Tectonic Landscapes And Hazards Flashcards
How many years ago was the earth formed ?
-4600 million years ago
-since then its been cooling to form 3 main layers
What are the three layers of the earth ?
-Inner core- centre, solid iron and nickel, 5500 degrees. Outer core- liquid iron and nickel
-Mantle- diameter of 2900km, made up of magma, convection currents in the mantle rise causing plate movement
-Crust- thin solid outer layer, between 0-75km thick, continental crust (land), oceanic crust (sea bed)
Are earthquakes and volcanoes found at plate margins ?
-earthquakes and volcanoes are not distributed evenly around world- tend to be clustered around earths plate boundaries
-zones of activity include the ‘pacific ring of fire’ and the mid Atlantic ridge
-some volcanoes can occur away from plate boundaries- at hotspots such as Hawaiian islands
- Earthquake examples- Haiti jan 2010 7.0, chile feb 2010 8.8
-Volcanic eruptions examples- Merapi Indonesia, Mt St Helens 1980
What is a volcano ?
-cone shaped mountain formed by material from the magma being forced through a vent in the earths crust
-Magma rises through weaknesses is the earths crust
-Pressure builds up inside the earth
-Pressure is released and magma explodes to the surface causing a volcanic eruption
-the lava cools to form a new crust
-after several eruptions the rock builds up and a volcano forms
What are the features of a volcano ?
-extinct- no magma chamber
-dormant- could erupt in future but hasn’t for over 10,000 years
-active- 1 eruption in past 10,000 years
-variety of shapes and sizes depending on the viscosity (stickiness) of the magma, the amount of gas in magma and the way in which it reaches the surface
-large scale- strato, shield and caldera
-small scale- lava tube, cinder cone, geyser
What is a cinder cone ?
-bowl shaped crater
-gassy basaltic lava blows into the air and breaks up into small fragments called cinders
-they cool quickly and fall onto slopes forming circular volcanic cone shapes
-Paricutin, Mexico
What is a lava tube ?
-lava channels flow and surface layer hardens
-once the eruption stops the lava tube will become empty and form a tunnel
-Iceland
What is a shield volcano ?
-found at constructive margins and hotspots
-runny basaltic lava flows over a large area forming a gentle sloping volcano
-eruptions are gentle and non destructive
-Mauna Loa, Hawaii
What is a strato volcano ?
-formed from ash and sticky magma
-thick lava travels slowly and builds up around vent forming a steep sided symmetrical cone
-violent eruptions with pyroclastic flow
-destructive margins usually
-Cotopaxi, Ecuador
What is a geyser ?
-vent in the earths surface that ejects a column of hot water and steam
-water underground is heated by geothermal heated rocks
-water is stored until enough pressure builds up
-Strokkur geyser in Iceland erupts about every 7 mins
What is a caldera (super volcano) ?
-a depression (dip) at the top of a volcano after a massive eruption
-magma chamber empties and crater collapses
-this can fill with water to form a lake
-eruptions are very destructive but hundreds of thousands of years apart
-Yellowstone, USA is 18km wide
What are some primary volcanic hazards ?
-lava flow- molten rock flowing down sides of volcano
-Lahars- mudflows, mixture of ash and water
-dust and ash clouds- ash thrown high into the atmosphere shuts out the sun
-lava bombs- large pieces of rock and ash are thrown into the air
-pyroclastic flow- burning clouds of gas and ash, temps up to 1000 degrees, rush down mountain scorching everything in its path
What are some secondary volcanic hazards ?
-indirectly caused by volcanic activity including lahars and landslides
What are the social issues caused by volcanos ?
-homes destroyed from ash and lava
-ash causes breathing difficulties
-death or injury
-water supplies contaminated
-transport disrupted
-long term- people have to be rehoused and people stranded if ash stops flights
What are the economic impacts caused by volcanos ?
-shops and businesses are destroyed
-transport and communication systems are interrupted so trade isn’t easy
-tourism may be lost due to fear
-farmland and crops ruined due to ash
-animals poisoned from drinking contaminated water
- long term- cost of rebuilding and insurance costs
What happens at a constructive/ divergent plate boundary ?
-plates move apart
- when plates move apart in oceanic areas this creates ocean ridge
-when plates move apart on continental crust they produce rift valleys
What’s an ocean ridge ?
-molten magma rises up to fill gap pushing two plates further apart which forms new ocean crust
-sometimes new rock builds up to form submarine volcano which can rise above sea levels
-as new crust forms and spreads transform faults occur at the plate boundary
-movement of the plates can lead to friction and form earthquakes which tend to be triggered near the surface and shallow focused
-an example of ocean ridges are mid Atlantic ridge- Atlantic Ocean is widening about 9cm a year
What’s a rift valley ?
-at constructive margins in continental areas the plates move apart, the crust widens and thins and areas dropped down between the faults to form rift valleys
-Streams and rivers may flow into the low valley and long lakes can be created
-Volcanoes begin to form around the area as the magma forces its way through the fractures in the Earth surface
-Eventually the widening crust along the boundary may become so thin that a piece of continent can break off to form a new tectonic plate
-can form strato volcanoes
-Iceland sits on the mid Atlantic ridge and has been torn into at the pingvellir National Park. This crack is 7.7 km long.
What happens at a destructive/convergent boundary?
-The plates move towards one another
-oceanic plate is forced beneath the continental plate creating a subduction zone or ocean trench
-The plate scrape together generating friction and this can set off earthquakes
-Due to the increased pressure and heating, the oceanic plate melts whilst being enforced into the mantle
-This newly formed magma is lighter than the surrounding mantle and it rises to the surface through vents to form strato volcanoes
-Destructive boundaries, con create fold mountain, strato volcanoes and ocean trenches
-An example is the nascar plate (oceanic) being forced under the South American plate (continental) creating violent earthquake such as Nevada del Ruiz
What happens at a collision/ convergent plate boundary ?
-two continental plates move towards one another
-two plates collide and the land buckles and pushes upwards, this can generate a shallow earthquake and creates fold mountains
-Indian and Eurasian plates are moving towards one another at a rate of 5cm a year creating the Himalayan mountains
What happens at a conservative plate boundary ?
-plates slide horizontally past one another
-horizontal movement creates transformation faults, plate boundaries often ‘stick’ which creates a build up of pressure, which may be released as friction as plates slip to its new position, seismic energy (earthquakes) are created
-transformation faults are created here
-an example is the 1300km long San Andreas fault where the pacific plate moves faster than North American plate
What are some key facts about earthquakes ?
-can occur at any plate boundary
-focus- source of the shock wave
-epicentre- earth surface immediately above
-shallow earthquakes cause more damage as the seismic wave has travelled less distance to the surface
-seismograph is used to measure the size of an earthquake on the Richter scale
-biggest earthquake recorded was in chile in 1960 measuring 9.6
What factors impact the effect of an earthquake ?
-strength of earthquake and distance from the epicentre
-nature of surface rock as some ‘shake’ more than others
-number of people who live in the area and time of day
-extent of preparation in an area and availability of emergency services
-primary hazard- ground shaking
- secondary hazard- tsunamis, landslides
Why do people live in hazardous zones ?
-500 million people live in active zones
-economic reasons-
-dramatic scenery created by volcanic eruptions attracts tourists which brings money into an area, Iceland
-lava and ash deposited during an eruption provides valuable nutrients for soil, making it very fertile and good for agriculture
-high level of heat and activity inside earth close to volcano provides geothermal energy
-social reasons-
-people born there and do not want to move as they feels advantages weigh out disadvantages, California- warm weather, tourism, wealthy area, jobs
-some people living in LICs cannot afford to move- Haiti
-prediction and earthquake resistant buildings are constantly improving, people feel educated and safe to live there- Tokyo and California
What makes an area vulnerable to hazards and how can it be reduced?
-threat to people created by earthquakes depend on a number of people- strength of magnitude
-number of people who may be affected
-vulnerability of people affected by the event- young, homeless, elderly and poor are more at risk
-to reduce vulnerability organisations need to
-reduce impact of hazard- monitoring, mapping, planning, predicting and preventing
-educating to cope with hazards- create a disaster plan, coordinate emergency services, educate citizens on what to do before, during and after
-tackle the root cause of vulnerability- government need to reduce poverty and inequality so everyone has same level of protection
What are some social effects of earthquakes ?
-homes destroyed
-people killed or injured
-water supplies contaminated- pipes burst
-gas pipes leaked causing fires
-transport disrupted as rubble on train tracks
-services (school, libraries) closed, destroyed or disrupted
-long term- people have to be rehoused and diseases like cholera may be spreading
What are some economic impacts of earthquakes ?
-shops and businesses destroyed- jobs lost
-transport and communications disrupted meaning trade isn’t easy
-tourism may be lost due to fear
-cost of rebuilding and insurance costs
-long term- cost of rebuilding, insurance claims and debt if country is poor
What are some factors affecting vulnerability ?
-population density- greater the density, more vulnerable a population as there more chance of death from buildings collapsing
-education- educated people are able to plan for survival, elderly and children protected by government, in LICs there is no planning and poor are vunervakle due to lack of education
-level of development- richer a country more moneys can’t be spent on hazard management like scientific predicting and building technology
-island nations- they may be cut out from countries and immediate help, could take days to reach country, if airports, ports or roads damaged could be hard to get to, in LICs no government emergency coordination but in HICs they’re more self sufficient and have plans in place for recovery
-multiple hazard locations- these places experience many natural hazards, country will be in dept from spending money recovering from other hazards, so no money for hazard management and educating locals
-closeness to plate margin- countries nearer to margins are more at risk of damage from earthquakes and volcanoes
-government stability- stable governments focus on the wellfare of their people, management, education and monitoring of hazards are good, emergency procedures are in place to reduce panic, trade injured and speed up recovery
How are tsunamis formed ?
-powerful ocean waves caused by earthquakes at destructive boundaries
-The release of energy displace the ocean bed and creates a column of water that is forced upwards
-Waves are created that travel long distances across oceans
-As they approach shallower water near the coast, the wave built up to great height
-On 26th of December 2004 an earthquake of the West Coast of Sumatra triggered a tsunami 30 m high killed over 200,000 people and left 2 million people homeless
Was Iceland vulnerable?
-no
-eruption in 2010
-It is a HIC with developed technology and the availability to monitor earthquake activity, gas emissions and changes in the temperature and shape of the land
-The government acted quickly to evacuate (800) and text message and news report inform people of the event preparing them for eruption
-Glacier melt was predicted on the pathway are created to enable floodwater to travel safety towards the sea
-Ash forecasting allowed the Icelanders to wear face masks to prevent breathing difficulties-despite it being an island nation as a HIC and part of the EU well in boat networks enabled the transportation of food goods into the country
-Insured that the year traveller in Icelandic farmers were insured against damage inconvenience
Was Haiti vulnerable ?
-yes
-its an LIC
-most buildings are self built on marginal land and aren’t EQ proof
-earthquake education is poor- no emergency procedures in place
-overcrowded capital
-EQ was a day time event where people were at work, school etc
-many people without food water and medical kits
-multiple hazard location- hurricanes, EQ etc
-country is in dept from spending money on other hazards
-no money for 3 ps
-island nation that is isolated after event as communications and transport down- slow help response
What are some facts about Haiti ?
-island in the Caribbean
-population of 9 million
-Life expectancy 60 years
-Literacy rate 48%
-3 million live in Port-au-Prince the capital
-Poorest country in the West hemisphere
-Most corrupt government in the world
-66% of the population live on less than £1 a day
-haiti lies on a conservative margin
-Movement of the North American and Caribbean plate and a buildup of pressure over many years cause the earthquake on the 12th of January 2010 which measures 7 on the Richter scale
-Epicentre was 25 km from the capital
-there were many after-shocks
What were some of the short-term social impacts of the Haiti earthquake?
-220,000 deaths
-1.3 million homeless
-Dead bodies with many buried in mass graves , which is a health hazard
-Hospitals collapsed
-Increase in crime
What was some of the long-term social impact of the Haiti earthquake?
-1100 makeshift accommodations were made for homeless
-Diseases due to poor sanitation by November 2010 they were outbreaks of cholera
What was some of the short-term economic impacts of the Haiti earthquake?
-commercial building collapse so jobs and trade couldn’t continue
-airport and ports were damage making it difficult access areas for relief effort and search and rescue
-Roads were blocked by debris
-Government building was also destroyed making it difficult to coordinate relief efforts
-Services like electricity water sanitation were badly disrupted or destroyed
-Houses destroyed and damage about 100,000 homes were destroyed and 200,000 were damaged in Porto prints and the surrounding area
What were some of the long-term economic impacts of the Haiti earthquake?
-19,000,000 m³ of rubble and debris created a huge job to clear up
-There were frequent power cuts for over a year and insurance claims were high
-Transport and communication was disrupted meaning trade and long-term reconstruction was difficult
-cost of rebuilding the damage was about $11.5 billion
-Tourist industry declined due to fear
-People losing jobs- 1 in 5 people lost their job
What was the aid and recovery like in the Haiti earthquake?
-Government was unprepared and had no emergency plans in place
-There was a worldwide appeal for help relying on both international aid and NGO for assistance in the form of food, water, medical supplies, search and rescue teams and shelter
-Search and rescue teams took three days to get to Haiti
-the UN sent 10,000 troops to maintain law and order
-United Nations pledge $10 billion and they also provided food for 2 million people and they rebuilt the port
-The world bank donated some money to rebuild roads, improve the airport and repair buildings
-years on companies like Oxfam and water aid have provided sanitation and water pumps for 1.7 million people
What are some facts about Iceland ?
-Eyjafjallajokull is a structural volcano in southern Iceland. It is 125 km south east of the capital with a 2.5 km wide Caldera
-between March 3 and fifth 2010 the warning sides of an eruption
-by the14th of April a new phase began which was much more dangerous. The volcanic magma broke through the crust beneath the glacier and dissolved gases in the magma. So steam generated from the melting ice which caused a large column of fine volcanic ash (tephra) to be thrust into the atmosphere and 30,000 tons of CO2 entered the air daily.
-The eruption partly melted the glacier which shut off major floods which travelled towards farming settlements
-Wind carried ash south east towards Europe so visibility in the south east of Iceland was poor
-iceland lies on the Atlantic Ridge are constructed plate margin separating the Eurasian plate from the North American plate
-These plates are moving apart at a rate of 1 cm to 5 cm per year
-As the plates diverge magma rises to the surface to form several active volcanoes located in a belt across Iceland
What were some of the short-term social impacts of the Iceland volcano?
-800 people had to be evacuated from the area
-20 farms destroyed from lava flow
-Homes and roads were damaged
-Services like electricity were disrupted
-Local water supplies were contaminated from the ash
-air contaminated with ash and fumes causing breathing difficulties within a 30 km radius
What were some of the long-term social impact of the Iceland eruption?
-Hundreds of thousands of people were stranded in other countries
What were some of the short-term economic impacts of the Icelandic eruption?
-Wind moved into the air over northern and Western Europe and stop flights from taking off
-Sheep were poison from drinking from ash contaminated streams
-Farmland on the Reykjanes Peninsula flooded because of the glacier melt
-Crops were damaged by heavy falls of ash
What are some long-term economic impact of the Icelandic eruption?
-Drop in Iceland tourist numbers affected the economy, local peoples jobs and income
-huge impact in schools and businesses as workers were stranded overseas
-Businesses lost £80 million
-100,000 flights were cancelled so about 10 million air passengers were affected
-over 50,000 farmers were temporary unemployed as their fresh food could not be imported to wealthy European and North American countries
-Local flood defences had to be constructed costing the government £2 million
What was the response and recovery like during the Icelandic eruption?
-before during and after the eruption the Icelandic government worked with the Icelandic meteorological office (IMO) to provide education and relief to those affected in the country
-before- 800 people were evacuated and text message warnings were sent to residents
-During- sections of river embankment that supported the main highway were deliberately broken to allow glacier floodwaters to pass through the sea. People were asked to stay indoors because of the ash in the air and gas masks were issued for workers and locals. the IMO weather radar and British Met office tracked the cloud warning other countries and telling them safe flight paths
-After- within weeks bulldozers rebuilt the river embankments and the main highway was reconstructed. Further research was carried out as a long-term response to find better ways of monitoring ash and improving forecast methods Within six months tourism in Iceland increased and over 700,000 visited the country by the end of 2010.
How can risks associated with volcanic and earthquake zones be reduced ?
-its not possible to prevent tectonic hazards but risks can be reduced using the 3ps
-Predicting
-Preparing
-Preventing
How can volcanoes be predicted ?
-Volcanologists can use a variety of techniques including:
-remote sensor imaging- satellites monitor volcanic temperature increases and gas emissions
-seismometers- these measure increase in volcanic activity as magma fills magma chamber
-gas emissions- indicate increased risk of eruption as sulphur and carbon dioxide content increases
-volcanoes like Mount Etna, Italy are monitored closely at all times as they have been active very recently
How can people prepare for volcanic eruptions ?
-hazard mapping- allows volcanologists to work out lava flows, hot rocks, gases etc. this allows them to make accurate predictions and inform locals
-an exclusion zone around volcano must be created
-authorities and services trained in how to respond
-emergency supplies of basic provisions must be gathered
-good communication system needed- text messages, news reports and education in school
Examples of how can we prevent volcanic eruptions and their effects?
-eruption cannot be stopped but flow can be controlled and buildings can be designed to withstand ash fall
-concrete blocks can be dropped in crater to reduce lava flow
-sea water sprays can cool lava flow and were used during the 1973 eruption in Heimaey, Italy
-explosives used on mount etna to create a ditch in order to divert slow flowing lava
Why are some countries more vulnerable than others ?
-closeness to plate margin- more risk of damage. UK in middle of Eurasian plate so no volcanoes or major earthquakes
-population density- greater number of people in an area, more risk of death and destruction. In Haiti, 3 million living in capital in makeshift housing, which fell on top of people causing death and injury
-island nations- more remote and cut off from help after an event
-government support
-emergency services
- building technology- countries like japan and USA have earthquake proof buildings. LICs don’t have the technology available. In port-au-prince 90% of buildings not EQ proof
What are some ways to predict earthquakes ?
-Laser beams- used to detect plate movement
-seismometers- used to pick up vibrations in earths crust which may indicate an earthquakes
-randon gas escapes from cracks before an earthquake
-animal behaviour is monitored in china as they believe they can detect chemical changes in the ground
How do people prepare for earthquakes ?
-emergency plans- people need to know what they should do in an earthquake. Training involves holding earthquake drills and education people via TV and radio
-emergency kits- people put together emergency kits and store them in homes nay include tinned food, blankets and first aid items
-earthquake drills- in USA the Red Cross leaflets and ‘drop, cover, hold’ is used. Governments coordinate evacuation and relief programmes
How can we prevent earthquakes ?
-cannot stop it from happening but we can reduce impacts by constructing EQ safe buildings, roads etc.
-buildings designed with shake plates to improve urban design and ensure they will withstand EQ up to at least 7.0 an the Richter scale
-EQ proof buildings constructed in major cities and are designed to absorb the energy of an EQ and withstand the movement of earth
-bridges are also designed to withstand EQ power
-houses are designed with gas cut off valves to reduce fires and explosions
-buildings spaced apart to reduce domino effect
-retro engineering allows older buildings to be supported by a cage as an outer shell- Kobe Port tower in Japan
