P1A Challenge of natural hazards Flashcards
define natural hazard
naturally occuring events that pose risk to human life+property
name three types of natural hazards
atmospheric: weather conditions
geophysical: movement of tectonic plates
hydrological: movement/distribution of water
examples of atmospheric hazards
tropical storms, extreme heat/cold, climate change
examples of geophysical hazards
volcanoes, earthquakes, tsunamis
landslides (both geo+hydro)
examples of hydrological hazards
flooding, landslides, drought
landslides (both geo+hydro)
factors affecting hazard risk (4)
- population density: more damage
- deforestation: increases risk of flooding/ landslides/ drought
- wealth: eg. LIC slums built in high risk areas prone to flooding, less capacity+funds to cope with disasters
- climate change: more extreme weather events, eg. rising temp causes tropical storms/drought, more rain causes flooding
plate tectonic theory (crusts + forces)
- earth’s crust divided into tectonic plates
- oceanic crust is thin+dense, whereas continental crust is thick+ less dense
- ridge push (constructive margins) pushes plates apart
- slab pull (destructive margins) - denser oceanic crust sinks under continetal crust due to gravity, pulls rest of plate with it
describe constructive plate margins +ex
- plates move apart by slab pull
- hot magma rises through gap
- magma cools+hardens, forms a new crust+ridge
- relatively gentle volcanic activity
eg. Mid-Atlantic ridge in Iceland - north american / eurasian plates
describe destructive plate margins (1 oceanic/ 1 continental) +ex
- denser oceanic plate sinks beneath continental plate
- plates jam, violent earthquakes occur when pressure is released
- oceanic plate melts underneath
- magma rises through continental plate - volcanic activity
eg. Ring of Fire around pacific plate, USA west coast etc.
describe destructive plate margins (2 continental)
- plates collide
- pressure causes ground to fold+push upwards
- fold mountains form
- causes earthquakes
eg. Himalayas - indian / eurasian plates
describe conservative plate margins +ex
- plates move past each other in different directions or speeds
- plates lock
- pressure is released - shockwaves
- earthquakes result on surface
eg. San Andreas fault - pacific / north american plates
describe global distribution of earthquakes +volcanoes
- occur together in narrow bands along plate boundaries
- anomaly: Hawaiian Hotspot in middle of Pacific plate - earthquakes
location+significance of earthquake in an LIC (cs)
Haiti, Caribbean 2010
* conservative plate margin
* magnitude 7.3, shallow earthquake
* epicentre near capital Port-au-Prince
* poorest country in the region
* secondary hazards: flooding, riots
* GDP $0.8T - 6x lower than Sendai
location+significance of earthquake in a HIC (cs)
Sendai, Japan 2011
* destructive plate margin
* magnitude 9.1, shallow earthquake
* epicentre near Sendai, close by Tokyo capital
* secondary hazards: tsunami
* GDP $4.9T - 6x higher than Haiti
primary effects of an LIC earthquake (cs)
Haiti 2010
* 230,000 deaths
* buildings collapsed: city cathedral, palace, airport control tower, government buildings
* water+electricity cut-off
* no internet/telephone signal
* sea port destroyed+unusable
secondary effects of an LIC earthquake (cs)
Haiti 2010
* Cholera outbreak - poor sanitation
* 70% jobs lost
* international airport+ trading port destroyed so no transport/communication/income
* people homeless or sleeping in street as afraid of collapsing buildings
* cost of damage $8.5B
primary effects of a HIC earthquake (cs)
Sendai 2011
* 10,000 deaths
* homes destroyed/collapsed
* people injured by falling debris
* electricity/energy supplies damaged
secondary effects of a HIC earthquake (cs)
Sendai 2011
* tsunami - 10,000 more deaths (total 20k)
* trains/ships swept away
* Fukushima nuclear power station explosion
* gas leaks caused fires
* cost of damage $309B
short-term responses for an LIC earthquake (cs)
Haiti 2010
* search teams, eg. from UK
* dig for survivors by hand
* international aid: UK search teams, food/water, medical supplies
* field hospitals set up
* temporary tent homes
long-term responses for an LIC earthquake (cs)
Haiti 2010
* reconstruct/repair buildings (poorly)
* port fixed
* charities/donations set up from HICs
* China donated £1M
short-term responses for a HIC earthquake (cs)
Sendai 2011
* evacuation sirens as warnings
* Tokyo evacuated
* rescue teams offered by other countries but NOT NEEDED
* 100,000 japanese troops sent, helicopters/police - search teams
* extinguish fires
* Fukushima nuclear power station explosion - 100,000 people evacuated
long-term responses for a HIC earthquake (cs)
Sendai 2011
* tsunami flood walls built higher as ineffective
* bodies identified
* tsunami warning system reviewed+improved
* reconstruction/repair of buildings - more resistant to earthquakes eg. cross-bracing
primary effects of volcanic eruptions
- lava/pyroclastic flow destroys structures
- disrupted comunication/transport links
- crops/water supplies contaminated by ash
- people killed by falling debris/ lava/ poisonous gases
secondary effects of volcanic eruptions
- acid rain - pollutants in air
- ash fall - stops flights, lowers global temp (climate change)
- lahars (after rainfall) mudslides
- diseases spread - poor sanitation
why people live in tectonic areas (5)
- farming - volcanic soil is fertile
- jobs are highly paid for being in high risk areas, eg. mining
- tourism - hot springs, volcanoes, views+ adventure
-> locals benefit from revenue - geothermal energy source - electricity
- family/friends - cheaper, easier to stay than move
how to reduce risks of a tectonic hazard (3P)
Prediction: monitoring tectonic activity, predict location but not time of event
-> limited as cannot predict intensity/severity of impacts
Protection: earthquake-resistant buildings: cross bracing, shock absorbers, shear walls, pyramid shape - less damage+ cost, eg. Japanese buildings after Sendai
-> Haiti/Philippines lack of resources so buildings reconstructed the same
Planning: practice drills in schools/workplaces - so people act calmly+quickly, eg. Sendai alarm warning system
-> relies on public compliance
describe the convection cell near the equator in northern hemisphere (why/how tropical storms form)
Hadley cell circulation
* warm/moist air rises from equator - belt of low pressure
* moisture condenses into clouds which move away from equator
* at 30 degrees N, cold/dry air sinks - high pressure, clear skies
* air moves back towards equator (low pressure)
tropical storms
* heat energy powers the storm (clouds)
* as more air drawn to low pressure area, coriolis force causes wind to spiral into the storm’s eye
* cold/dry air sinks into eye creating calm conditions
describe power of tropical storms inland vs at sea
- develop in middle of ocean (where its deeper) to get bigger+stronger
- prevailing wind pushes storms inland
- landfall+friction slow the storm down
describe how surface winds occur
air moving from an area of high - low pressure
greater difference causes stronger winds
describe global distribution of tropical storms
hurricanes: Atlantic ocean (west USA)
cyclones: Indian/ south Pacific oceans (India)
typhoons: North Pacific ocean (east asia)
conditions needed for tropical storms (3)
- ocean temp 27 degrees C +
- deep ocean 70m +
- between 5-30 degrees N/S of equator
-> not on equator due to absence of coriolis (spin) force (low pressure), and not past 30 as too cold
structural features of tropical storms (5)
- eye - calm conditions - cold/dry air
- eyewall
- anti-clockwise surface flow (northern hemisphere) - coriolis force
- warm/moist air - from warm water below (27+)
- around 1000km across
how is climate change affecting frequency/intensity/distribution of tropical storms
frequency: same or decrease as earth gets warmer, but storms will be more severe (category 4/5) + last longer
intensity: increase as sea temps rise - increased heat energy powering storms - higher rainfall+ stronger winds
distribution: increase as sea temps rise - able to develop in places further from equator as suitable conditions
location+significance of typhoon in an LIC +3Ps (cs)
Haiyan - Philippines, SE Asia, 2013
* category 5 - one of strongest
* path of storm accurately predicted days bfr - preparation/evacuation
->intensity underestimated - powerful storm surge
* lack of protection - buidlings+shelters not storm-proof
* planning - affected areas given emergency supplies
primary effects of a typhoon in an LIC (cs)
Haiyan 2013
* heavy rainfall
* strong winds - infrastructure damaged - hospitals/roads/airport (Tacloban) /homes
* 6,000 deaths
* power cuts - poor communication between islands
other:
* animals killed
secondary effects of a typhoon in an LIC (cs)
Haiyan 2013
* severe flooding due to heavy rain
* contaminated flood water (sewage) spread disease
* leached soil - farmland destroyed/ crops died - food shortage
* trees uprooted - loss of habitats
* oil barge destroyed - spill damaged coastal ecosystems
* migration inland - Manila capital population increase
* homelessness as houses destroyed
* loss of tourism+business - Tacloban airport gone
* 6m people lost source of income
other:
* heavy rainfall - landslides
* livestock killed - food shortage
immediate responses for a typhoon in an LIC (cs)
Haiyan 2013
* path of storm predicted+ warnings given days bfr
* 800,000 people evacuated to temp shelters
* £100m aid sent from foreign countries - supplies/food/electricity
-> distribution of aid was slow - large-scale damage to infrastructure/transport
* curfew - prevents looting
* police/military called
-> only 100 reported - poor communication between islands as power shortage etc
other:
* rescue survivors, treat in temp hospitals
* recover dead bodies - prevent disease
long-term responses for a typhoon in an LIC (cs)
Haiyan 2013
* no-build zone- prevents construction in high-risk areas eg. coastal - protection
* new disaster warning system developed - planning
* USA provided $90m for redevelopment - restored Tacloban water supply
* mangrove trees replanted
weather hazards experienced in UK (4)
heavy rain (Boscastle, 2004), drought/heatwaves (2019), extreme cold (beast from the east, 2018), thunder/storms (Arwen, 2021)
impacts of weather hazards experienced in UK (6)
- crop failure - higher food prices/ reliance on imports
- flooding from heavy rainfall
- human health - heatstroke, hypothermia
- damage to infrastructure - homes/transport/electricity
- travel disruptions
- injuries
evidence of UK weather becoming more extreme
temp in northern hemisphere has fluctuated in past 10,000 years
eg. 2014 was warmest year since 1910, but December was coldest month in over a century
-> increase in intensity of hazards because of climate change
natural evidence for climate change (4)
- ocean sediments - shows change in ocean temps
- tree rings - white summer growth vs dark winter dormant
- ice cores - analyse gas levels to see atmospheric composition
- pollen analysis - fossilised in lake/bog sediment
natural causes of climate change (3)
- orbital changes: from circular (higher temp) to elliptical (lower temp) - affects distance from sun
- volcanic activity: releases CO2 - greenhouse gas, traps sun’s heat, increases temp
-> SO2 particles (soot)- reflects rays - reduces temp - solar energy output: varies over time
-> last 50yrs output has decreased but temp is rising - rejected theory
human causes of climate change (3)
- burning of fossil fuels to generate energy - releases CO2 into atmosphere
- agriculture (livestock+ rice farming) - methane released by animals during digestion and by the decomposition of organic matter in flooded rice fields
- deforestation: less trees so less CO2 removed from atmosphere
effects of climate change on humans
drought: health problems, crop failure - food shortage, desertification - uninhabitable space so mass migration
flooding eg. coastal: unnhabitable (submerged) - mass migration/crowding
effects of climate change on environment
- melting ice caps - loss of polar habitats
- land ice melting - rising sea levels - loss of land habitats
- bleaching/destruction of marine ecosystems - extinction
- extreme weather events - unable to adapt - extinction
describe mitigation for managing climate change (4)
reducing causes by reducing emissions
* alternative energy production: nuclear, renewable eg HEP, instead of fossil fuels
* international agreements: reducing greenhouse gas emissions by a certain date, eg. UK carbon neutral by 2050
* carbon capture/storage: CO2 from industry/energy stored udnerground
* planting trees: reforestation, removes CO2 as they grow
describe adaptation for managing climate change (3)
manage risk of impacts
* changing agricultural systems: to work with changing temp+rainfall patterns, drought-resistant crops, irrigation uses less water
* managing water supplies: water meters, water-efficient appliances, reduces consumption, or increase supply by using more practices eg. desalination/ more reservoirs
* reduce risk of rising sea levels: hard engineering eg. sea walls for flooding, cheaper to raise houses on stilts etc
