Paper 1: Tectonic Hazards Flashcards
crust
surface of rock
-made from cooler, solid rock
-split into plates
lithosphere
rigid crust found between base of the crust and top of mantle
mantle`
thickest layer of earth
-made up of semi molten rock (magma)
asthenosphere
upper part of mantle
inner core
hottest part of earth
-made of iron and nickel
continental crust
-thicker
-less dense
-less likely to be destroyed
oceanic
-thinner
-newer
-more dense
-more likely to be destroyed
tectonic hazards distribution
- close to plate margins
constructive plate boundary
- move apart
-creates a gap
-movement created by ridge push
ridge push
- magma rises through gap
-heats edges of plate - creating a raised ridge at the edge of each plate.
- lava cools to create new crust
-it becomes denser, gravity weighs down on the crust pushing it away from the boundary
Most constructive plate boundaries are found
at the bottom of the oceans.
- the plates move apart,
allowing magma to rise,
forming new oceanic crust. .
Volcano formation: constructive
- gap = hot magma can rise up.
-When magma reaches the surface it gently spills out onto the edge of the plates
The lava spreads out and cools creating wide shield volcanoes.
Earthquake formation: constructive
As the newly created crust cools and slides away from the ridge, it can fracture or crack triggering lots of gentle earthquakes.
destructive plate boundary.
Two plates move TOWARDS each other
- plates meet, ocean plate subducts
Earthquake formation: destructive
- ocean plate sinks = it rubs against the plate above (friction)
- the plates gets stuck.
- Pressure builds up until the plates suddenly unstick, the energy released creates seismic waves (an earthquake)
Volcano formation: destructive
- ocean plate sinks into the mantle,
the edge melts creating lots of extra magma. - This creates pressure to build in the mantle
- forces the magma through cracks in the crust.
=eruption
subduction zone
plates meet, the thinner, denser (heavier) ocean plate subducts (sinks) below the thicker continental plate,
destructive movement caused by
- Movement is created by slab pull.
-The sinking ocean plate is pulled further into the mantle by gravity as it is colder and denser.
This pulls the rest of the plate with it.
conservative plate boundary
Two plates move SIDE BY SIDE
- at different speeds
- As the plates scrape past each other it creates friction,
- causing the plates to become stuck.
- Pressure builds up in the plates, until the plates jolt apart.
- This releases seismic waves
-no volcanoes
Earthquakes focus
- The place in the crust where the plates jolt apart and release seismic waves
- this is where the earthquake begins.
- can be deep within the crust or shallow,
Earthquakes
- As the seismic waves travel through the crust,
- away from the focus, = they lose energy.
These waves make the ground shake
Earthquakes epicentre
- directly above the focus on the ground’s surface.
- The seismic waves reach the surface first at the epicentre,
- ground shakes most violently here + the earthquake will be strongest.
Richeter scale
The magnitude or strength of an earthquake is measured
The higher number on the Richter Scale, the higher the magnitude (strength).
primary impacts
occur immediately
secondary impacts
occur from hrs to days after initial earthquake
-follows primary impact
Tectonic hazards - primary impacts
- buildings collapse
- transport/communication lines disrupted
- gas/water pipes burst
- landslides
- animals flee
Tectonic hazards - secondary impacts
- tsunamis
- businesses lose income
- waterborne disease spread
-gov struggles with debt - homelessness
- unemployment = GNI lost
Immediate responses to natural hazards
- emergency shelters
- emergency services
- emergency food/water distributed
- repairs to sanitation
Long term responses to natural hazards
- roads are reconstructed
- buildings are repaired
-rebuilt to be safer
Nepal Earthquake impacts
- over 8000 ppl died
- 26 000 injured
- water tanks destroyed (infrastructure)
- homes lacked support so many collapsed
- 3.5 mill ppl made homeless
- no electricity
-ppl couldn’t be reached = hospitals fell
-tourism = collapsed as safety risks
Earthquake case study - NZ
- 185 deaths
- sewage piped damaged
- 170 000 homes ruined
-many relied on emergency services - tourism lost
Earthquake case study - Nepal’s immediate response
- Red cross sheltered 225 000 ppl
- water engineers helped build emergency toilets in rural
- 90% of army delivered aid on foot
- humanitarian aid offered
Earthquake case study - Nepal’s long term response
- 13 000 ppl displaced
- temporary camps
- rebuild schools
- housing reconstruction program to rebuild homes
-major repairs made
Earthquake case study - NZ immediate response
- emergency services sent out (helicopters)
- shelters opened
- 7 mil international aid
- red cross supplied workers
- 30 000 residents given chemical toilets
- clean water restored in 2 days
Earthquake case study - NZ long term response
- temporary housing
- gov 1 bil insurance claims
- gov funded construction of 10 000 homes to replace
- roads rebuilt
- rebuild Christchurch safer design
prediction
- using monitoring make educated guesses for hazards
- harder for earthquakes
planning
having preparations in advance of hazard
protection
- actions taken in advance to reduce impact of hazards
-build safer structures
Volcanic eruptions: prediction
- satellites monitor change in volcano shape
- seismometers to detect earthquake before
- heat sensors = change in temp
Volcanic eruptions: planning
- evacuation plan
- exclusion zones
- education of public
Volcanic eruptions: protection
- keep skin covered
-windows closed
-
Earthquakes: prediction
-seismologists = measure radon gas in groundwater as it escapes from cracks in crust
- measure tremors = seismometers
- locations/time are mapped to spot patterns
- GPS on phones
-detect movement further away before
- animals change in behaviour
Earthquakes: planning
-furniture fastened
- turn off main gas supply
- prepare supplies
- evacuation centres
- practice drills
-red cross + safety checklist to help plan
Earthquakes: protection
-design buildings = expensive
-strengthen rds
- hard to adapt building
- resistant buildings after need to be repaired/rebuilt
Living near to volcanoes - pros
- weathered lava = nutrient rich soil for crops
- geothermal energy
- magma contains minerals
- basalt in construction
- attract tourists
Living near to volcanoes - cons
- pyroclastic flow (fast flowing) = kills anything in its path
- tsunamis = flooding
- buildings destroyed = loss of income
- family live there
- ash affects breathing
- ash covers land
-kill ppl + damage property
Living near to Earthquakes - pros
- ppl can feel safe = properly built buildings
- offer jobs
- coastal areas = ports
Living near to Earthquakes - cons
- damage to infrastructure
-deaths - homes ruined
- land slides
-tsunamis - disease from polluted water
- destruction of business
