?
the point on the surface of the land above the focus
what is a primary effect?
something that is directly caused by the disaster
what are examples of primary effects of earthquakes?
ground shaking, surface displacement, building and infrastructure damage, landslides
what are examples of secondary effects of an earthquake?
fires, human casualties, impact on economy, tsunami, aftershocks
what are four factors that change how strongly the ground shakes during an earthquake?
the strength of the earthquake itself, how deep the focus is, how far the location is from the epicentre and what the ground is made from
how does the type of rock change the effects of an earthquake?
softer rocks shake more easily and become fluid, but stronger rocks will withstand more stress before fracturing
what is liquefaction?
when rocks shake so violently that they turn into a liquid state, shockwaves cause deeper groundwater to rise to the surface and particles to shake together to become a fluid
what factors led to the Haiti earthquake being so deadly?
buildings were not built strong enough (densely populated - domino affect with houses collapsing on each other), city was close to fault line, lack of knowledge + preperation, emergency services problems, lack of warning systems
in a destructive plate boundary, are the two plates the same?
no, one of the plates is a continental plate and the other is an oceanic
in a constructive plate boundary, are the two plates the same?
yes, they are both continental plates
in a conservative plate boundary, are the two plates the same?
yes, they are both continental plates
in a collision plate boundary, are the two plates the same?
yes, they are both continental plates
what is a hot spot?
a large plume of hot mantle material rising from deep within the earth (a place where the magma rises up through the crust)
what is cause of earthquakes?
sudden movement along faults within the Earth
what are the hazards in a constructive boundary?
earthquakes, volcanoes can be made
what is the hazard in a collision zone?
earthquakes
what is the hazard in conservative boundary?
powerful earthquakes
what is subduction?
where the oceanic plate is forced underneath the continental plate
what plate margin does subduction occur in?
destructive plate boundary
what are the 4 main layers of the atmosphere?
thermosphere, mesosphere, stratosphere + troposphere
where does the hadley cell cell extend from?
from the equator to about 30-40* N+S
where does the ferrel cell range from?
from about 30-40* to 60-70* N+S
where does the polar cell extend from?
about 60-70* to 90* at the poles N+S
which cell is the largest?
the hadley cell
which cell is the smallest and weakest?
the polar cell
in simple terms, how does the hadley cell move?
blows down from tropical regions towards the equator, meeting the trade winds that go in an easterly direction, then the warm are rises and forms thunderstorms which the are then flows towards the higher latitudes where it becomes cooler and sinks over subtropical regions
is it true that the polar cell works in the opposite direction to the other cells?
no, the ferrel cell works in the opposite direction to the hadley and polar cells
how do the ferrel cells move?
it joins the sinking hadley cells and travels at low to mid latitudes where it rises towards the boarder of the polar cells. the air then flows back towards the low latitudes in the direction of the equator
which cell is responsible for the frequently unsettled weather in the UK?
the ferrel cell
how do the polar cells move?
the air sinks over the highest latitudes (N+S poles) and then flows out towards the lower latitudes
what happens to create high pressure?
cool, condensed air falls increasing the pressure on the earth’s surface as the cool air is subjected to warming so clouds evaporate
what happens to create low pressure?
warm air rises, so less pressure on the earth’s surface and as it rises, it cools and condenses to form clouds. the moisture in the clouds fall as precipitation
what weather is associated with low pressure?
high winds, warm rising air, cloud cover and precipitation
what weather is associated with high pressure?
moisture removed from air forms heavy rainfall at equator and clear skies and dry weather at the sub-tropics
what type of climate is there typically in the tropical climate?
humid - so hot and wet all year round
why is it humid in the tropical climate?
there is relatively low pressure because the air rises which leads to rainfall and thunderstorms due to the hadley cells meeting
what climate is there typically in the temperate climate and what are the summers and winter like?
usually cloudy with frequent rainfall. cool, wet winters + warm, wet summers
why do you get cloud and frequent rainfall in the temperate climate?
low pressure is created from the rising of the warm , subtropical winds which then cools and then condenses as it meets the cool polar front to form clouds and frequent rainfall
what type of climate do you typically get in the sub-tropical (desert) climate and what are the seasons like?
very dry climate with less than 250mm of rain a year. summer with temps between 35-40* and winters with temps between 20-30*
why do you get a very dry and hot climate at the sub-tropical climate?
the dry air sinks as the hadley and ferrel cells meet leading to high pressure
what type of climate do you typically get in the polar climate?
dry with icy winds with temps ranging between 0 (in summer) and -40 (in winter)
why do you get a dry climate with icy winds in the polar climate?
the cool air from the polar cell sinks which produces high pressure creating extreme cold temperatures
what are tropical storms?
intense low pressure systems
what is the coriolis effect?
the result of the earth’s rotation on weather patterns and ocean currents. it makes storms swirl clockwise in southern hemisphere and anticlockwise in the northern hemisphere
how is the Saffir-Simpson Hurricane Wind Scale used?
it is a scale from 1-5 which says how much damage will be / has been created. 1 being some damage and 5 being extreme damage
how warm do the oceans have to be for a hurricane to start to form?
over 27*
how is a hurricane created?
- the warm temps of the ocean (over 27*) cause hot air to rise which then cools to create big cumulus clouds
- the rising air creates low pressure at sea level so air with high pressure moves in to replace it by whirling into it
- this air then moves upwards which causes storm clouds to be pulled in by wind and for the storm to be pulled outward leaving a low-pressure funnel in the centre (the eye)
- the spinning circle drifts sideways due to trade winds
- this huge bundle of energy depresses the sea level under it causing a storm surge
what was typhoon haiyan classed as and why?
classed as a super typhoon because the wind speed got up to 196mph
where did typhoon haiyan form?
6* north of the equator in the north pacific ocean
what were the primary effects of typhoon haiyan?
storm surges (floods), strong winds + heavy rain
what were the secondary effects of typhoon haiyan?
homelessness, diseases + famine (starvation)
how many people were effected by typhoon haiyan?
11.5 million
how much economic damage was there estimated to be cause by typhoon haiyan?
$2.86 billion
how many people died due to typhoon haiyan?
at least 6,300
how many houses were destroyed and how many people were homeless due to typhoon haiyan?
130,000 houses destroyed and 670,000 people homeless
how much money was lost from farm damage after typhoon haiyan?
$85 million
how many tonnes of rice was lost in the Philippines due to typhoon haiyan?
130,000 tonnes
how many evacuation centres were set off as a response to typhoon haiyan?
1215 evacuation centres
how much did the UK alone send as a response to typhoon haiyan?
£50 million as well as sending HMS Daring over too
how did the government in the Philippines respond to the typhoon?
they deployed soldiers to restore law and order because there was widespread looting and violence
what were the main factors that made typhoon haiyan so devastating?
- the Philippines is an LIDC so the infrastructure is not stable enough to withstand such extreme weather
- there were 2 channels of warm air flowing into the typhoon which lead to wind speeds of up to 196mph
- there was low wind sheer (normally would stop or slow down the typhoon)
- storm surge was 5m causing waves of up to 15m
what are the conditions found during an El Nino event?
- weak trade winds so everything goes the other way
- warm water moves from west to east
- South America has low pressure + water water = more evaporation = more precipitation
- Australia has high pressure + cold water = less evaporation = less precipitation
what are the conditions found during an La Nina event?
the warm water currents and trade winds go from east to west like normal but with greater intensity
- Australia has low pressure + warmer water = more evaporation = more precipitation
- South America has high pressure + colder water = less evaporation = less precipitation
what is a drought?
when a region experiences below average precipitation for a prolonged period of time
what are the human causes for drought and how does it cause droughts?
- deforestation - reduces the soils ability to hold water
- excessive irrigation
- climate change leads to higher temps so more evaporation
- dam building deprives regions downstream water
- overgrazing exposes soil to erosion and limits its ability to hold moisture
what are the physical causes for drought and how does it work?
- when regular weather hazards have been disturbed
- El Nino brings descending air and high pressure over Australasia
- climate change leads to higher temps so more evaporation
the ITZ may not move as far as usual
what does ITCZ stand for and what is it?
Intertropical Convergence Zone is a low-pressure belt which encircles the globe around the equator. it is where the trade winds form northeast and southeast meet
how can the ITC lead to drought?
if it doesn’t move as far north or south to reach some of the driest areas, it won’t relive them from the dry conditions they have experienced for half a year so could lead to drought (less rain)
what are the impacts of drought?
famine, loss of agricultural jobs, wildfires (could lead to homelessness), hydroelectricity shortages + reduce tourism
how could a drought reduce tourism rates?
loss of natural beauty, swimming pools may be shut, might be a limit on water supply / usage
what caused the UK heatwave?
- low pressure in the UK and high pressure over Europe
- a heatwave had been declared in spain
- this allowed the southerly winds to draw in hot air from the high-pressure system that was over the central and southern europe
- lead to sweltering heat in the UK
what was a economic impact of the UK heatwave and was it positive or negative?
more people want to go outside so will spend money on local businesses which is positive
what were social impacts of the UK heatwave and was it positive or negative?
- speed restrictions were put on trains which lead to delays - negative
- elderly and small babies cannot regulate their heat very well so number of deaths increased - negative
what were the environmental impacts of the UK heatwave and were they positive or negative?
- there was a large fire which consumed about 30 acres of Thetford forest - negative
- it could lead to problems for farming as crops could die and animals could overheat and die - negative
what was the ‘Beat the Heat’ programme?
the government came up with it to promote how to stay safe in the heatwave
how did different stakeholders respond to the UK heatwave?
- speed limits were put on trains
- met office issued weather warnings during and in advance to the heatwave
- government implemented a hosepipe ban to save water which affected 7 million households
- free ice cream was given out
- cold showers for zoo animals
