Hazards Flashcards
what is a hazard?
A hazard is a perceived event that threatens life and property.
They often result in loss of life/damage to the environment.
example of a natural hazard?
-Volcanic activity
-seismic activity
-tropical storms
ALL-CAUSE (DID) DEATH, INJURY, DISRUPTION
hazards pose danger to people, what have the population done to increase the danger of hazards?
-build shanty towns on unstable tropical slopes
-urbanise volcanic zones
-live in areas with active faults
-areas susceptible to hurricanes and tsunamis
what is fatalism?
a view that people cant influence the outcome, therefore do nothing to MITIGATE (reduce the impact of hazard)
reasons for people living in a high-risk environment?
-hazard events are unpredictable
-lack of alternatives (people cant uproot themselves from one place and move to another, giving up their homes)
-changing the level of risk (overtime the risk increased eg: deforestation = increased risk of flooding in the area and higher risk of landslides)
-cost/benefit: California is susceptible to earthquakes, however, the benefits of opportunity out way the costs.
-perception ( model of vulnerability)
HICs to minimise the impact of natural hazards
-building sea walls
-earthquake-proof building
-better emergency services
-better educated
different INFLUENCES in which a hazard is perceived
-socio-economic status (wealthier feel more prepared, this can be due to technological based solutions)
- level of education
-occupation
-religion, culture
-family and marital status
-past experience
-values, personality and expectations
people may perceive hazards in different ways?
Fatalism- acceptance, in some areas believing it is in gods hands. so actions usually concerning safety and losses are accepted and inevitable.
Adaptation- people prepare by prediction, prevention and protection.
fear- people are so scared they leave the area and move away to regions unaffected by hazards.
what is integrated risk management
often incorporates:
-identification of the hazard, analysis of the risks
-establishing priorities
-treating the risk and implementing a risk reduction plan
-developing a communication strategy
how can people use prediction as a way of managing a hazard
prediction- given warning. key thing is to improve MONITORING in order to give better predictions so warnings can be issued. (NATIONAL CENTRE IN FLORIDA, how prediction can depend on monitoring, through the use of info from satellites)
how does prevention manage a natural hazard
natural hazard this is very unrealistic although ideas of seeding clouds in potential tropical storms to cause more precipitation would weaken the system as it approaches land
how does protection manage a natural hazard
the goal is to protect possessions, by modifying the built environment such as sea walls and earthquake-proof buildings.
Governments can try and change attitudes and behaviour to natural hazards which will reduce vulnerability.
name a case study that had management schemes that were a success
-mt etna= dynamite to divert the lava flow
-iceland (Eyjafjallajökull) pouring of sea water on lava flows
name a case study that had failed management schemes
Japan earthquake (1995) city of KOBE
-Japanese felt well prepared
-destroyed 100,000 buildings and 300,000 damaged
-6,000 death toll
-35,000 injuries
what is Disaster management cycle
PRE-disaster- risk management, mitigation/prevention, preparedness
response to the event- warnings/evacuation, saving people, providing immediate aid, assessing damage
POST-disaster- restoration, reconstruction(BBB), economic & social recovery, risk assessment/prevention
what is the disaster response curve AKA: park model
1st stage RELIEF (hours-several days)
-medical attention, rescue services and care are delivered
2nd stage REHABILITATION (days-weeks)
-try and return to normality by providing food, water and shelter for those most affected
3rd stage RECONSTRUCTION (weeks-years)
- infrastructure and property and crops are grown back
-use the experience of the event to try and learn for the next one
SOME COUNTRIES DONT REACH NORMALITY AGAIN (HAITI)
what is distribution of a hazard
refers the to the spatial coverage of the hazard.
-wider effect (tsunami and volcanic eruptions Iceland)
what is magnitude of a hazard
size and impact
PLATE TECTONIC THEORY: GEOLOGICAL EXPLANATION
-Jigsaw fit
-evidence of a carboniferous glaciation 290 million years ago, with deposits found in INDIA, SOUTH AMERICA, ANTARCTICA
-rock sequence in northern Scotland and eastern Canada
PLATE TECTONIC THEORY: biological evidence
-fossil brachiopods found in Indian limestone are comparable to similar fossils in Australia
-fossil remains of a reptile (Mesosaurus) found in both South America and southern Africa this reptile could go in seawater so couldn’t have crossed the Atlantic
-fossilised remains of a plant which existed when coal was being formed have been located only in INDIA & ANTATRICA
what is Sea-floor spreading
-large tectonic slabs of the lithosphere -split apart from each other
-occurs at a divergent plate boundary
-as plate tectonics slowly move apart —> heat from the mantles convection currents makes the current material rise —> often forming a mountain of an elevated area of seafloor
describe the process of convection currents
- under the earth, the crust transfers heat which rises through the surface and cools back down in a circular motion.
-the convection currents converge –> plates move towards each other —> plates converge and the plates move together AKA RIDGE PULL
what is gravitational sliding
sliding away of plates from a spreading ocean ridge takes place with plate movement driven because of the higher elevation of plates at ocean ridges.
what is ridge push
as fresh magma wells up at the mid-ocean ridges to form the NEW YOUNG, oceanic lithosphere, a higher elevation is formed at spreading ridges.
- new oceanic crust gradually cools and thickens with age and is pushed downhill as new magma emerges from the active zone of divergence
what is slab pull
-more significant gravitational force acting on plates —> the movement is driven by the cold, older, more dense rock —> sinking into the mantle at deep ocean trenches and pulling the rest of the plate slab with them as gravity causes the slide downwards.
DIFFERENCE between slab pull and ridge push
Slab Pull: The force exerted by the weight of the subducted slab on the plate it is attached to.
Ridge Push: The pressure exerted by the excess height of the mid-ocean ridge.
how are rift valleys formed
eg: in EAST AFRICA
- when plates move apart on continental areas
- areas of crust drop between parallel faults to form the valley. an area between 2 parallel rift valleys forms an upstanding block AKA:HORST
what is pyroclastic flow
contains a high-density mix of hot lava blocks, ash, and volcanic gas
more at a very high speed down the volcano
destroys nearly everything in its path
extreme fires ignite and melts snow and ice
what is acid rain and how does volcanoes affect climate change
volcanoes impact climate change by causing amounts of volcanic gas, and aerosol droplets of ash injected into the stratosphere.
gases like sulphur dioxide cause global cooling, and CO2 promotes global warming
acid rain- volcanoes emit gases which include sulphur, which combines with atmospheric moisture to form acid rain
what is volcanic gases
include CO2, carbon monoxide, hydrogen sulphide, and chlorine.
1986 CAMEROON (CRATER OF NYOS) killed 1,700 people due to CO2 emissions
what is a lahars
melted snow of ice as a result of the eruption combined with volcanic ash forms that can move down the course of a river at high speeds
EG: NEVADO DEL RUIZ (that girl)
28,700 population survived
what is a tephra
solid material of varying grain size ranging from volcanic bombs to ash, all ejected into the atmosphere
what are the primary effects of a volcano
tephra
pyroclastic flow
lava flow
volcanic gases
what are the secondary effects of a volcano
lahars
flooding
volcanic landslides
tsunamis
acid rain
climate change
how can you predict a volcano or is it possible?
NEVADO DEL RUIZ - volcanologists couldn’t predict as there was lots of activity within the volcano so couldn’t predict the big eruption.
-studying the previous history of the volcano is important to predict the timing.
-monitoring land swelling
-changes in groundwater levels
-changes in chemical composition in the groundwater and gas emissions.
how can a place protect themselves from a volcano
Mt etna - digging trenches
- dropping blocks into the lava stream
- using explosives to slow down the lava flow and in some cases divert it.
HAEIMAEY (ICELAND) - poured seawater at the front of the lava flow to solidify
HAWAIIAN island - build barriers across the valley to protect settlements
Eyiafjallajokull
-erupted 3 times in 2010 - 20th March/April-may/June
-persistent erupting lasting 39 days
what were the primary effects of Eyiafjallajokull
-ash blocking the sun which meant daytime = night (blackout)
-houses/roads/crops all destroyed
-stopped airspace —> Billions of pounds
—> cost airlines 130 million pounds a day
-Kenya was affected as 5000 workers were laid off from work as flowers and vegetables were rotting in the airport. Kenya’s flower council said they lost 1.3 million each day
what were the secondary effects of Eyiafjallajokull
-sporting events were cancelled due to flights being cancelled (champions league semi-finals feat: Barcelona and Lyon making long journeys by coach)
-fresh food imports stopped
-local freshwater sources CONTAMINATED with fluoride
-flooding —> caused by glaciers
Montserrat background
-300 years dormant
-In 1995 it began to give off warning signs
-largest eruption in 1997
Montserrat effects
1995- devastated the island with pyroclastic flows
—> The island was then evacuated to the north or the island, neighbouring islands, UK
-19 people died due to the eruption (as they wanted to come back to their homes and tend to their crops)
-Lahars (mudflows) destroyed the capital (Plymouth), covered in ash and mud
the airports, hospitals and roads DESTROYED
Montserrat RESPONSES ST
(short-term)
-evacuation
-identification of danger zones/abandoning of the PLYMOUTH
-British GOV gave money for the redevelopment ‘BBB’
-unemployment rose —> loss of tourism
Montserrat Responses LT
-exclusion zones set up in volcanic regions
-volcanic observation built to monitor the volcano
-new roads built and a new airport built
-services in the NORTH expanded
-the presence of active volcano —> TOURISM
where is the focus
the focus is in the crust and this where the pressure has built up
where is the epicentre
this is the point above the focus on earth’s surface.
what does the depth of the focus mean
shallow (0-70km): these tend to cause the greatest damage and account for 75% of all earthquake energy that is released
intermediate focus (70-300km)
deep focus (300-700km)
how is the Richter scale measured
1-10
an event measured at 7 is 10x greater than an event that is measure 6
MMS (moment magnitude scale)
1-10 on a scale
Based on the total moment release of the earthquake. The moment is a product of the distance a fault moved and the force required to move it.
what does the Mercalli scale measure
it measures the intensity of the event and the impact
goes from level 1-XIII (1-12)
WHAT ARE the primary effects of earthquakes
-ground shaking. The severity will depend on:
- magnitude
- its depth
- its distance from the epicentre
- local geological conditions
what are the secondary effects of an earthquake
-soil liquefaction
-landslides/avalanches
-fires
-effects on people in the surrounding area = collapsing buildings, destruction of roads systems and other forms of communication
what is soil liquefaction
when violently shaken, soils with a high water content lose their mechanical strength and start to behave like a fluid.
Japan, Tohoku
Background
11th March 2011
-9.0 on the Richter on the coast of Japan
-earthquake lasted 6 mins —> tsunami wave reached heights over 40 meters.
Japan, Tohoku STE
-15,894 death toll
- 6,152 injured
-330,000 buildings, roads, bridges and railways damaged
-blackouts with around 4.4 million people with no electricity
Japan, Tohoku
-cost $235 billion (most expensive natural disaster)
-earthquake moves the earth’s axis by 25cm shortening the day by 1.8 microseconds
North Bridge Background
- 1994 January 17th
-04:30
-6.7 magnitude
-southern California
-epicentre about 23 miles from Los angels
primary effects of North BRIDGE
-shock lasted about 10-20 sec
-killed 57
-would have killed more due to it being a federal holiday HOWEVER was at 04:30
-the deaths occurred in the buildings that were wood frame APs (famous in LA)
-low% of buildings destroyed
-transport was closed
-numerous bridges collapsed
-9000 injured
secondary effect of North bridge
-fires broke out/pipelines
-$13-50 billion in damages
-blocked/destroyed roads = no transport
-2 aftershocks 6.0 magnitude (the first one was 1 min after and the other was 11 hours)
North bridge STR
-aid was given out
-buildings listed ‘red tagged’ this is where they are a danger for residents = so many went to shelters
-the red cross put on clubs for boys/girls
Northbridge LTR
-many didn’t feel comfortable returning so stayed out of town for a while after the earthquake
-many got earthquake insurance on houses after the shock
predicting a seismic hazard
-very difficult.
-regions can be identified through plate tectonic theory
-monitoring of radon gas, groundwater levels and unusual animal behaviour.
-7 seconds app which warns on phone
prevention of an earthquake
-thought to be impossible
-schemes for lubricating the plates
protection from an earthquake
-FEMA (federal emergency management agency) put a programme together with these objectives:
-to promote understanding of earthquakes
-to better identify earthquake risks
-to improve earthquake-proof structures
-to encourage earthquake-proof planning and polices
Japan September 1st Disaster prevention day.
how can buildings be designed to help protect itself from earthquakes
-by putting a large concrete weight on top of the building which will move with the aid of a computer programme and will move in the opposite direction to counteract the stress
-putting large rubber shock absorbers in the foundations which allow movement of the building.
-by adding cross-bracing to the structure to hold it together better when it shakes.
Port au prince Haiti 2010 Earthquake (background)
January 12th 2010
-epicentre 10 miles away from the capital
-7.0 Richter scale
Vulnerability - lots of debt, poor housing conditions = exacerbates death toll
primary effect of Port au prince HAITI 2010
-flattened in less than 60 sec
-316,000 deaths
-parliament/police stations collapsed
-180,00 homes lost
-1.5 homeless
-600,000 left to live with host families
-5000 skl damaged
-liquefaction on looser sediment building subsiding
secondary effect of port au prince HAITI
-6.1 on Richter scale
-Government riddle with losses of civil servants
-City became lawless, escape prisoners with no police force
-cholera had killed 1500 people
-1.5 million still homeless
secondary effect of port au prince HAITI
-5.9//5.5 on Richter scale
-Government riddle with losses of civil servants
-City became lawless, escape prisoners with no police force
-cholera had killed 1500 people
-1.5 million still homeless
short term responses Haiti 2010
-countries gave aid (water purification)
-air/land/sea transport damaged air damaged due to the earthquake so AID WAS SLOW
-morgues overwhelmed with thousands of bodies
-delays led to angry appeals from aid workers and survivors.
long term recovery 2010 Haiti
$330 million EU gave/ world bank for 5 years
-Senegal offered land to Haitians
-6 months after 98% of rubble uncleared
-relief tents = 1.6 million
-$1.1 billion from charities and only 2% WAS RELEASED
-Dominicans allowed Haitian refugees
when a tsunami reaches land what factors will affect the tsunami
-the height of the waves and the distance they have travelled
-the length of the event (from the source)
-the extent to which warnings could be given
-coastal physical geography, both offshore and in the coastal area
-coastal land use and the population density
conditions that need to present for the formation of a tropical storm
-oceans must be at 27 degrees to provide a source of heat
-ocean depth of at least 70m
-location at least 5 degrees north/south of the equator in order for the maximum rotation of the air
-low level of convergence of air in the lower atmospheric circulation system
-rapid airflow of air in the upper atmospheric circulation - this pushes away the warm air which has risen close to the centre of the storm
how are tropical storms measured
Saffir- Simpson scale, hurricane’s maximum sustained wind speed. This scale does not take into account other potentially deadly hazards such as storm surges, rainfall flooding, and tornadoes.
tropical storms some info about
average of 7-14 days lifespan
80-100 storms develop around the world
factors that affect the impact on people of tropical storms
speed of movement (amount of time over an area)
-distance from the sea
-physical geography of the coastal area (width of the coastal plain or size of a delta, and location of mountain ranges
-the preparation of the community
-warnings and community response
major impacts that a tropical storm can produce
WINDS - can exceed 150 km/h (in scale 5 over 250 km/h) —> these winds can cause structural damage or even collapse them, bring down electricity transmissions and DEVASTATE agricultural areas.
-HEAVY RAIN - not unknown for rainfall to exceed 200 to 300 mm, this brings about flooding, landslides and mudslides.
-STORM SURGES - storm surges devastate low-lying coastal areas such as river deltas where the flooding can extend a long way inland. STORM SURGES CAUSE MOST OF THE DEATHS
furthermore, storm surges cause agricultural areas to suffer for a long time as soil is contaminated by seawater
prediction of a tropical storm
-it all depends on monitoring and warning systems such as National Hurricane Centre in Florida (USA) are able to access data from both land and sea-based recording centres.
-USA have aircraft such as the WC130J which is a plane that flies into a tropical storm to gather info about it. they can then predict the path of said tropical storm.
prediction —> evacuation of where the path could go
-if wrong with the evacuation people may become COMPLACENT
-it costs on average to evacuate a coastal area 1 million dollars per kilometre of coastal area to losses in business
- not always possible to give more than 12-18 hours of warning.
prevention of tropical storms
research into cloud seeding in order to cause precipitation. the theory is to release more water over the sea which will weaken the system as it approaches land.
protection against a tropical storm
-evacuation
-if evacuation does take place the national guard in the USA will get called to stop looting.
-people are educated on HOW to withstand a cyclone and the proper ways to strengthen their properties
-Cyclone drills in schools
-Land-use planning in areas vulnerable to storm surges.
-sea walls, breakwater and flood barriers can be built and houses on stilts
how can you prepare for a tropical storm
in Carolina, they put into place the Outer Bank mitigation plan.
aims are to save lives, money, property and natural resources which will reduce the vulnerability of the area in the future.
-> Those in richer parts are told to get insurance
Super Storm Sandy (background)
29th October 2012
-‘ Superstorm sandy’
-new jersey coastline
-passed through Jamaica, Haiti, Cuba, Bahamas
Risk and vulnerability
-> wasn’t used to getting hit by storms
-> Near to shoreline
primary effects of superstorm sandy
-winds up to 160 km/h
-widespread flooding
-286 killed
-346,000 houses damaged in new jersey
305,000 in NYC
Secondary effects of superstorm sandy
-storm surges
-power cut to over 600,000 people
-In Haiti 50 died, and 200,000 homeless
-70% of crops destroyed in Haiti
-$71 billion in damage
-run out of essential
STR of superstorm sandy
-President of the USA told people to stay calm
-evacuation
-schools closed down
-relocation of people
-emergency supplies of petrol were given
LTR of superstorm sandy
-re-building of homes
-raising money
-USA invested in more prevention, protection and planning
Typhoon Haiyan, Philippines
-started 2nd November 2013
-hit 4th November 2013
-storm surges, heavy rainfall and flooding occurred
Typhoon Haiyan, Philippines
-started 2nd November 2013
-hit 4th November 2013
-storm surges, heavy rainfall and flooding occurred
risk and vulnerability Hiayan
-Tacloban - the centre of the Philippines
-moved to the countryside for opportunities
high density is often overcrowded (LICs - large families to work)
-poor construction = vulnerable to storm surges
-houses on hillsides vulnerable to high rainfall or cyclones
-low lying areas wasted away
primary effects of Hiayan
-300 mm rainfall in 12 hours
-6000 died
-90% of Tacloban destroyed
-destroyed buildings, schools, churches
secondary effects of Hiayan
-huge storm surges (up to 6 meters) responsible for most of the deaths
-1000 missing bodies
-2 million homeless/6 million displaced
-20,000 fleeing the capital
-power stations destroyed
-flooding/landslides blocked major roads
-Tacloban airport blocked
-damages over $2.9 BILLION
STR Hiayan
-international government agencies gave aid
-water purification
-US aircraft looked for people and assisted in the search
-1200 evacuation centres set up —> provide help for families
-Field hospitals set up
-Catholic country —> CAFOD —> aid workers
-red cross gave basic food
LTR Haiyan
-‘BBB’ - roads/buildings/airports
-‘cash for work’- move debris
-fish and rice farming quickly resumed/re-established
-Aid agencies (eg: often gave fish boats)
-new homes built far from flooded areas (built without eaves so roofs didn’t fly away)
-cyclone shelter for those lost homes
natural fires little facts
wildfires sweep rapidly over the ground, consuming litter, grasses and herbs, and scorching trees
-possible to reach over 1000 Degrees
-crown fires are those which spread on the canopy of trees
retardants
chemicals sprayed onto fires in order to slow them down.
Pyrophytic vegetation
pyrophytes are plants adapted to withstand fire, methods of survival include thick bark, tissue with a nigh moisture content and underground storage structures
how fires are started
-LIGHTnING is the most common
-climate will affect how many electrical storms happen
-areas of low rainfall
-falling power lines
-throwing of discarded cigarettes (tymek)
-children playing with matches, campfires
-agricultural fires (controlled burning) which get out of hand.
fuel for forest fires
-sufficient quantity and dry enough fuel to burn.
-climate affects the frequency and duration of droughts during which the vegetation and litter have an opportunity to accumulate and dry out.
countries and places that suffer from wildfires
-parts of Australia
-USA and Canada (California and Florida)
-France/italy/Greece/cyprus
primary effects of wildfires
-loss of crops, timber and livestock
-loss of life
-loss of property
-release of toxic gases and particulates
-loss of wildlife
-damage to soil structure and nutrient content
secondary effects of wildfires
Evacuation
increased risk of floods
preparing, mitigating and preventing a wildfire
managing the vegetation - done by controlled burning to get rid of litter to create firebreaks in advance rather than during the event
managing the environment - this is done by increasing the gap between houses
modelling - studying the ways in which fires behave by using a computer simulator to predict the fire’s behaviour
education - in areas susceptible to wildfires
warning systems - there can be lockout towers or air patrols
community action - the authorities focused on those who live in vulnerable areas and suggest actions to take place so they can be self-sufficient
—> Local developed their own:
-warning techniques
-ensuring buffer zones were maintained
-conducting brush and street cleanups
-running equipment training sessions
Victoria case study (background)
-many fires occur in Victoria
-sparks from falling power cables
-sparks from power tools
-machinery
-arson-deliberately
Victoria case study (effects)
$4.4 billion
1.2 billion in insurance claims
-173 deaths - 1 firefighter
-3500 destroyed (2000 houses, 1500 farm buildings)
-7000 displaced people
-450,000 ha = HEACTER was burnt
-agricultural loss
-parks damaged
-RSPCA 1 animal perished
-60,000 lost electric supply
-looting occurred
FDI (fire danger index) (predict)
this is advised to leave an area during fire season
-temperature
-humidity
-wind speed
-dryness of vegetation
