T 1.1-1.4 Flashcards
Hazard vs disaster differences
Hazard is an event that is a potential threat
Disaster is where losses are actually experienced
Hazard risk equation
Risk = (event x vulnerability)/ capacity to cope
What is the essence of capacity to cope?
- about governance
- empowerment of individuals
- drills/ faith in government
Garman - resilience in Japan
How can magnitude be measured?
- use Richter scales
- use p&s scales
- use moment magnitude scale (MMS) - measure of an earthquakes magnitude based on its seismic moment
- volcanic explosivity index (VEI) - a relative measure of explosiveness of volcanic eruptions
Different forms of vulnerability
Physical - where they live
Economic - lost jobs, incomes and assets
Social - disadvantaged groups
Knowledge - training and education
Environment - population growth into risky areas
At what point is a hazard event classed as a disaster?
Any one of: 2000 deaths 200000 homeless 5% gdp drop 1+ year of aid
What is urban resilience made up of?
- metabolic flows - production, supply and consumption chains
- governance networks - institutional structures and organisations
- social dynamics - demographics, human capital and inequity
- built environment
Stats of actual tohoku earthquake
- struck 80 miles from the coast
- epicentre 43 miles to east - 9 moment magnitude
- caused a 133ft tsunami that swept through miles of land
- 20 ft high wall of water
- 500mph
- overwhelmed best tsunami defences in the world
- 2.5 minutes of tectonic activity caused all of this
Impacts of tohoku earthquake
- 16000+ dead, 6000 injured, 2500 missing
- 3.5% gdp drop
- vast damage to infrastructure
- damage to oil refineries causing fires(port of Sendai)
- radioactive vapour leaked from Fukushima plant
- 4 of japans 11 nuclear plants shut down
What does the PAR model suggest about vulnerability?
- socio economic context of a hazard is extremely important as even a small hazard can result in a larger risk due to the numerous possible influences on vulnerabiiity
What does context consist of?
- unsafe conditions
- dynamic pressure
- root causes
Unsafe conditions in Kashmir
- poor building practises and code enforcement
- houses built on undesirable steep land
- lack of knowledge on correct seismic construction
- loss of traditional skills ( dhajji dewari)
- increase in modernised concrete construction
- access road blockages due to landslides
Dynamic pressures in Kashmir
- deforestation due to illegal felling and corrupt practises
- population growth over long period (increased resource demand
- cold climate
- high agricultural dependency
- Chinese built Karakoram Highway
root causes of Kashmir disaster
- relations with Indian government meant less aid
- Afghan war
- long term RUM - higher urban pop. Density
Main responses to Kashmir disaster
- army
- US 5.4bn
- Pakistani Britons said aid
- UN provide 2.4m blankets, 1.2m quilts and 170k plastic sheets and 200k tarpaulins to strengthen tents
- Dhajji Dewari - traditional strong house design
Main barriers to help in Kashmir
- unseasonal torrential rain/hail
- harsh Himalayan weather blocked access for 6+ months
- fresh landslides
- corruption, poor literacy and education
- during Ramadan school day, parents sleeping , children inside school
Impact of Kashmir earthquake
100k dead, 138 injured, 3.5m displaced
Pakistan corruption index
31/100 very corrupt
Use of Park’s model
- framework for looking at how quickly an area can recover from disasters and if they can build back their capacity to cope
- it is a curve
Stages of the park model
1 - modifying the cause I’d the event ( pre disaster)
2 - hazardous event (relief hours to days)
3 - search, rescue and care (relief hours to days)
4 - relief and rehabilitation period, modify the loss (rehabilitation days to weeks)
5. Recovery phase, permanent rebuild of physical and social infrastructure to prevent repeat (reconstruction weeks to years)
Christchurch earthquake facts and impacts
- South Island, 2nd city
- magnitude 7.1 2011, then 6.3 in 2010
- 185 killed (building collapses)
- significant liquefaction (infrastructure damage)
- £12Bil loss - 3rd most expensive in history
Define resilience
Ability to resist, cope, adapt and then recover from natural hazards
What affects resilience
- nature of the damage dealt
- quickness event (caught off guard?)
- gov relations with other countries
- amount of economic damage
- new technology
What is the theory of plate tectonics?
Proposed by Alfred Wegener
- contingents have drifted into their new positions from one continent called Pangea into the ones we have in our present time through continental drift
What is Paleomagnetism?
Study of past changes in Earth’s magnetic field, which reversed roughly every 200k years
- magnetic minerals in cooling laça record this info, which has shown a symmetrical pattern either side of mid ocean ridges
Ridge push and slab pull
- driving force of plate tectonics
- mid ocean ridges are pushed away under gravity as they have higher elevation (ridge push)
- and under are also being pulled away by gravity fed by convection currents (slab pull)
- causes sea floor spreading
What is peridotite?
- a dense, coarse grained plutonic rock containing a large amount of olivine, believed to be the main constituent of the Earth’s Mantle
What is the Earths internal structure composed of?
- earths outer liquid core flows and swirls to generate our magnetic field
- most heat is generated within the mantle through radioactive decay, primarily composed to peridotite
What is the subduction zone?
- a location where one plate is being pulled down into the mantle, melted and recycled
What is a trench?
A deep area in ocean floor between two plates wherever subduction is occurring
What is convection?
Convection is the circulation of material caused by differences in density
- acts like a conveyor belt, moving lithosphere above it
- got mantle material rises up and comes into lower terms, lower pressure zones near crust, where it cools and goes back down to form a convection currents
How is new earth constructed?
Part 1v- earths structure
- is made up of inner and outer cores, mantle, outer crust, because of gravity acting on materials of diff. density
- core has metal, generates an unstable magnetic field that switches every 200k years
How is new earth constructed?
Part 2 - Earth cools
- 90% of heat at depth comes from radioactive decay in mantle
- temperature at any given depth is called geothermal
- as you go deeper, pressure and temp increase
- in asthenosphere, mantle is close to melt and behaves like a soft toffee
How is new earth constructed?
Part 3 - decompression melting
- pressure is lower as you get further away from the core and get closer to the crust
- because pressure is lower, as it rises it begins to partially melt
- melt forms in chambers and is called magma
How is new earth constructed?
Part 4 - mid ocean ridge
- magma collects in chambers and rises up to surface in waves because it is less dense than solid mantle
- it escapes from any developing fractures and errors at divergent plate boundaries, forming a ridge, if this ridge in mid of ocean it’s a mid-ocean ridge
- if above ocean - island (Surtsey)
How is new earth constructed?
Part 5 - sea floor spreading
- mid ocean ridge gets so heavy that, under gravity it begins to slide away in opposite directions
- slab pull also pulling plates in opposite directions
- two processes result in sea floor spreading at divergent plate boundaries
How is new earth constructed?
Part 6 - paleomagnetism
- new oceanic crust is being formed at mid ocean ridge and separating
- lava on surface has magnetic materials such as magnetite
- when the lava cools, mineral align in the direction of Earth’s magnetic field
- over time rocks have symmetrical pattern of polarity as they move further away from mid ocean crust and allow the next wave of new crust to form
1.1 overall
Working out how we calculate how big a risk a hazard is (Hazard Risk Equation)
1.2 overall
Risk of a hazards link to winder context - pressure release model
What are root causes
Are the overarching political power / economics which are the result of how power is distributed in society / determines how much the government is able to support / recognises the needs of different / marginalised groups of people in society
Dynamic pressures meaning
create unsafe conditions in particular areas / particular times because there are more people / less training / less press freedom / rapid city growth / deforestation etc
Unsafe conditions meaning
are specific ways that people are vulnerable because of where buildings are built / unsafe hill slopes / informal settlements / lack of health and safety / poor education / poor infrastructure
1.3 overall
How communities, societies and environments go about recovering
1.4 overall
Formation of crust at diverging plate boundaries like Surtsey (a mid Atlantic ridge in Iceland)
Partial melting at constructive margins
• Partial melting occurs where the warm mantle moves upwards into zones of lower pressures near the crust.
• This movements ensures Peridotite passes its threshold melting temperature.
• Minerals within Peridotite melt at different rates and slowly seep out to form magma chambers under constructive margins
Divergent/ constructive plate boundary definition + landforms associated
plates moving apart from one another, so magma rises between and forms new crust.
Landforms associated;
- Ocean ridges - surtsey
- Rift valleys - East African rift valley
- Shield volcanoes
Conservative plate boundary definition + landforms associated
plates slide past each other in opposite directions, or in the same direction but at different speeds, friction occurs and plates become stuck at faults, while pressure builds up, when this is released there is huge energy release - causing earthquake.
Landforms associated:
- Fault line - San Andreas fault
Destructive/ convergent plate boundary definition + landforms associated:
plates are moving towards each other, usually involves oceanic and continental plate, younger, denser oceanic crust forced beneath continental plate, forming an ocean trench. If two continental plates collide - neither can sink, and lank buckles upwards to form fold mountains. For two oceanic plates colliding, the denser one will go under.
Landforms associated:
- Stratovolcanoes
- Caldera volcanoes
- Ocean trench
- Fold mountains
In general terms what’s slab pull and ridge push
slab pull is when the converging plate gets subducted, so on the other end of the plate boundary, so it pulls the diverging side away. Ridge push is to do with the convection currents acting like a conveyor belt and the action of gravity.
What’s a hotspot
intraboundary tectonic landforms - where there are fixed spots in the mantle where magma rises to the surface, as the crust is moved over these fixed spots, volcanoes are created - eventually forming a chain of volcanoes.
