P1A Challenge of natural hazards Flashcards
(48 cards)
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
* 200,000 deaths (x100 more)
* 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