Hazards
Concept of a hazard
Natural hazard = event which are perceived to be a threat to people, the built environment and natural environment. It has the POTENTIAL to affect humans. Occur in physical environments of atmosphere, lithosphere and hydrosphere
Natural disaster = hazardous event that causes unacceptably large numbers of fatalities and overwhelming property damage
Natural hazard becomes a disaster if 10+ people die, 100+ people affected, there is a declaration of a state of emergency, request for international assistance
Categorising hazards:
geophysical - caused by land processes e.g. earthquakes, volcanoes, landslide, avalanche etc.
atmospheric - caused by climate processes e.g. tropical storms, wildfires
hydrological - caused by water e.g. flooding
risk = exposure of people to a hazardous event presenting a potential threat to themselves their possessions and the built environment in which they live
risk increase over time due to increasing population:
building shanty towns on unstable tropical slopes
urbanising volcanic zones
living in active seismic areas
living in coastal areas susceptible to tropical storms and tsunamis
why do people put themselves at risk:
economic benefits
farming, tourism, mining, geothermal energy
personal preference
wealthy people
unpredictable nature of hazards
perception
urbanisation
lack of alternatives
poverty and lack of space - low income families are forced to build their slum house on a slope at risk of landslides
increasing risk due to land use change
e.g. deforestation increased risk of landslides
vulnerability = the potential for loss. This varies geographically, over time and among different social groups (varies over time and space)
Model of vulnerability and risk:
Perception of hazards:
Fatalism
a view of a hazard event that suggests that people cannot influence or shape the outcome, therefore nothing can be done to mitigate against it. People with such an attitude put in place limited preventive measures
Adaptation
people believe that they can prepare for and survive an event by predicting, prevention and protection
Fear
people feel so vulnerable to an extent that they feel so vulnerable to an event that they can no longer face living in the areas and move away to areas unaffected by the hazards
Factors affecting perception of hazard: Wealth
Increasing vulnerability
developing countries cities are growing far too rapidly leading to increased building in marginal areas e.g. low lying coastal areas, hillsides
Decreasing vulnerability
developed countries can afford technology needed to develop effective prediction and management techniques
developed countries can afford to build physical defenses to natural hazards
developed countries can train emergency services effectively
developed countries can educate locals on what to do during hazard event
Management of natural hazards:
Responses can come from individuals, local community, national governments, international agencies
Resilient communities are more able to effectively manage natural hazards
Integrated risk management
identification of hazard
analysis of risks posed
prioritising risks that are most serious
implementing a risk reduction plan
developing public awareness
maintaining and reviewing the entire process
= ongoing cycle of development and improvement
Risk is managed by:
Prediction
effective monitoring of hazards can allow for prior warning to be issued
Prevention
unrealistic but is possible in some circumstances e.g. flood defenses
Protection
protecting people and possessions/property from the impact of the event
Key components to hazard management:
governments teaching people to change their attitude and behaviour to natural hazards - decreasing vulnerability
community preparedness which involbes educating public on evacuation procedures, providing emergency medicine and food supply, construction of emergency shelters
modifying the losses which involves insurance pay out for any damages and economic losses in developed countries, international aid in developing countries
Successful management schemes:
cooling lava flows in Iceland with sea water
dynamite to divert lava flows on mt etna
Park model:
Shows changing quality of life through different phases of disaster
Hazard management cycle:
Plate tectonics
Earths structure
Continental crust:
mainly granite (SIAL - silicon, Aluminum, oxygen)
upper layer of earths crust and forms continental land masses
less dense (lighter)
30-70km thick
over 1500 million years old
Oceanic crust:
mainly basalt (SIMA - silica, magnesium, oxygen)
lower layer of earths crust and is found beneath the ocean
more dense (heavier)
5-10km thick
less than 2 million years old
Mantle:
largely composed of silicate rocks rich in iron and magnesium
widest section of the earth 2900km thick
upper mantle - rigid and together with crust forms lithosphere
middle part of mantle (asthenosphere) is in a semi-liquid state due to heat and pressure
lower part of mantle (mesosphere) - solid
mantle becomes denser the deeper it goes
temperatures near core reach 5000 degrees C
high temperatures near core believed to be responsible for generation of convection currents
separated from core by the Gutenburg Discontinuity (2900km below surface)
Core:
approximately size of mars
start about 2900km down - centre is 6350km down
most dense part of planet - 4x denser than crust
core temperature over 6000 degrees C
outer core is semi-molten - mostly iron
inner core is solid
Lithosphere - crust and upper mantle, where tectonics are found
Mesosphere - 3rd layer of atmosphere, between stratosphere and thermosphere
Asthenosphere - upper layer of mantle, where convection occurs
Gutenburg discontinuity - 2900km below earths surface, change is seismic waves
Moho discontinuity - boundary between crust and mantle, 10-12km below oceans
Inner core - innermost layer of earth, solid ball
Outer core - liquid layer between inner core and mantle
Mantle - between crust and core
Crust - outer most layer of rock
Continental crust - thick part of crust, forms land masses, old
Oceanic crust - thinner part of crust, underlies oceans basins, young
Tectonic theory
Continental drift: plates moving apart
evidence for continental drift
apparent fit of continents
continents fit together like a jigsaw
rock and mountain correlation
identical rock and mountain structures found on either side of ocean
paleoclimate data
coal has been found in cold regions and past glacial marks found in warm areas
fossil correlation
identical fossils found on opposite sides of ocean e.g. Mesosaurus fossils found south America and Africa
How plates move:
slab pull
as slab subducts the stress is transferred back up through brittle rock in lithosphere to the plate at the surface, pulling it down by slab pull
ridge push
hotter mantle rock flows up to fill the space - creating positive buoyancy and lift the ridge
as the new crust cools over time it becomes more dense and slides away laterally which pushes the plate apart by ridge push
convection currents
heat rises, cooler magma sinks
subduction zones in cooler areas
heat rising moves plates apart
Plate margins
15 plates make up earths crust
Constructive (divergent) margins:
2 oceanic plates move apart (mid ocean ridges created)
2 continental plates move apart (rift valleys created)
Ocean ridges:
when 2 plates pull apart there is a thinner, weaker zone in the crust and an increase in heat near surface - hotter expanded crust forms ridge
e.g. mid Atlantic ridge
volcanic activity occurs along ridge - creates submarine volcanoes (sometimes rise above sea level e.g. Surtsey Island - near Iceland)
Submarine volcanoes have fairly gentle sides because of lower viscosity of basaltic lava (thinner lava so can flow a long way before it cools)
eruptions are fairly frequent but gentle
as new crust forms and spreads, transform faults occur at right angles to the plate margin - parts of spreading plates on either side of these transform faults may be moving at different rates, leading to friction and ultimately to earthquakes (shallow focus)
Rift valleys:
occur at constructive margins in continental areas - 2 continental plates pulling apart
heating and up-doming of crust leads to fracturing and rifting
as sides of rift move apart, central sections drop down to form rift valleys
largest = great east african rift valley - 4000km long and 50km wide
has horsts and grabens - graben = fallen blocks
Destructive (convergent) margins:
oceanic-continental
denser oceanic plate forced under lighter continental one - process = subduction
as oceanic crust descends, friction with overlying continental crust builds up and causes major earthquakes
as plates converge, continental plate is uplifted, buckles and is folded to create chains of fold mountains - compression continues and can become symmetrical forming a recumbent fold - further compression can make the middle sections so thin it might break creating a nappe
the collision bends the plate downwards forming a deep ocean trench
melted oceanic plate rise in form of plumes - forming volcanic eruptions
eruption of magma takes place offshore - a line of volcanic islands known as island arc can appear e.g. Japan
friction leads to stress/tension that can build up and by released as deep focus earthquakes
benioff zone = further the rock descends, the hotter the surroundings become - this together with heat generated from friction, begins to melt oceanic plate into magma
ocean trench - e.g. peru-chile trench
oceanic-oceanic
one plate forced under the other = subduction
crust that is subducted may be marginally denser or is the one moving faster
ocean trenches and island arcs are main features e.g. Mariana trench
continental-continental
similar density so neither will be subducted
plates collide and are folded up into fold mountains
they have deep roots in lithosphere
no volcanic activity
can trigger shallow focus earthquakes
orogenesis = process of a fold mountain forming
Conservative margin
2 plates move parallel to each other - they can move in opposite directions or same direction but at different speeds
no creation or destruction of crust
no subduction therefore no volcanic activity
as they move past each other friction builds as plates snag on one another and parts of the fault line lock and pressure builds - stress energy released and sends shock waves through earths crust (earthquakes)
e.g. san andreas fault line (california) - pacific plate moving at faster rate than north american plate
Hot spots
Not all volcanic activity can be related to present day active plate margin
Hot spots do not fit with plate tectonic theory
radioactive decay within earths core generates hot temperatures - if decay is concentrated then hot spots will form around core - these hot spots heat the lower mantle, creating localised thermal currents where plumes of magma rise vertically
how do they form:
magma is lighter than solid lithosphere and rises up
plumes burn through lithosphere create volcanic activity on surface
where crust is thin above a hot spot provides further opportunity for magma to escape as volcanic eruption
lava builds up over time eventually creating an island above present sea level
as hot spot remains stationary, movement of overlying plate results in formation of a chain of volcanoes
e.g. Hawaii
Volcanic hazards
Volcanoes found along ocean ridges, rift valleys, subduction zones and hot spots
vulcanicity - all volcanic activities related to magma being forced into the crust (usually at plate margins)
hazards with volcanoes:
submarine, coastal or island eruptions may cause tsunamis
pyroclastic flows of superheated gas, ash and pumice destroy life and property
dust emissions can seed torrential rainstorms causing dangerous wet ash and mud lahars
volcanic melting of snow creates lahars
ash fall ruins crops and machinery, pollutes the air and disrupts
flooding from lava flows block and divert rivers
benefits to volcanoes
lava and ash weather quickly create fertile soils
volcanoes make great tourist attractions along with geysers, hot springs and boiling mud = economic
igneous rocks contain valuable minerals such as gold, silver and diamonds
volcanic Sulphur is used in pharmaceuticals and agrochemistry industries
extinct volcanoes make great defensive sites e.g. Edinburgh castle
volcanic ash absorbs solar energy so temperatures are reduced
lava creates new land
igneous rocks make great building materials e.g. granite
hot rocks can generate geothermal power
How to measure magnitude of volcanoes:
measured on Volcano Explosivity Index (VEI)
relative scale = enables explosive volcanic erruptions to be compared to one another
VEI measures on volume of material ejected, height of eruption column, style and type of eruption, duration of eruption
as VEI increases, frequency decreases
Eruptions vary in form, frequency and type due to different types of plate margin, emissions and lava
types of magma:
basaltic - low silica, low viscosity, rich in minerals e.g. iron
andesitic - rich in iron, magnesium and calcium, higher silica and water content, more viscous, more acidic
rhyolitic - granite, very viscous, high silica content, high water content
constructive plate margins form shield volcanoes and produce effusive eruptions
destructive plate margins form composite volcanoes and produce explosive erruptions
Volcano classification:
fissure eruptions
cracks in the crust found at spreading ridges where tension pulls the plates apart allowing lava to spill out over a large area
basalt forms a large plateau, filling hollows other than building up into a typical cone shaped volcanic peak
columnar jointing produced by slow cooling of lava provides tourist attractions e.g. Giant Causeway
rifts and constructive plate margins
gentle eruptions
lava plateau
created by fissure eruptions
a wide area of flat featureless solidified lava that can be up to 1km thick covering large surface areas
multi layered because of repeated lava flows and occur where lava pours out of long fissures rather than a central vent, covering much larger areas with thick layers of magma
shield volcanoes
very wide volcano
built up slowly by accretion of thousands of flows of highly fluid lava that spread widely over a great distances and cool as thin, gently dipping sheets
lava also commonly erupt from vents along fractures that develop on flanks of cone
magma has very low gas content and is low in silica, allowing it to flow over large distances
hot spots and oceanic-oceanic destructive plate margins
gentle eruptions
composite cones
most common type found on land
classic pyramid shaped volcanoes consisting of layers of ash and lava that is usually andesitic
e.g. Mt Etna, Sicily
destructive plate margins (continental)
explosive eruptions
dome volcanoes
steep sided convex cones consisting of viscous lava
destructive plate margins (continental)
explosive eruption
ash cones
formed by ash, cinder, tephra and volcanic bombs ejected from central crater
sides are steep and symmetrical in a concave shape
destructive and constructive plate margin
explosive eruptions
calderas
when gases have built up beneath a blocked vent, it results in a catastrophic eruption that destroys the volcano summit - this emphasises magma chamber and allows sides of volcano to collapse inward, leaving an opening several km in diameter
may form a lake within it
destructive plate margin
very explosive
IMPACTS OF VOLCANOES
Primary:
Tephra
solid material of varying grain size - ranging from volcanic bombs to ash. All ejected into atmosphere
Pyroclastic fallout
material that has been ejected from a volcano during an eruption and falls back down to the ground
when it consists of mostly ash = ash fallout
ranges from large rocks to ash
heavier material deposited first (closer to volcano), small particles carried further
high velocity
Lahars
Lava flows
vary depending on lava
low viscosity lava travels long way faster
high viscosity lava travels shorter way as its slower (thicker) - easier to evacuate
both destroy everything in path by burning and burying
Volcanic gases
e.g. CO2, CO, sulphide
Nyos Crater 1986 - carbon dioxide emissions killed 1700 people
Secondary:
Lahars
melted snow and ice as a result of eruption combined with volcanic ash forms mud flows that move down course of river valleys at high speeds
destroy everything in path by flooding and burying
Flooding
eruption melts glaciers and ice caps e.g. Iceland
Acid rain
emit gases which combine with water vapour
can damage ecosystems
Monitoring and predicting - use seismic equipment to detect warning signs of events
Protection - designing buildings that will withstand hazard
Planning/preparation - identifying and avoiding places most at risk. Preparing for any effects and how to reduce effects
Evacuation - reduces injury and life loss
Restricting access to area - stops people getting too close = reduce death
Diverting lava - saves lives, reduces injury, reduces damage to roads, ports and businesses
Improved building design - reduces poverty/business damage, thus reducing injury, death, loss of jobs and lost to economy
Campaigns to increase awareness - encouraged to keep emergency kits in home = prepared = reduce death/injury
Volcanic hazard maps - educate people about risk areas, reduce injury and death by ensuring locals are prepared
Seismic hazards
Earthquakes
more violent earthquakes at destructive plate margins
more frequent earthquakes at conservative plate margins
earthquakes occur because of stress and energy building up between plates - released as seismic waves
3 focuses: shallow (0-70km), intermediate (70-300km), deep (300+km)
Richter scale: how magnitude of earthquakes is measured
2 types of seismic wave:
body waves: fastest moving
primary - fastest and travel longitudinally creating compressional stress in direction of movement. Travel through the earth with refraction
secondary - slower and transverse the direction of movement creating sheer stress. Only travel through solids
surface waves
move across surface of crust and produce most damage
love waves = transverse across line of direction of seismic wave. move objects from side to side
Rayleigh waves = move in longitudinal direction in same line of direction as the seismic wave. move objects vertically
Why does damage vary:
population density - more potential for loss of life and property damage
earthquake depth - shallower focus = more damage
building design - HICs better designed to withstand earth shaking - limits loss of life and damage caused
earthquake strength
geology - rock type, solid rocks = less damage
IMPACTS
primary:
ground shaking
severity depends on magnitude, depth, distance from epicenter and geology
causes buildings collapsing
rupturing
shaking can rupture the ground - visible breaking and displacement of earths surface
causes a major risk to engineered structures e.g. damns, bridges, nuclear power plants
secondary:
fires
resulting from broken gas pipes and collapsed electricity transmission systems
landslides
slope failure as a result of ground shaking
soil liquefaction
occurs when shaking of silts, sands and gravels causes them to lose their load bearing capacity and begin behaving like fluids
buildings and other structures may sink into ground
tsunamis
ocean waves with extremely long wavelengths, generated by earthquake tremors
Reducing risk of earthquakes
seismographs used to measure levels of activity (foreshocks may occur)
earthquake proof infrastructure - withhold shaking
earthquake drills carried out in schools
emergency kit in every home
Tsunamis
generated by shallow focus underwater earthquakes, eruptions
in open ocean tsunamis have very long wavelengths and low wave height and travel very quickly (700km/h)
on reaching shallow water they increase rapidly in height
1st warning for coastal populations is wave trough in front of tsunami, which causes a reduction in sea level known as drawdown
tsunami can reach heights of 25m
90% of tsunamis generated within pacific basin and are associated with tectonic activity
effects depends on
height of waves and distance they’ve travelled
length of event that caused tsunami
extent to which warmings can be given
coastal physical geography, both offshore and in coastal area
coastal land use and population density
Management
3 P’s
Storm hazards
Topical storms are intense low pressure weather systems that develop in tropics. Usually measure 200-700km in diameter
Begin with an area of low pressure resulting in surface hating into which warm air is drawn in a spiraling manner. These small scale disturbances can enlarge into tropical depressions with rotating wind systems and they continue to grow into a much more intense and rapidly rotating system
Measured on Saffir-Simpson scale
Conditions needed:
oceanic location with sea temperatures above 27 degrees c - provides a continuous source of heat in order to maintain rising air currents
ocean depth of at least 70m - moisture provides latent heat, rising air causes the moisture to be released by condensation and continuation of this drives the system
a location at least 5 degrees north or south of equator = Coriolis force can bring about the maximum rotation of air
low level convergence of air in lower atmospheric circulation system - winds have to come together near the centre of the low pressure zone
rapid outflow of air in upper atmospheric circulation - this pushes away warm air which has risen close to the centre of the storm
Impacts depend on intensity of storm, speed of movement, distance from sea, physical geography of coastal area, preparations made by community, warnings and community response
Impacts:
winds
often exceed 150km/hr
high winds cause structural damage to buildings (collapse), roads and bridges etc.
can bring down electricity transmission lines and devastate agricultural areas
huge amounts of debris flung about are a serious threat to peoples lives
heavy rainfall
can exceed 300mm
brings about severe flooding, landslides and mudslides
storm surges
high sea levels result when wind driven waves pile up and ocean heaves upwards as a result of lower atmospheric pressure
can have devastating effect on low lying coastal areas such as river deltas where the flooding can extend a long way inland
cause majority of deaths
agricultural areas can suffer for a long time as soil contaminated by sea water
Managing tropical storms
Prediction
data from geostationary satellites and land and sea data and round the clock surveillance of tropical storms that have the potential to become hazards by aircraft - compared with computer models so path can be predicted and people warned to evacuate
high economic risk with evacuation and false alarms lead to people becoming complacent and refuse future advice so essential that warnings are correct - in USA evacuating coastal areas costs 1 million dollars per km of coastline
not always possible to give more than 12 hours warning - in poorer areas communications are poor so insufficient for proper evacuation
1997 - tropical cyclone warning in Bangladesh allowed for evacuation of over 300000 people = death toll below 100
Prevention
cloud seeding causes more precipitation = weakening tropical storm system
Protection
predicting landfall will enable evacuation to take place
emergency services on full alert
homes are strengthened to withstand strong winds
cyclone/hurricane drills
land use planning can identify areas at greatest risk and certain types of development can be limited in such areas
sea walls and flood barriers built and houses put on stilts
Preparedness
practicing evacuation plans to save lives, money, property etc.
poorer areas suffer more because land use planning, warning systems, defenses, infrastructure and emergency services are inadequate = higher death toll
richer countries have planning systems in place, warning systems, better defenses and infrastructure and emergency services that are much more comprehensive and better prepared
Wildfires
Types of wildfire
ground fires - fires that burn organic material in soil. Slow burning fire. They smoulder and burn for a long time
surface fires - burn on surface of ground. The most common fire. Burn dry leaf litter, broken twigs and branches. Easiest to control
crown fires - burn with huge flames and has intense heat. Burn from tree top to tree top and spread very quickly with wind and heat particularly on steep slopes. Most intense and most difficult to control
factors affecting wildfires
wind - influences speed at which fire spreads, direction in which fire travels, intensity of fire (wind provides more oxygen), likelihood of spotting (burning pieces of leaves twigs and bark that the wind carries ahead of the fire - causing new ‘spot’ fires to ignite)
topography (slope) - fire will burn faster uphill, flames can easily reach more unburnt fuel in front of the fire, radiant heat preheats the fuel in front of the fire (making it more flammable), for every 10 degree slope the fire will double its speed, by increasing speed the fire also increases in intensity becoming even hotter, opposite applies to fire travelling downhill
aspect of land - aspect is the direction that a slope faces. The direction a slope faces determines how much radiated heat it will receive from the sun, slopes facing south to southwest will receive the most solar radiation so are warmer than north facing slopes. Warmer slope = lower relative humidity, higher temperatures and rapid loss of moisture
temperature - higher temperatures absorb moisture from fuels and make them conductive to catch fire. Areas with lots of sun and higher temperatures tend to be dry and have more fire events
humidity - how much water the air can hold. Drier the air, the faster the vegetation dries out which intensifies a blaze. Consistent rain key for fire suppression. Humidity saps large amounts of energy from wildfires so high humidity lowers spread - when humidity above 15% risk is low. Humidity varies in day - lowest in early afternoon = more wildfires then
fuel - spread of wildfires depends on fuel composition. Trees and vegetation with lots of moisture tend to slow down fires than dry vegetation. Additionally some vegetation with high oil and resin make fires burn with more ease
times and seasons - el nino events lead to increased wildfires. Also more fires in summer as heat makes fuels drier and provides richer oxygen
space between fuel - if more fuels in close proximity = wildfires spread more easily
Causes of wildfires:
Natural
2 things needed: ignition source and fuel
lightning main cause, other causes = lava flows
climate and weather affect frequency of electrical storms, frequency and duration of droughts which the vegetation and litter has opportunity to accumulate and dry out, type of vegetation growing in an area
Human
arson
falling power lines
discarded cigarettes
children playing with matches
camp fires not put out propely
sparks from machinery
broken glass left in vegetated areas (magnifies sun)
agricultural fires which get out of hands
Distribution of wildfires
key regions: Australia, USA, Canada, Southern Europe
most susceptible areas have dry vegetation and lightning strikes, as well as areas susceptible to drought
fires can clear vegetation and aid new seed germination, stimulate the growth of certain plants and rid area of insects and some parisites
IMPACTS:
primary
loss of crops, timber and livestock
forest fires can have a huge impact in timber producing areas - loss of trees takes many years to replace
in USA it has been estimated that over $10 million per day spent facing fires
loss of life
many fires are events from which people can get out of the way however some fires move so fast that people can be trapped
Australia bushfires 2009 - 173 people died
loss of property
urban expansion means urban rural fringes are susceptible e.g. LA
cost of damage and fighting fires can run into hundreds of millions of dollars
causes homelessness
release of toxic gases and particulates
large scale air pollution
largely caused by slash and burn practices (especially in Indonesia)
loss of wildlife
damage to soil structure and nutrient content
intense heat at ground level
destroys many soil nutrients and lead to alteration in soil structure
loss of crops
secondary
evacuation
emergency shelters/accommodation will have to be found along with food etc.
increased flood risk
loss of vegetation = less interception = increased flooding
loss of jobs
cost of rebuilding
cost of future preparedness and mitigation
review laws/advice for using countryside for leisure
disruption to transport
reduction in water quality and air quality
impact on tourism
weather changes temporarily
Managing event:
Preparedness, prevention, mitigation
managing vegetation
controlled burning to get rid of litter and creating firebreaks in vegetation in advance rather than during the event
managing built environment
increasing gap between houses and vegetation and incorporating more fire resistant methods in construction
being well insured
in wealthier countries, residents are urged to take out insurance against fire damage
modelling
studying ways in which fires behave with computer simulations in order to comprehend and predict fire behaviour
education
e.g. Smokey Bear educating Americans - 70% can recall fire safety message
average number of hectares lost to wildfires has fallen from 54 million in 1944 to 16.5 million today
warning systems
lookout towers and air patrols
community action
Australia 1983 - 47 dead, 2000 homes and cost $200 million
community education program established - community fireguard which assisted people in developing fire survival strategies
dealing with event as it happens
fighting fires - spraying water and chemicals
retardants
slow pace of wildfire
after fighting fires
replanting trees
wildfire prevention
cut down some trees - reduce fuel to reduce crown fire spreading
clear dead leaves and branches - little dry fuel
spark arrester on chimney to stop sparks - no embers to start fire and less heat
removing anything blocking driveway - escape route and fire service have easy access to fire
move firewood away from home - reduce fuel around house
cut grass often - reduce fuel around house, harder for surface fires to spread to contain fire
cut back branches - reduce fuel to reduce crown fire spreading
use materials that do not burn easily - no fuel and property doesn’t catch fire - decrease homelessness
Case studies
VOLCANOES
BIG E, ICELAND (HIC)
iceland on constructive plate margin but also a hot spot so a lot of volcanic activity
normally eruptions are effusive (mild)
on average iceland experiences erruption every 4 years
1/3 of all lava erupted been in Iceland in last 10000 years
85% of housing in Iceland is heated by natural geothermal heat
Iceland = one of least polluted cities in world
20th March 2010: Big E erupted
Local impacts:
Jokulhlaups (glacial floods)
blocked roads, flooded farmland, cut electricity, local water supplies contaminated
Mudflows
ash covered farmland (5.5cm) = crops destroyed, harm farm animals
2 tourists died
800 people evacuated from homes and farms
global impacts:
no fly zone imposed across europe due to ash - largest shut down since WW2 - airlines losing £130 million a day
impact was felt as far as Kenya - 5000 workers laid off after vegetables left rotting in airports
Europe lost £2.5 billion of GDP due to eruption
Teachers, government and others got stuck abroad
less noise pollution from major airports and 2.8 million tonnes less CO2 emitted during period
EARTHQUAKES
TOHOKU, JAPAN (LIC)
destructive plate margin
11th March 2011
measured 9 on richter scale
long term responses:
immediate responses:
factors affecting damage caused
primary impacts
18000 dead/missing
tsunami triggered and swept 10km inland causing total devastation to an area of 500km2
buildings collapsed but many are eq proof
200000 buildings damaged
electricity cut off in over 6 million homes
1 million left with no clean drinking water
power cut at Fukishima power plant - radioactive materials escaped causing local radioactivity levels to increase up to 40000x - long lasting health impact
Fukishima dam flooded
secondary impacts
500000 people forced to live in shelters
2 million people left homeless as a result of tsunami
rail and road disruptions
lack of clean water
power cut at Fukushima power plant - radioactive materials escaped causing local radioactivity levels to increase up to 40000x - long lasting health impact
total cost to rebuild was £185 billion
Responses:
$300 billion project to reconstruct infrastructure (LT)
UK sent 70 medical support team to Japan and 2 search dogs
China sent $167000 in aid
Japan red cross sent 230 emergency teams to worst affected areas to provide medical support
Shelter box NGO sent 1500 boxes of aid (tents, bottled water etc.)
100,000 Japanese soldiers deployed
Pakistan government sent 2 cargo planes carrying 24 tonnes of relief goods including food and water
shelters set up in schools for those who lived close to nuclear power plant
STORMS
HURRICANE KATRINA (HIC)
95% of deaths came from drowning
levees were built on soft peat = flood defenses failed
1300 dead
800000 homeless
TYPHOON HAIYAN, PHILIPPINES (LIC)
8th November 2013
category 5 ‘super typhoon’
Philippines is vulnerable because:
low literacy rate - less people can read typhoon warnings
GNI per capita - almost 10x less than America, less development of buildings and less preparation, response after is worse
between the tropics = warm, deep oceans
Tacloban = shape of land around it funnels storm surges towards Tacloban
EFFECTS OF TYPHOON HAIYAN
Primary
schools damaged and destroyed (social)
90% of Tacloban city destroyed (social)
600000 people displaced (s)
falling trees destroyed homes, businesses and killed people (s)
2000 missing (s)
26000 injured (s)
6300 died (s)
phone lines and internet cut off (s)
5m storm surge with waves up to 15m (en)
Tacloban flooded with up to 20 feet of water (en)
195mph winds (en)
1.1 million tonnes of crops destroyed - over 1 million farmers and 600000 hectares of agricultural land affected (en)
1 million homes damaged/destroyed (s)
forests and habitats destroyed when trees uprooted (en)
30 000 fishing boats destroyed (en/ec)
4.4 million homeless (s)
Secondary
flooding caused roads to be blocked and people were stranded and isolated (s)
hospitals flooded and destroyed which meant it was difficult to treat survivors and those open were overwhelmed increasing death toll (s)
water supply contaminated and water pipes broken - no clean water (s)
ferry services and flights cancelled for weeks, flowing down aid efforts and reducing tourism (s/ec)
some survivors of typhoon were wounded by debris and these wounds become easily infected in warm, wet and filthy conditions (s)
people without access to food and water - starving (s)
6 million lost jobs (ec)
14 million affected (s)
$20 billion cost to philippines - 5% of its GNP (ec)
oil tanker ran aground causing 800000 litre oil leak - damaged 10 hectares of mangroves (en)
agriculture and fishing industries destroyed - cost $3.6 billion to rebuild (ec)
rice is staple food of philippines - crops destroyed costing $53 million (ec)
more deaths due to spread of disease (s)
WILDFIRES
Australia bushfires
MULTIHAZARDOUS ENVIRONMENT
Philippines:
UNFINISHED