Natural Hazards Flashcards
what is an avalanche
an avalanche is a slide of large snow or rock mass down a mountainside, caused when a build up of snow is released down slope
what is a landslide
a landslide is related with an avalanche but instead of snow it occurs with actual elements of the ground including rocks, houses, trees. they can be caused by earthquakes, volcanic eruptions or instability of surrounding land
what is a mudflow
mudslides or mudflows are a special case of landslides in which heavy rainfall causes loose soil on steep terrain to collapse and slide downwards
what is a flood
floods are the result of prolonged rainfall from a storm including thunderstorms, rapid melting of large amounts of snow etc and cause widespread damage from flooding etc
what is a wildfire
an uncontrolled fire burning in wild land areas. commonly caused by lightning and drought however can be started by human negligence or arson
what is a cyclonic storm
hurricane, cyclone and typhoon are different names for the same phenomenon of a cyclonic storm forms over oceans. it ios caused by evaporated water that comes off to the ocean and becomes a storm
what is a tornado
a tornado is a natural disaster resulting from a thunderstorm. tornadoes are violent rotating columns of air which can blow at speeds between 50 to 300 mph
what is a tsunami
a wave of water caused by the displacement of a body of water. tsunami can be caused by undersea earthquakes
what is a volcanic eruption
a volcanic eruption is the point in which a volcano is active and releases its power. they mainly occur along tectonic plates
different responses to hazards
what is fatalism
people with fatalism view are often used to experiencing these hazards and may have lived through events many times. they see that the cons of living with a hazard are smaller than the benefits which can be offered
what is adaption/adjustment
the adaption approach is when a town or city starts to change their way of living to fit natural disasters into their everyday lives
what is prediction
knowing when a hazard will occur is hugely advantageous and can lead to significantly reducing death tolls and overall impacts. prediction can occur through different ways such as seismic monitoring, measuring has emissions and geological ground changes
what is mitigation
any action taken to reduce or eliminate threat to property or human life as a result of a natural hazard. this can include the idea of adaptation but can also include anything done on an individual level to reduce the impact of a hazard upon an individual. any mitigation carried out ned to go through a cost benefit analysis to ensure that its economically viable
what is risk sharing
when a natural hazard event occurs somebody always looses out. risk sharing works on the principal that spreading the risk reduces anyone, group or individuals risk therefore making it more acceptable while also may involve sharing the financial burden
what is management
the degree of management carried out heavily depends on the wealth of a nation
what is the park model
the park model if hazard response considers how the standard of living and economic status of an affected area changes following an event
what is the standard of living phase
how much you have and can buy economically
what is the relief phase
the immediate response, focus is on saving lives and property, charity teams such as the red cross, from outside the immediate area help with search and rescue and care operations, urgent medical supplies, rescue equipment and food may be brought in
what is the rehabilitation phase
more complex than relief, this may last for several months where efforts are made to restore physical and community structures or at least temporarily
reconstruction, mitigation and preparedness phase
permanent changes are introduced to restore the quality of life and economic stability to the pre disaster level or better this can also include mitigation and preparedness reducing vulnerability
hazard management cycle phases
-hazard event
-response
-recovery
-preventation/mitigation
-preparation
hazard event phase
-hazard severity probability
-vulnerability: root causes, social forces, unsafe conditions
response phase
-rescue and evacuation
-relief and external support
preventation/mitigation
-ongoing processes to lesson the severity of hazard on people/property
-rebuild buildings and houses
-introduce prediction methods
preparation phase
-actions prior to event to activate necessary resources
-shelter to go to stay safe
-leave the area that could get highly impacted
what are the different structures of the earth
-inner core
-puter core
-mantle
-crust
-asthenosphere
-lithosphere
what is the lithosphere
the slid top layer os the crust in which plates are formed, consisting of crust and upper mantle
what is the athenosphere
soft plastic like rock in the upper mantle just below the lithosphere
earths energy
-earths energy is left over from when it formed by arising from a cloud of gas and dust in space
-earth cools very slowly, to keep a steady temperature because it makes heat in its interior
-earths producing as much heat as its loosing through the process of radioactive decay which involves the disintegration of natural radioactive elements inside earth and when it decays it produces heat
-many rocks in earths crust and interior undergo this process of radioactive decay
-the rest of travel of waves from earthquakes are called ‘seismic waves’ which tells scientists about what material make up the planet
convection currents in the mantle process
- heat source - radioactive decay in the heat source
- rising limb of convection current. heated rock in mantle rises as it is less dense
- direction of plate movement due to movement of convection current below
- semi molten rock spreads out carrying the above plate with it
- cools and sinks back down to be reheated
plate boundary types
-constructive
-destructive
-collision
-conservative
constructive plate boundary
- at a constructive plate margin two plates are moving apart leaving a gap in the middle for magma to rise up through
-volcanoes form but dont erupt with force as the magma can escape easily
-earthquakes can also occur such as the mid atlantic ridge
-rift valleys can also form as land falls down into the space left as plates move apart
-mid ocean ridges and rift valleys can form at this plate boundary
destructive plate boundary
-at a destructive plate boundary dense oceanic plate descends below less dense continental plate
-as the plate descends it is melted due to friction with the continental plate, farming hot liquid magma
-this magma can then rise through cracks in the continental plate and form volcanoes if it reaches the surface
-earthquakes, volcanoes, fold mountains, ocean trenches can all form at this boundary
collision plate boundary
-collision plate boundaries occur when two plates of similar densities move together which causes material between them to buckle and rise up forming fold mountains
-the Himalayas are an example of this
conservative plate boundary
-conservative plate boundaries exist where two plstes do not directly collide but slide past each other along a fault
-no volcanoes are found along these boundaries but earthquakes occur
-such as the san andreas fault in california
-powerful earthquakes occur at this plate boundary
what are the three types of destructive boundaries
- oceanic- continental
-oceanic - oceanic - continental - continental
oceanic - continental plate boundary
-the oceanic crust which is thinner snd more dense than the continental crust sinks below the continental crust into the upper mantle
-this process is known as subduction
-destructive margins are some of the most seismically active zones in the world with shallow to deep focus earthquakes
-deep ocean trenches are found along the sea ward edge of the destructive margins
oceanic - continental ocean trenches
- as the dense oceanic nazca plate is sub ducted beneath the continental south american plate a deep ocean trench
-the trench extends 8km down in places is 64km wide
oceanic - continental fold mountains
-pressure put onto the continental crust can cause it to buckle upwards and from fold mountains
-in addition material on the ascending oceanic plate is scraped off and folded to form the mountain
oceanic - continental volcanoes
-benioff zone the further the rock descends the hooter the surroundings become. this together with the heat generated from friction begins to melt the oceanic plate into the magma
-as it is less dense than the surrounding asthensphere the molten material begins to rise in the great plumes up through fissures/faults in the buckled continental plate and by burning their way through overlying rock, eventually these reach the surface to for explosive volcanoes
-the andesitic lava has a viscous nature this creates complex composite volcanic islands known as an island can appear
oceanic - oceanic plate boundaries
-two oceanic plates moving towards each other
-one if forced under the other and the process involved with subduction being
-the crust that is subducted may be marginally the denser of the two plates is the one which is moving more quickly
-subduction occurs in the same way as at oceanic- continental but it is less clear which plate descends
tenches and arc at oceanic- oceanic
-earthquakes are frequent: subduction process produces shallow deep focus earthquakes some of which can be very powerful and sub sea earthquakes may result in the formation of tsunamis
-ocean trenches and island arcs are the main features as the interception tales place offshore
continental - continental collision boundary
-sediments scraped off vanishing ocean floors between the plates or volcanoes associated with earlier subducted are compressed to form young fold mountain chains with deep roots in the litosphere
what is the movement of plates at a constructive boundary
two plates are moving apart leaving a gap in the middle for magma to rise up through
what are tectonic features at a constructive boundary
-volcanoes form but dont erupt with force as magma escapes easily
-rift valleys can form ad land falls down into the space left as plates move apart
what tectonic features form at destructive oceanic- oceanic
trenches and arcs
what tectonic features form at destructive oceanic - continental
-trenches
-fold mountains
-volcanoes
what tectonic features form at destructive continental - continental
fold mountains
what is the movement of plates at conservative boundary
here two plates do not directly collide but slide past each other along a fault
what are tectonic features at a conservative boundary
-fault lines
-earthquakes do occour
how long did wagner think the plate movement has taken since pangea formed
300 million years
what was found when the mid oceans were mapped
both sides of the ridge were moving apart with a symmetrical image of both sides at the ridges
what did wagener initially struggle to explain
pull and push to how it was happening
as well as climate and landscape what else proved this theory
fossils
VOLCANOES
shield volcanoes
-gentle sloped and a wide base
-frequent eruptions of basic lava
-lava flows at high speeds and for long distances before cooling
-usually non violent eruptions
-non viscous lava due to basaltic composition
-found at constructive boundaries
composite volcanoes
-steep sided with a distinctive cone shape
-high with a narrow base
-explosive eruptions of lava and ash
-viscous lava builds in layers and does not flow far from the crater
-found at destructive boundaries
-secondary or parasitic cones formed when the main vent gets blocked
icelandic eruption
low viscosity and highly effusive and may have water therefore phreatic
hawaiian
effusive, miner explosivity with fire fountain snd low viscosity lava flow
strombolian
eruption with has bubbles so eject tephra
vulcanian
higher gas build up than strombolian higher visous kava a series of short lived eruptions with tephra including bombs
plinian
highly explosive large eruption columns range of tephra and plyroclsstic fallout icluding flows
measuring eruptions
-VEI scale (volcano explosivity index)
-it is similar to the richter scale and mercalli scale which measures the intensity of earthquakes
-the VEI measures explosivity voume of ash and the height ash reaches into the atmosphere
-it gives a description of the eruption a name fdor the eruption and the total number of those eruptions in human history
-it allows for comparison between events being made
-it is measures on a scale from 1-8
what are lahars
- a mixture of hot or cold water snd rock fragments which flows down the steep side of a volcano
-lahars form when erupted volcanic material gets saturated during periods of heavy rain
what is lava flow
- a flow of magma down the surface of a volcano
-there are two different types: Aa flow and Pahoehoe flow
-Aa flow: is a few metres thick with a mix of uneven shaped sharp edges ash and cinder blocks and flows a distance of 0.5 - 10 km
-Pahoehoe flow: is fluid rather than viscous but does not move quickly, often the surface layer is static whilst flow continues beneath it and flows a distance of 1-90km
what is volcanic gases
-gases can be emitted from before after or during an eruption
-they can be: carbon dioxide, hydrogen chloride, hydrogen fluoride, hydrogen sulphide, sulphur dioxide
what is tephra
-the general term given to anything thrown into the air during a volcanic eruption and it can range from individual ash particles all the same way to volcanic bombs
what is nuess ardentes/ pyroclastic flow
-a chaotic mixture of rock fragments, gas and ash that travels rapidly away from a volcanic event
-a common cause is when the column if lava, ash and ghases expel from a volcano and loses it upward momentum and falls back to the ground
the methods of managing volcanic risk
-prediction
-protection
-preperstion
monitoring (prediction)
-geological observations: several different techniques exist with for measuring the topography of a region the ground movement that occurs around a volcano when iots active. slope angles a tiltmeter is used to measure changes in the slope of a volcano side. distance measurements are used to measure horizontal change
protection/preperation
-this is a method which can maintain the people affected ones wellbeing as little can be done to protect their home during an eruption
-evacuation plans to stay away from threats such as lava, mud flows or flying rocks or debris
-lava control idea
-cool it with water plan
implementing
build a barrier:
-barriers of rock and ash were constructed in attempt to divert the lava to prevent damage to areas to be casued
EYJAFJALLAJOKULL
basic info
-occouring in april 2010 towards the end of the easter school holidays the eruption of eyjafjallajokull impacted most of europe in some way
- eyjafallajokull is located in the middle of the south of iceland between skogafoss and mydralsjpokull in the eyjafjoll mountains
short term responses
-the area around the volcano was evacuated
-european red cross mobilised volunteers, staff and other resources to help people affected directly or by the eruption of ther eujafhallajopkull glacier volcano
-european red cross provided food for the farming population living in the vicinity of the glacier
-700 people were evacuated from the disaster zone three times in the past month
-in one instance people had to flee their homes in the middle of the night to escape from flash floods
long term responses
-eu developed intergrated structure for air management as 9 functional airspace black will replace the exisiting 27 areas
-structures re built
-sent researcher to monitor volcanoes
who was involved
-red cross/associating organisations
-air traffic control
-Icelandic goverement
to mitigate the damage they have
-monitored volcano
-set up evacuation zone
-reinforced buildings
-land zoning (restrict the physical development and us of specific parcels of land)
what is seismicity
is earth shaking and can be human induced e.g via reservoir construction, fracking or mining
how does a seismic event occour
1)pressure builds at the point where 2 plates meet
2) sudden release of pressure due to rock failure creates waves
3) the waves cause the ground to shake
4) the intensity of the shaking is dictated by the depth of the focus and the energy release
5)the result of this is the earthquake hazard §
what are the different types of seismic waves
-p wave
-s wave
-rayleigh wave
-love wave
what is a p wave ( primary wave)
-moving across the surface similar to a pulse creating a series of compression and extension
-less damaging
-these create lateral movement meaning no horizontal or vertical change
-only one direction
what is a s wave (secondary wave)
-only travels in one direction
-ripple of rising and falling motion in a vertical plane
-making the ground go up and down
-travels more slowly
-more damaging
what is a rayleigh wave
-movement of up and down
-slow moving waves
-have a rise and fall
-extensions are created in the vertical plane
-can rise the ground apart
-steady rise and fall
what is a love wave
-pulsing motion sideways
-shakes the ground side to side
-extremely damaging especially to structures
what causes a tsunami
- a tsunami is a large ocean wave that i caused by sudden motion on the ocean floor
-sudden motion could be an earthquake, a powerful volcanic eruption or an underwater landslide
-the impact of a large meteorite could also cause a tsunami
what are the characteristics which make areas susceptible to liquefaction
occurs in areas that have groundwater near the surface and sandy soil
what is liquifaction
-liquefaction is the mixing of sand or soil and groundwater during the shaking of moderate or strong earthquake
-when the water and soil is mixed, the ground becomes very soft and acts similar to quicksand
-if liquefaction occurs under a building it may start to lean, tip or sink several feet
-the ground firms up again after the earthquake has past and the water has settled back down to its usual place deeper in the ground
what are landslides
-ground shaking due to earthquakes destabilises cliffs and steep slopes, causing landslides and rock falls as a significant side effect
-landslides are especially common in highland areas many of which are fold mountains meaning they sit on unstable plate boundaries
what methods are used to predict earthquakes
-past seismic events
-remote sensing
-radon gas emissions
past seismic events
-looking at past events help to predict when one is going to occur in the future which can give a rough timescale of when one is going to occur
-this method is not reliable but can say where a event is likely to happen
remote sensing
-the process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance (typically from satellite)
-place 2 GPS on either side of the plate boundaries and they presume pressure is building therefore leading to prediction of an earthquake
radon gas emissions
-increased levels of radon gas have been observed in association with rock cracking that causes earthquakes
-radon gas is found in rock, if excess radon is detected it signifies rocks cracking which can be a indicator for seismic earthquakes
-trapped in cracks in cavitys and when cracked the level of the gas will increase meaning more is released
-can give false readings and can be unreliable
measuring earthquakes
- we use a seismonitors to measure an earthquake
-these machines are used to plot a seismograph which we can then determine just how much shaking occurs
-the richter scale and the modified mercalli intensity scale are two main methods of monitoring earthquake strength following an event but in two different ways
mercalli scale
- the intensity scale consists of a series of key responses such as people awakening, movement of furniture, damage to chimneys and total destruction
-the loer numbers of the intensity scale generally deal with the manner in which the earthquake is felt by people
-the higher numbers of the scale are based on observed structural damage
richter scale
-measures all the ground deformation and energy release by an earthquake
-this is a logarithmic scale
tropical storm formation
-strong upward movement of air draws water vapour up from the warm ocean surface
-the evaporated air cools as it rises and condenses to form towering thunderstorms and clouds
-condensing air releases energy which powers the storm and draws up more water
-several small thunderstorms combine to form a giant spinning storm surface winds exceed 120km/h and a tropical storm is officially born
- storm develops an eye where air rapidly descends most intense winds are found in the eyewall on the edge of the eye
-storm is carried across the warm ocean it continually gathers strength and energy
FILL IN THE FINAL STEP
what are the hazards which can occur from a tropical storm
-storm surge
-strong winds
-landslides
-rover flooding/heavy rainfall
storm surge
-a storm surge is a change in sea level which can lead to mass flooding
-the low pressure at the centre of the storm pulls the water up as there is low pressure on the ocean surface
-another factor affecting storm surges are strong winds pushing the sea water towards the coast
strong winds
-atmospheric pressure: rising and sinking of air in the atmosphere and sea surface temperature
-risk of high winds means debris are carried by high winds which can cause extensive damager to properties and infrastructure
-factors which can affect high winds are high sea temp, air density, landscape
landslides
- a landslide is the movement of mass of rock, debris or earth down a slope
-landslides occur when the downward force of gravity acting on a slope is greater than the force holding the soil particles together
river flooding/heavy rainfall
-the process when water spills over the banks
-this can be caused by excessive rainfall or the melting of snow
-also deforestation can cause river flooding due to the water not being intercepted by the trees
-rapidly rising warm air spirals upwards and cools, condenses and cumulation clouds form
HURRICANE SANDY
timeline
-October 22nd low pressure system developed sufficient organised convection to be classified as tropical depression
-it moved slowly at first due to a ridge to the north, low wind sheer and warm waters which were for hotter allowing it to strengthen
-october 24th - an eye began developing and it was moving steadily northward
-the national hurricane centre upgraded sandy to hurricane status about 65 miles south of kingston jamaica
-october 23rd 2012- the part of hurricane snady was correctly predicted by european centre
-the computer noted that the storm would turn left west towards land and strike the new york/new jersey areas on october 29th
-rather than it turn east and head out to the open atlantic as most hurricanes, this was because of cold air to the north snd jet stream to the west, which combined to pushing the storm over warmer coastal water
social impacts of hurricane sandy
-affected 24 states
-63 billion dollars of damage
-111 deaths - 41 of which were in new york
-1600km length of the continent was affected
-south carolina suffered for 50 hours
-storm surges rose 6-7 m in new jersey
-many roads were impassible
-1 million had to evacuate homes
economic impacts of hurrican sandy
-new york stock exchange was closed for three days
-tens of million of dollars in revenue were lost from closing of the stock exchange
-business reports from companies and countires around the world were delayed due to lack of power
-banks closed across the north eastern states and people had restricted access to their hands
-8,1 million businesses were left powerless
-3 closed airports
political impacts of hurricane sandy
-sandy interrupted presidential election campaign
-there was heavy political criticism in responses
environmental impacts of hurricane sandy
-the worst rainfall in a century
-flooding, trees and car crashes caused by the storm
-23 fires across the city
-70-80% crops destroyed due to fired
-development of economic party caused increased in global temperatures
-1.5 m of flooding in new jersey
short term responses
-police evacuated hundreds of thousands of people from low lying areas
-people temporarily relocated to evacuation centres such as schools and community centres
long term responses
-government developed plans to prepare for tropical storms
-investments made in flood prevention and coastal protection
-local people and emergency services teams will need training in how to responds to tropical events to hopefully reduce the impact on people and the environment
TYPHOON HAIYAN
causes and background
-November 7th and 8th 2013 - occurred int he late afternoon and night with high winds and devastating storm surges
-tropical depression was first tracked on november 2nd and continued to grow and feed off the tropical ocean temperatures which then caused it to develop into a fully fledged tropcial storm ever recorded making landfall on november 7th making a further 5 landfalls as it crossed the country
social impacts
-killed 7500 people and effected 9 million
-phillipines faced humanisation crisis days
-1,9 million left homeless
-6 million displaced
economic impacts
-impacts estimated at 2.9 billion dollars
-major rice and sugar productivity destroyed
-between 50000 tons and 120 000 tones of sugar may have been lost
-71000 hectares of farmland damaged and 85 million lost due to farmer damage
environmental impacts
-loss of forests, trees and widespread flooding
-oil and sewage leaks into the local ecosystems
political impacts
-formally declared ‘a state pf national calamity’ and asked for international help
organisation responses
world vision
-educating the community on how to recover themselves
-looking over and building housed that will be more sustaining in similar conditions that will be more protective
-the idea of build back better allowing them to be better prepared eventually will reduced the need for international aid
save the children
-provided more venerable families with support
-fed families restoring their livelihood
-introduced new designs of homes
-introudced WASH
what is required for a wildfire to occur
-fuel
-heat
-oxygen
AUSTRAILIA WILDFIRES 2019/2020
location
-north austrailia where 42 million acres burnt
-3000 homes destroyed
-5000 animals displaced
-started in queensland and spread down the coast
what were the causes of the austrailian wildfires
-climate change: hottest and dryest period ever known recorded
-dry lightning trikes
-austrailia is one of the worlds largest coal exports
what were the effects from the wildfires
-33 poeple perished
-100 billion austrailian dollars in damage and economic losses
-turned forests into empty land
-38,000 insurance claims
-2-3 billion dollars damage
what were the responses to the wildfires
-peoples reaction such as portests and objection to the use of fossil fuels
-fuel management getting ride of potential fuels
-enhancing early detection systems
-new technology developments to minimise injuries of firefighters
-using satellites to fight bush fires more intelligently and safely
MULTI HAZARDOUS CASE STUDY
Phillipines subject to many hazards due to its location and known as the pacific ring of fire
-there are 22 active volcanoes
-highly susceptible to earthquakes
LOCAL SCALE : CARACAS
caracas
-the capital city of venzuela
-located in the north of south america bordering columbia, brazil and guyana
-the wealth is very unevenly spread and poverty and crime is rife
causes
-1999 tropical storms lead to heavy rainfall causing the triggering of mudflows and landslides killing over 10,000 people
-situated on the south american plate with fault lines running through the city and main airport
-large major earthquake in 1967 with a magnitude of 6.5 killing over 300 people
-caracs is primarily situated in the base of a large valley making it very susceptible to landslides triggered by tropical storms and tectonic activity
-
social factors
-clear division in city (rich on valley floor where the most valuable land is found/ poor on valley sides)
-landslides impact poorer residents more as they live on valley sides
-buildings on valley floor are widely spaced to enable evacuation
-lack of equality and education
economic factors
-service focused economy: organisation have their own response pland not city wide
-lots of unemployment and no insurance
-50% of GDP from oil
political factors
-does not have a stable goverment open to corruption
-often disagrees with HIC
-blockaded from US because of political disagreement
NEPAL EARTHQUAKE 2015
causes and key background
-7.8 magnitude
-destructive plate boundaries
-release of pressure at the indian/eurasian destructive plate boundary where both plates are continental
social effects
-8000 died
-18 died on everest
-600000 homes destroyed
-2.6 million left homeless
-71000 schools destroyed
-14500 injured
economic effects
-6.6 million cost of rebuilding
-set country back 100 years
-tourism reduced by 72% the following year
-GDP went down by 9-50%
political effects
-government critics for not having strict building regulations meaning they were easily damaged by earthquakes
short term responses
-people dug with bare hands to retrieve poeple and bodies
-funeral pires in street
-rescue teams from USA, UK
-3 helicopters deployed for search and resue
-300000 evacuated from katmandu
-oxfam installed 11000 litre water tanks
-7000 schools re built
long term responses
-asian developing bank gave 200 million to help rebuid
-new building codes enforced
-medical teams educated people to be prepared for future earthquakes
