The Challenges Of Natural Hazards Flashcards
What are natural hazards
Physical events such as earthquakes and volcanoes that have the potential to do damage to humans and property.
What affects hazard risk?
-population growth
-climate change
-deforestation
-LIC’s are at more risk because they don’t have the money to protect themselves
Structure of the earth
-the core
-mantle
-crust
Crust
Split into major sections called tectonic plates.
Crust
-oceanic and continental crust
-these plates move due to convection currents in the mantle and where they meet volcanoes and earthquakes occur.
Margins
-destructive when they move towards each other
-constructive when they move away from each other
-conservative when they move past each other
Volcanoes
Constructive margin - hot magma rises between the plates
Destructive margin - an oceanic plate subducts under a continental plate to melt and pressure forces magma up to form composite volcanoes
Earthquakes
Constructive margin - small earthquakes as plates pull apart
Destructive margin - violent earthquakes as pressure builds and is then released
Conservative margin - plates slide past each other. They catch and then as pressure increases it is released
Primary and secondary effects of earthquakes
Primary- property of buildings destroyed
- people injured or killed
- damaged services
-water, gas and electricity broken
Secondary- money lost repairing buildings
-blocked transport
-broken gas pipes cause fires
-broken water pipes lead to lack of fresh water
Primary and secondary effects of volcanoes
Primary- property and farms destroyed
-people and animals killed and injured
-water supplies contaminated
Secondary- emergency services struggle to arrive
- ash breaks down leading to fertile land
Immediate responses to hazards
-issue warnings
-rescue teams
-treat injured
-provide shelter
-extinguish fires
Long term responses to hazards
-repair and rebuild properties
-restore utilities
-resettle locals elsewhere
Distribution of tectonic activity
Along plate boundaries on the edge of continents and around the edge of the pacific.
Monitoring
Seismometers measure earth movement.
Volcanoes give off gases
Prediction
By observing monitoring data, this can allow evacuation before event.
Protection
Reinforced buildings and making building foundations that absorb movement.
Automatic shut offs for gas and electricity.
Planning
Avoid building in areas at risk.
Training for emergency services and planned evacuation drills.
Nepal earthquake 2015 April - primary effects
-magnitude 7.8
-9000 deaths
-23000 injured
-500,000 homes destroyed
-26 hospitals destroyed
-50% of schools destroyed
Nepal earthquake- secondary effects
-avalanche on mountain killing 19 people
-loss of tourism and income
-food shortages
Nepal - immediate response
-raised $126 million
-red cross
-requested international help
-tents for 225,000 people
Nepal - long term response
-international conference to discuss reconstruction
-tourist attractions reopened
Global atmospheric circulation
At the equator the suns rays are most concentrated this means it is hotter.
High pressure = dry
Low pressure = wet
As the air heat rises - causing low pressure as it cools it sinks causing high pressure. Winds move from high pressure to low pressure. They curve because of the coriolis effect.
Tropical storms
In low latitudes between 5 and 30 degrees north and south if the equator. Ocean temperatures needs to be above 27 degree and between summer and autumn.
Sequence of a tropical storm
-Air is heated above warm tropical storms.
-Air rises under low pressure conditions
-strong winds form as rising air draws in more air and moisture causing torrential rain
-Cold air sinks in the eye so it is clear and dry
-heat is given off as it cools powering the storm
-on meeting land it loses source of heat and moisture so loses power
Climate change will affect tropical storms to. Warmer oceans will lead to more intense storms – but not necessarily more frequent ones