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Geography > Natural Hazards > Flashcards

Natural Hazards Flashcards

1
Q

definition of a natural hazard

A

extreme natural events that can cause loss of life, extreme property damage and disrupt human activities

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2
Q

what is a METEOROLOGICAL natural hazard

A

atmospheric, eg tropical storms

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3
Q

what is a GEOMORPHIC natural hazard

A

occur on the Earth’s surface, eg. flooding

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4
Q

what is a TECTONIC natural hazard

A

Involves movement of tectonic plates in the earths crust, eg, earthquakes or tsunamis

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5
Q

what is a BIOLOGICAL natural hazard

A

involves living organisms eg. forest fires

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6
Q

how does MAGNITUDE affect risk?

A

(strength) size affects impact

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7
Q

how does FREQUENCY affect risk?

A

How often hazard occurs. more often = more prepared, adjust buildings and lives

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8
Q

how does DEVELOPMENT affect risk?

A

money available to prepare and respond to event. HICs better (more money/ tech, planning)

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9
Q

how does POPULATION DENSITY affect risk?

A

no. of people in area. more people = increased potential for disaster

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10
Q

how does EDUCATION affect risk?

A

people can be educated on how to survive NHs. saves many lives

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11
Q

how does NATURAL FACTORS affect risk?

A

e. g rock type in eq, shape of coastline.
- gently sloping coastline = increased damage in hurricane
- soft rock = larger and longer eq. more likely to collapse

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12
Q

how does MANAGEMENT affect risk?

A

some are easier to predict/ prepare for

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13
Q

describe the OCEANIC CRUST

A
  • thinner and denser (5-10 km)
  • basaltic rock
  • SINKS when meets continental plates
  • less than 200 mill years old (young)
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14
Q

describe the CONTINENTAL CRUST

A
  • thicker (20-200km)
  • granite rock
  • up to 3.8 bill years old
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15
Q

CONVECTION CURRENTS

A
  • magma rises in mantle.
  • as it rises further from core, it cools and sinks.
  • creates a current which moves plates with it.
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16
Q

what is ridge push?

A
  • at constructive margins, ocean ridges form.
  • beneath, mantle melts.
  • molten magma rises as plates move apart and cool to form new plate material.
  • as lithosphere cools = denser and slides down away from ridge causing plates to move away from each other = ridge push.
17
Q

what is slab pull?

A

at destructive margins denser plate sinks back into mantle under gravity. pulls rest of plate with it = SLAB PULL

18
Q

what happens at a CONSTRUCTIVE MARGIN?

A
  1. upper part of mantle melts and hot molten magma rises
  2. tectonic plates are moved away from each other. releases pressure and molten magma rises between
  3. it cools to form a solid rock. as the rich cools it becomes denser and sinks, causing tectonic plates to move further (ridge push)
  4. in a few places magma erupts onto surface producing runny kava that spreads out before solidifying, over many eruptions a shield volcano is formed
19
Q

what happens at a conservative margin?

A
  1. occurs when plates move parallel to each other
  2. the 2 plates can move side by side, either :
    - in the same direction but different speeds
    - in opposite directions
  3. earthquakes are found because pressure builds up as a result of friction between plates. eventually rock fractures and pressure is released = eq
20
Q

what happens at a DESTRUCTIVE MARGIN?

A
  1. occurs when tectonic plates move towards each other and collide
  2. if 2 continental plates collide, they are both buoyant and cannot sink into the mantle therefore form mountains
  3. if oceanic + continental collide the denser oceanic plate is SUBDUCTED and sinks under continental plate
  4. as the plates converge pressure builds up. the rocks eventually fracture causing an earthquake. when the oceanic plate subdues, it pulls the rest of the plate along, causing a deep ocean trench on the surface
  5. as the oceanic plate sinks deeper into the mantle, it causes part of the mantle to melt. eventually it erupts, forming composite volcanoes
21
Q

what were the PRIMARY IMPACTS of the Nepal EQ?

A
  • buildings collapsed
  • 8800 dead and 16800 injured
  • 26 hospitals and 50% of schools destroyed
  • 1.5 mil needed food and water
22
Q

what were the SECONDARY IMPACTS of the Nepal EQ?

A
  • avalanches
  • death toll 9000
  • landslides, nearly 400,000 cut off from outside assist
  • fall in tourist no. = less money, tourism 10% of GDP
  • EQ happened before monsoon. rice seeds destroyed = affecting harvest
  • 3% more pushed into poverty
23
Q

what was the RESPONSE of the Nepal EQ?

A
  • international aid and search and rescue teams
  • medical supplies and field hospital
  • 9 helicopters rescued people from Everest
  • $274 mill aid pledged by EU japan Us
  • money spent on rebuilding, repairing and clearing roads
  • heritage sites reopened encouraging tourists
24
Q

why were the impacts of the Nepal EQ so bad?

A

LIC, cannot afford protection eg, eq safe houses

  • can’t afford to rebuild
  • tourism affected
  • food supplies destroyed
25
Q

summarise the Nepal earthquake

A

P- people killed, buildings collapse
S- lack of housing equipment + medicine
I- shelters/ tents, searching for survivors, food handing out
LT- no taxes, temporary houses, rebuilding

26
Q

what were the PRIMARY IMPACTS of the Christchurch EQ?

A
  • 185 killed, 2000 inj
  • 2 buildings collapsed killing most
  • 10000 buildings needed to be demolished after , 50% severely damaged
  • liquefaction, damaged to roads and buildings
  • hundreds of km water and sewage pipes damaged
  • 80% without electricity
  • numerous aftershocks
27
Q

what were the SECONDARY IMPACTS of the Christchurch EQ?

A
  • businesses put out of action, cost $40 mill and 50000 jobs
  • no longer host RWC = lost income and tourism
  • damage to roads due to liquefaction. made it hard for emergency services to move around
  • another 1293 were injured in the aftermath
  • psychological and financial impacts
28
Q

what was the RESPONSE of the Christchurch EQ?

A
  • ‘farmy army’ brought machinery to clean up city
  • local councils out emergency response plans into actions
  • international aid $6-7 mil and aid workers
  • areas zoned into safe and unsafe
  • chemical toilets provided
  • roads and houses cleared of silt
  • temporary houses provided
  • rebuild stronger houses
  • non-government organisations (save the children eg) helped w/ recovery
29
Q

why were the impacts of the Christchurch EQ less bad?

A

HIC- has access to money, equipment, recovery + prevention strategies. nepal doesn’t

30
Q

what are the 4 reasons people live in tectonic areas?

A
  1. TOURISM - eg, Yellowstone. provides good jobs and views
  2. FARMING - land more fertile near volcanoes. provides valuable income
  3. GEOTHERMAL ENERGY - heat + hot water 90% of homes. geothermally heated greenhouses (income). steel produced (income + eco)
  4. EMOTIONAL TIES - family and friends
31
Q

how can PROTECTION reduce tectonic risks?

A
  • actions taken before a hazard strikes to reduce its impacts
  • eg. improving building designs / eq drills
  • prevents damage from happening in 1st place
32
Q

how can PREDICTION AND MONITORING reduce tectonic risks?

A
  • scientists sometimes estimate when/ where a hazard may happen. use historical evidence and monitoring
  • eg. eq tremors around a volcano
  • means people can evacuate/ take measures to decrease impacts
33
Q

how can PLANNING reduce tectonic risks?

A
  • actions taken to enable communities to respond to and recover from natural disasters
  • e.g. emergency evacuation plans + warning systems
  • all are aware of what to do in a crisis, reducing deaths

Geography (3 decks)

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