The Challenges of Natural Hazards Flashcards
What is a natural hazard?
A natural event that threatens people or has the potential to cause damage, destruction, and death
What is a natural disaster?
A natural hazard that has happened
What are the two types of natural hazards, and give examples.
Geological (caused by tectonic plates movement)
eg. earthquakes, volcanoes, avalanches
Meteorological (involving weather, atmosphere and climate)
eg. heatwaves, hurricanes or bushfires
What are 3 factors that affect how bad a natural hazard is?
- Frequency
- Magnitude
- Predictability
What are risks of a natural disaster?
- opulation density
- ability to cope/deal with events
- money for protection
- risk of area
Why do people live in high risk areas?
- can’t predict magnitude, timing or location
- can’t move due to expenses, language barrier, or knowledge
- worth staying for resources, jobs and prices
- don’t want to go as they’re optimistic/overconfident
What are the 3 layers of earth?
(inside to out)
- Inner metallic core (solid) = hottest part
- Outer core (liquid)
- Mantle = semi-molten rock
- Crust = very thin and broken into large pieces called tectonic plates
What is the lithosphere?
The rigid outer layer of the Earth, made up of the crust and the uppermost part of the mantle
Describe the oceanic plate.
- thin (5-10km)
- dense
- young (less than 200 million years old)
- sinks when with continental
- recycled at destructive margins
Describe the continental plate.
- thick (20-200km)
- less dense
- up to 3.8 billion years old
- granite rock
- not destroyed
What is a plate margin/boundary?
Location on Earth where 2 tectonic plates meeet or are next to each other
What is convection current?
- the cyclical movement of fluids caused by temperature and density differences
- happens in upper mantle, the heated molten rock rises and hits the underside of the plate, dragging the tectonic plates
What happens at a constructive plate margin?
PLATES MOVE APART
- this causes a gap where magma rises up to fill the gap, this cools to form solid rock
- forming part of the oceanic plate.
- magma can also form a shield volcano
What happens at a destructive plate margin?
(oceanic + continental)
PLATES MOVE TOWARDS EACH OTHER
- oceanic plate slides beneath continental (subduction zone)
- rocks get stuck on each other and pressure builds up, oceanic plate melts and magma can escape through a composite volcano
-until they slip past each other
What happens at a destructive plate margin?
(continental + continental)
PLATES MOVE TOWARDS EACH OTHER
- two continental plates form fold mountains
- pressure builds up
- until they slip past each other
What happens at a conservative plate margin?
PLATES SLIDE PAST EACH OTHER
- they get stuck and friction/pressure builds up
- until they slip past each other
Which plates margins cause volcanic eruptions?
Constructive and destructive (o+c)
Which plates margins cause earthquakes?
ALL (constructive is weak)
What is a hotspot?
Hotspots are places where the magma rises up through the crust
What is the ring of fire?
The ‘ring of fire’ is a group of volcanoes that are located along the plate margin of the Pacific plate
What 4 things do volcanos produce?
- Pyroclastic flows (superheated lava, gas and ash moving 500km/h)
- Ash (burnt rock fragments)
- Gases (like sulfur)
- Lava (magma at surface)
What are primary effects of volcanic activity?
- crop/livestock death
- human deaths
- damaged building/houses
- cause suffocation
- ash everywhere
- pyroclastic flows
- lahars (mud flows of water + ash)
What are secondary effects of volcanic activity?
- famine/starvation
- decreasing population
- homelessness
- disrupting local economy + tourism
- increased soil fertility + volcanic winter
What are immediate responses of volcanic activity?
- warnings and monitoring
- aids, charities and donations
- temporary infrastructure providing shelter, food, water, electricity
- rescued people
What are long-term responses of volcanic activity?
- improve local economy by encouraging tourists
- relocation, resettlement programs
- rebuilding infrastructure, transport, power and homes
What are the 3 aspects of an earthquake?
- Focus = where pressure is released
- Shock waves = most damage, aka seismic waves
- Epicentre = point directly above the centre of earthquake
What is the magnitude scale?
How much energy it releases, the richter scale is logarithmic (goes up in tens)
What are primary effects of earthquakes?
- ground shaking, buildings collapse
- ground rupture (split)
- injuries, deaths
- infrastructure damage
What are secondary effects of earthquakes?
- water contamination, diseases (cholera)
- power outages
- tsunamis/landslides
- economic loss
- fires
What are immediate responses of earthquakes?
- rescue operations
- dead bodies disposed to prevent diseases
- aid, charities, donations
- temporary infrastructure, providing shelter, food, water etc
- evacuation/warnings
What are long-term responses of earthquakes?
- improved preparation to withstand future earthquakes
- improve local economy by encouraging tourists
- rebuild infrastructure
When and where did the Chile earthquake occur?
February 2010, on the coast
What was the magnitude of the Chile earthquake?
8.8 on the Richter scale
What were the primary effects of the Chile earthquake?
- 500 killed
-12,000 injured - 220,000 homes destroyed
- $30 billion damage.
What were the secondary effects of the Chile earthquake?
1500km of roads damaged by landslides, tsunami caused coastal flooding.
What were the immediate responses to the Chile earthquake?
- emergency services acted quickly
- international help provided field hospitals
- temporary repairs to highway
What were the long-term responses to the Chile earthquake?
- government launched housing reconstruction plan
- economy rebuilt without much foreign aid
When and where did the Nepal earthquake occur?
April 2015, near Kathmandu, Nepal.
What was the magnitude of the Nepal earthquake?
7.9 on the Richter scale
What were the primary effects of the Nepal earthquake?
- 9000 killed
- 20,000 injured
- 8 million affected
- $5 billion damage (over 50% of shops and homes destroyed)
What were the secondary effects of the Nepal earthquake?
- Avalanches on Mount Everest killed 19
- landslides blocked roads
- shortage of water and electricity
What were the immediate responses to the Nepal earthquake?
- Search and rescue teams
- international aid and helicopters
- half a million tents provided.
What were the long-term responses to the Nepal earthquake?
- Roads repaired
- over 7000 schools rebuilt
- stricter building codes enforced.
Compare the primary effects of the Chile and Nepal earthquakes.
Chile: 500 deaths, $30bn damage. Nepal: 9000 deaths, $5bn damage.
Compare the secondary effects of the Chile and Nepal earthquakes.
Chile: Tsunami and landslides. Nepal: Avalanches, landslides, and blocked roads.
Compare the immediate responses of the Chile and Nepal earthquakes.
Chile: Quick emergency response, major highways repaired. Nepal: International aid, tents, and helicopters.
Compare the long-term responses of the Chile and Nepal earthquakes.
Chile: Strong economy allowed independent rebuilding. Nepal: Relied on international aid, building codes improved.
What are the 4 things to reduce the impact of tectonic hazards?
- Monitoring
- Predicting
- Protection
- Planning
Give examples of Monitoring.
- using seismometers to detect movement (saving lives)
- monitoring volcanos is easier because of the oozing, gas emissions and magma
Give examples of Predicting.
- looking at tectonic plate boundaries to know where they’re likely
- difficult to predrict
Give examples of Protecting.
- HIC’s can invest in earthquake-proof buildings, fire resistant materials and shock absorbers to reduce damage
- LIC’s use a lighter roof material (bamboo) to reduce damage if collapsed
- automatic switches turn off electricity/gas
- drills to education people
Give examples of Planning.
- HIC’s have warning systems and evacuation plans
- police, paramedics and firefighters trained
- governments can stockpile supplies and education people
Why do people still live in areas of risk?
- fertile land, good for farming and producing high yield
- good government, good evacuation/regulations
- family in area
- jobs/cost
- unaware of risks
