Natural Hazards Flashcards
what is a natural hazard?
A natural event that threatens people or has the potential to cause damage, destruction and death.
natural risk
the probability or chance that a natural hazard may take place
earthquake
a sudden movement within the earth’s crust followed by series of shocks
plate margin
the margin or boundary between two tectonic plates
tectonic hazard
A natural hazard caused by the movement of tectonic plates (including volcanoes and earthquakes).
tectonic plate
a rigid segment of the earth’s crust that can float across the heavier semi-molten rock below
volcano
an opening in the earth’s crust from which lava, ash, and gasses erupt
primary effects
The initial impact of a natural event on people and property, caused directly by it, for instance, the ground buildings collapsing following an earthquake.
secondary effect
the after-effects that occur as an indirect effect of the eruption on a longer timescale
Monitoring
Recording physical changes, such as earthquake tremors around a volcano, helps forecast when and where a natural hazard might strike.
Nepal primary effects
Around 9000 people died and more than 22000 were injured
An estimated 800,000 buildings were damaged or destroyed
4 million people were left homeless
The cost of damage was over 5 billion
Roads and bridges were destroyed
Water tanks and pipes were destroyed, leaving 2 million people without water or sanitation
Nepal secondary effects
the earthquake triggered avalanches on Mount Everest which killed 18 people
Many mountain roads were blocked by landslides preventing emergency aid from reaching remote areas.
A lack of clean water caused outbreaks of typhus which killed at least 13 people
Nepal immediate response
India and China sent teams to help residents rescue people trapped by debris, but a lack of tools and machinery slowed down rescue efforts
Nepal Immediate response 2
People tried to recover the dead and treat the injured but damaged roads made it hard for emergency workers and aid to get through
Nepal immediate response 3
charities such as OXFAM provided medicine, food, and temporary water supplies.
the red cross set up emergency shelters for 130 000 families who had lost their homes.
Nepal long term response 1
The World Bank Group financed 500 million worth of projects to build earthquake-resistant housing, and repair roads and irrigation systems. some projects are still ongoing.
Nepal long term responses 2
The road to Nepal into Tibet was reopened 2 years after the earthquake, but many other routes remain damaged
Nepal long term responses 3
Many Heritage sites were reopened in June 2015 to encourage tourists back to the area
water supply is being restored, but two years after the event, many people still didn’t have access to clean water
Nepal Long Term responses 4
NGOs are working with residents to increase their resilience to disaster, for example by providing alternative energy sources
L’Aquila, Italy primary effects
308 deaths, 1500 injured
67 500 people homeless
15 000 buildings collapsed
L’Aquila, Italy immediate responses
Camps set up for homeless
Ambulances, fire services and army to area to help victims
Government money to repair gas, electricity
Free mobile phones to people who had lost homes
L’Aquila, Italy long term responses
New settlements built to house over 20 000 residents
Most of the city rebuilt
Investigation into building standards
primary earthquake effects
Property and buildings destroyed People injured or killed Ports, roads, railways damaged
Pipes (water and gas) and electricity cables broken
Primary volcano effects
Property and farmland destroyed People and animals killed or injured Air travel halted due to volcanic ash
Water supplies contaminated
secondary effects of earthquakes
Business reduced as money spent repairing the property
Blocked transport hinders emergency services
Broken gas pipes cause fire
Broken water pipes lead to a lack of freshwater
secondary volcanoes effects
The economy slows down. Emergency services struggle to arrive
Possible flooding if the ice melts Tourism can increase as people come to watch
Ash breaks down leading to fertile farmland
tectonic hazards immediate response
issue warnings if possible Rescue teams search for survivors Treat injured Provide food and shelter, food and drink Recover bodies Extinguish fires
tectonic hazards long term response
Repair and re-build properties and infrastructure
Improve building regulations
Restore utilities
Resettle locals elsewhere
Develop opportunities for recovery of the economy
Install monitoring technology
earthquakes constructive margins
usually, small earthquakes as plates pull apart.
Earthquakes at destructive margins
violent earthquakes as pressure build and is then released
volcano constructive margins
Hot magma rises between the plates eg. Iceland. Forms Shield volcanoes
Social effects of the big freeze
Several people died of hypothermia and accidents on icy roads
Water froze in pipes causing them to burst to lead to flooding. 40 000 homes without water for over a week
7000 schools closed in December leading to disruption
economics effects of the big freeze
Transport disrupted and some drivers trapped in cars for 15 hours
People could not get to work
Christmas shopping was affected
The estimated cost of damage due to lost business £1.6 billion (reducing GDP by 0.5%)
environmental impacts of the big freeze
Frost damaged crops esp. sugar beet
The use of gas and electricity increased increasing CO2 emissions
Management strategies
Gritters on roads to reduce accidents but supplies were limited
Warning to restrict travel to only essential journeys
Closing schools
Getting individuals to stock up on essential supplies
tropical storms
Occur in low latitudes between 5 and 30 degrees north and south of the equator. Ocean temperature needs to be above 27 degrees C. Happen between summer and autumn
social effects of climate change
increased disease eg. skin cancer and heat stroke
Winter deaths decrease with milder winters
Crop yields affected by up to 12% in South America but will increase in Northern Europe but will need more irrigation
social effects of climate change 2
Less ice in the Arctic Ocean increases shipping and extraction of oil and gas reserves
Droughts reduce food and water supply in sub-Saharan Africa. Water scarcity in South and South East UK
social effects of climate change 3
Increased flood risk. 70% of Asia is at risk of increased flooding
Declining fish in some areas affect diet and jobs
Increased extreme weather
The skiing industry in the Alps threatened.
environment effects of climate change
Increased drought in Mediterranean region
Lower rainfall causes food shortages for orangutans in Borneo and Indonesia
Sea level rise leads to flooding and coastal erosion
environmental effects of climate change 2
ice melts threaten habitats of polar bears
Warmer rivers affect marine wildlife
Forests in n America may experience more pests, disease, and forest fires
Coral bleaching and decline in biodiversity such as the Great Barrier Reef (Australia)
L’Aquila, Italy secondary effects
Aftershocks made the rescue more difficult
Fires caused damage in collapsed buildings
Broken waterpipes led to landslides
volcano destructive margins
an oceanic plate subducts under a continental plate. Friction causes the oceanic plate to melt and pressure forces magma up to form composite volcanoes eg the Pacific Rim
- describe tectonic plates
the earths crust is split into seven major and several monor tectonic plates
there are two types of crust- dense, thin oceanic crust and less dense, thicker continental crust plates move , drivewn by convection currents within the mantle and inder gravity
- what happens at the different plate margins
plates seperate at constructive margins forming new crust, causing volcanic erruptions
plates collide at destructive plate margins eruptions and fold mountains plates side by side each other at conservative margins causing earthquakes
- descrube the distribution of volcanoes
volcanoes are large, often cone shaped landforms, formed over long periods by several erruptions. they are fed by molten rock deep within the earths mantle. Like earthquakes most volcanoes occur in belts along plate margins. But some occur at hot spots where the crust is thin and magma breaks through the surface
- describe contructive margins
the two plates move apart and magma forces its way to the surface. As it breaks the crust it causes mild earthquakes. the magma is very hot and fluid allowing the lava to flow a long way before cooling. this results in typically broad and flat shield volcanoes
- describe destructive margins
two plates move towards each other. Here the dense oceanic plate is subducted beneath the less dense continental platel. friction causes strong earthquakes. the sinking oceanic plate creates sticky, gas-rich magma. this results in steep- sided composite volcanoes which erupt violently.
where two continental plates meet there is no subduction, so no magma to form volcanoes. the crust crumples and lifts to form fold mountains. Powerful earthquakes can be triggered
- describe conservative plate margins
two plates move past each other at different rates. friction between the plates build stresses and trigger earthquakes when they slpi, there are no volcanoes because there is no magma.
- why people live at risk from tectionic hazards
poor people have no choice- money, food and family are seen as more important
plate margins often coincide with favourable areas for setllement and trade some people have no experience or knowledge of the risks 7 earthwuake fault lines can allow water to reach the surface- important in arid regions effective monitoring of volcanoes and tsunami waves allow evacuation warnings to be given earthquake resistant building designs reduce risk earthquakes and volcanic erruptions are rare, so not seen as a great threat
- describe living on a plate margin: iceland
Iceland straddles the Mid-atlantic ridge with volcanic erruptions on average every five years. But awareness and monitoring reduces the threat to low risk. indeed, the tectonic activity brings hiuge benefits such as hellisheidi combined heat and power plant which serves reykjavik
- describe the Hellishieldi plant
naturally occuring hot water and superheated steam provides hot water and central heating for 90% of buildings. including greenhouses and swimming pools
volcanic rocks are used in road and building construction icelands dramatic landscapes with water falls, hot springs, greysers, lava fields, volcanoes and glaciers support hige tourism industry geothermal energy- generates 25% og icelands electricity
- how can risks from tectonic hazards be reduced
monitoring
prediction protection planning
- describe monitoring in volcanoes and earthquakes
all volcanoes are now monitoring using hi tech scientific equipment
remote sensing- satelites detect heat increases siesmicity- siesmographs recrod microearthquakes ground deformatio- laser beams measure changes in the shape of the ground earthquakes generally occur without warning. a number of events can occur before an earthquake strikes, but these are never sertain enough to issue warnings microearthquakes before the main terror bulging of the ground raised groundwater levels
- describe prediction in volcanoes and earth quakes
monitoring is now allowing accurate prediction oand effective evacuatio
accurate predictions are impossible with earthquakes due to a lack of clear warning signs. But historical records can help determine probablity and so help in planning for them
- describe protection in volcanoes and earthquakes
little can be done to protect property , but earth embankments and explosives have been used to successfully divert lava lflows
eathquake drills help keep people alert and prepared. but earthquake resistant construction is the best way to reduce risk
- describe planning in volcanoes and earthquakes
risk assesments and hazard mapping to identify areas to practice evacuation or restrict building
risk assesment and hazard mapping to identify areas to protect buildings and infrastructure
