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the challenge of natural hazards (tectonic hazards (plates (plate margins,…
the challenge of natural hazards
tectonic hazards
plates
core = iron and nickel
mantle moves slowly - semi molten
continental crust
thicker, less dense
oceanic crust
thinner, more dense
plates move due to convetion current in mantle
plate margins
destructive - towards
oceanic under continental - ocean trenches + volcanoes
2 continental - mountain ranges
constructive - away
magma rises to fill gaps = new crust
conservative - sideways
same way at different speeds or different ways
crust not created or destroyed
volcanoes
destructive
oceanic plates into mantle and destroyed
pool of magma forms
magma rises through vents
erupts onto surface = volcano
constructive
magma rises through gap
form over hotspots
eruptions emit lava and gas
ash covers land
pyroclastic flows block sun
(superheated ash, rock, gas)
effects and responses
primary effects
buildings and roads destroyed by lava, pyroclastic flows, ash collapses buildings
people injured
crops destroyed and water contaminated
volcanic gases = suffocation
secondary effects
mudflows / lahars - valcanic material + water
flooding - hot rock melts snow
transport networks blocked - aid not get through
homelessness
tourism disrupted
ash = more fertile land
long recovery
immediate responses
evacuation
provide temporary supplies + shelter
treat injured
rescue
foreign gov + charities - support
tech companies - disaster response tools
long term responses
repair and rebuild
reconnect
improve evacuation plans
boost economy - tourism
earthquakes
tension
builds at boundary
destructive / conservative - plates stuck
constructive - cracks in plate
jerk past eachother sending
shockwaves
shockwaves spread from focus - here waves are stronger and cause more damage
epicentre
measured by moment magnitude scale
energy released
logarithmic
7+ major damage
effects and responses
primary effects
buildings and bridges destroyed
people injured/ killed
roads and airports damaged
supply and communication networks destroyed
secondary effects
trigger landslides + tsunamis
gas leak = fires
homelessness
shortage of clean water
difficult aid access
businesses damaged
expensive repairs
immediate responses
rescue and recover bodies
put out fires
temporary shelters and supplies
foreign gov + charities send aid
tech companies - disaster response tools so people confirm safety and damage recorded
long term responses
rehouse and rebuild
repair bridges and buildings
reconnect supply networks
improve building regulations
initiatives to help economic recovery
management
monitoring
seismometers and lasers monitor earth movement
warning system
tiny earthquakes, escaping gases, change in volcano shape
prediction
earthquakes not reliably predicted
forecast areas where will occur
volcanoes predicted if well monitored
time to evacuate
protection
buildings designed to absorb earthquakes energy
existing buildings strengthened
automatic shut off for gas + electricity to prevent fires
planning
future developments avoid areas most at risk
emergency services trained and prepped
people evacuated
gov plan evac routes
emergency supplies stockpiled
why do people live in areas of high risk?
confident of support
always lived there
employed there
fertile ground attracts farmers
tourist attraction - employees live in area
natural hazard
natural process causing disruption to humans
hazard risk factors
type
frequency
magnitude
populated area
coping capacity
weather hazards
atmospheric circulation
(winds)
winds are caused by difference in air pressure as a result of difference in temp
move from high to low pressure
warm air rising = low pressure
cool air falling = high pressure
equator sun warms earth
low p = clouds and rain
rises and cools, moves 30 N/S
cool air sinks
high p = cloudless and low rain
moves back to equator or pole
winds towards equator = trade winds
-blow NW in S hemisphere and SW in N
-at equator, trade winds meet and heated
blow towards poles = westerlies
SE in S and NE in N
60 N/S warm air meets cold
warmer air less dense so rises = low p
air moves towards poles / equator
at poles cold air sinks = high p
back to equator as surface winds
affects earths climate and weather
tropical storms
formation
warm moist air rises and condenses
release energy = storm power
rising air = low pressure so increases surface winds
move west
earth rotation deflects wind path = spin
storm gets stronger due to energy from warm water
so wind speeds increase
lose strength when move over land or cooler water
occur between 5-30 N/S equator
warm enough sea
northern hemisphere in late summer / autumn
rise in global temperatures
more places have tropical storms
oceans at 27C for more of the year
higher temp = stronger so more damage
27C +
low difference in wind speed
features and structure
eye
50km across
descending air
low pressure
high temp
light winds
no clouds or rain
eyewall
spiralling rising air
strong winds and rain
low temperature
at the edges
wind speed drops
clouds smaller and more scattered
temp increases and rain less intense
last 7-14 days
spin anticlockwise in N
clockwise in S
coriolis force
effects and responses
primary effects
bridges and buildings destroyed
flood - people drown / injured
roads, railways airports damaged
electricity damaged - cut off supplies
sewage overflow = contaminate water
secondary effects
people left homeless
shortage of clean water = disease
roads blocked - aid not access
businesses damaged - unemployment
shortages of food
more settlements = greater effect
immediate responses
evacuation
rescue / recover bodies
temporary shelters / supplies
foreign gov support
tech companies - disaster response tools
long term responses
repair buildings / rehouse
improve forecasting techniques
promote economic recovery - tax breaks
improve building regulations
management
prediction
use radar, satellite and aircraft data to monitor storms
computer models calculate prediction path
gives time to evacuate and protect
planning
future developments avoid risk areas
emergency services train and prepare
gov plan evacuation routes
protection
buildings designed to withstand storms
put on stilts - safe from flood
reinforced concrete
flood defences along rivers / coasts
reduce destroy of buildings
= fewer killed, made homeless, unemployed
UK weather hazards
rain
too much in short time = flood
businesses close, disrupt transport, damage homes
= high cost
wind
strong winds = damage properties + transport
strongest in coastal + upland areas
uprooted trees - damage forests
snow and ice
injuries and deaths
schools and businesses shut
economic impacts
damage crops
hailstorms
driving dangerous
damage property and crops
thunderstorms
heavy rain, lightning and strong winds
summer in SE
death and fires
heatwaves
heat exhaustion and breathing difficulties
disrupt transport - roads melt etc
tourism increases
economic impacts
drought
low water supply - crop failure
rules to conserve water
more extreme weather
temperatures more extreme
raining more
major flooding occurs often
climate change
evidence
Quaternary period
most recent geological time period from 2.6m years ago to present day
before Quaternary, climate = stable and warmer
during Quaternary, glacial periods (100,000 yrs)
warmer interglacial periods (10,000 yrs)
last glacial period ended 15,000 yrs ago and earth warming
global warming
sharp rise in global temperatures over last century
ice and sediment cores
one layer forms each year
scientists drill into sheets - ice core
analyse gases trapped - tell temperature
antarctica 400,000 yrs
organisms in ocean sediment 5m yrs
tree rings
new ring each year
rings thicker in warm, wet
thickness = what climate like
count ring to find age
10,000 yrs
pollen analysis
preserved in sediment
identify and date = which species alive
know conditions plants live in now
compare pollen to show if climate similar
temperature records
1850s temp measured by thermometer
reliable but short term
historical records - further back
causes
natural factors
orbital changes
orbit can vary between ellipsis and circle
every 96,000 yrs
affect solar radiation therefore temp
-orbital changes may have caused glacial and interglacial cycles
volcanic activity
material into atmosphere
some particles reflect suns rays = cooling
release co2 - not enough to cause GW
cause short term changes to climate
solar output
suns output changes in short cycles (11 yrs +)
when output reduced, climate cools
scientists think not much affect on climate change
human activites
scientific consensus - human activities are causing global warming by making greenhouse effect stronger
greenhouse effect
gases (co2 and methane) absorb outgoing heat
essential to keep planet warm
too many gases mean too much energy trapped = warm
burning fossil fuels
co2 released when burnt
e.g. coal, oil, natural gas, petrol
cement production
made from limestone containing carbon - co2 released
farming
produces methane
livestock
flooded fields (rice paddies)
deforestation
plants remove co2
convert to organic matter
chopped - stop taking in co2
co2 released when trees burnt
effects
environmental
glaciers shrink + ice sheets melt
water stored as ice returns to oceans
= rising sea level
shrinking sea ice = loss of habitats
rising sea levels = lowland flooded, increase coastal erosion, loss of habitats
species declining - coral reef bleaching
changing precipitation patterns
decrease biodiversity
same species in high latitudes
habitats destroyed - adapted species become extinct
people
deaths due to heat increase
deaths due to cold decrease
areas impossible to inhabit
areas too hot and dry
low lying coastal areas lost/floodded
lead to migration and overcrowding
change in water supply / availability
lead to political tensions (rivers cross boarders)
crops suffered but higher latitude crops benefit
lower crop yield increases malnutrition + ill health
weather more extreme
more money spent on predictions reducing impacts and rebuilding
management
mitigation
reduce causes
carbon capture
CCS reduce emissions from fossil fuel burning power stations
capture co2 and transporting it - storage
planting trees
increases co2 absorption
alternative energy productions
replace fossil fuels with renewable
reduce greenhouse gases
international agreements
most countries agreed to monitor + cut greenhouse gas emissions by signing international agreement Kyoto protocol
each country set target (UK 12.5% by 2012 - met target by reducing it to 22%)
EU set to cut emissions by 20% by 2020
adaption
adjusting to effects
changing agricultural system
plant new crop types - more suitable
biotechnology create new crop varieties more resistance to extreme weather
managing water supply
water meters - discourage use
collect rainwater and recycle waste water
coping with rising sea levels
physical flood defences and warning systems
LICs raised buildings and raised flood shelters