Paper 1: Global Hazards Flashcards
What were the social impacts of tropical cyclone Aila on Bangladesh?
- Several villages destroyed by a storm surge
- 190 people killed
- 750,000 made homeless
What were the economic impacts of tropical cyclone Aila on Bangladesh?
- Embankments washed away
- A lot of crops killed by salt water
- 59,000 animals (including livestock) killed
What were the environmental impacts of tropical cyclone Aila on Bangladesh?
- Loss of animals (no animal dung source of cooking fuel) which led to deforestation for firewood
- Sickness (fresh water contaminated)
- Endangered tigers drowned
How does Bangladesh prepare for cyclones?
- Weather forecasting
- Satellite technology
- Warning systems
- Evacuation strategies/shelters
Pros and cons of weather forecasting in Bangladesh
Pros:
- In 2009 there were lower death rates for those households with radios
- In the capital city of Dhaka, many people have TVs and radios
Cons:
- There are only 50 phones per 100 people in 2014
Pros and cons of satellite technology in Bangladesh
Pros:
- Enables accurate and quick tracking
- Can track cyclones
Cons:
- It’s expensive
Pros and cons of warning systems in Bangladesh
Pros:
- There are over 45,000 cyclone warning volunteers spreading awareness and information
Cons:
- Some people are illiterate and can’t read the posters and leaflets
- Some people don’t pay attention to them due to previous false warnings
Pros and cons of evacuations strategies/shelters in Bangladesh
Pros:
- People who use them usually survive
- 3500 built
Cons:
- More are needed
What are the 4 natural causes of climate change?
- Volcanic eruption
- Sunspot theory
- Orbital theory
- Surface impact (asteroid)
How do volcanic eruptions contribute to climate change?
They produce ash and gas that spread and form huge clouds (like a blanket) which stops sunlight from reaching the earth’s surface, making it colder
How does the sunspot theory contribute to climate change?
Sunspots are black areas on the sun’s surface and more of them means that more solar energy is being fired from the sun towards earth which makes the temperature on earth warmer but fewer sunspots make it cooler
How does the orbital theory contribute to climate change?
Over very long timescales, there have been big changes in climate and scientists think they are due to the way the earth orbits around the sun - sometimes it’s circular (meaning it’s closer to the sun) but sometimes it’s more ecliptal (oval shaped, meaning further away from the sun)
How do asteroids (surface impact) contribute to climate change?
Asteroid impacts can only alter the earth’s climate if they’re big, blasting millions of tonnes of dust and ash into the atmosphere causing the climate to cool as dust blocks the incoming sunlight
What level cyclone was cyclone Aila (Bangladesh)?
1
What level hurricane was hurricane Katrina (USA)?
3
How was the preparation for the cyclone different in Bangladesh vs the USA?
In Bangladesh an estimated 500,000 (only around 25% of the population) people were evacuated whereas in the USA, 80% of the population left
How was the response to the cyclone different in Bangladesh vs the USA?
- In Bangladesh, the Red Cross supplied water purifying tablets (NGOs also distributed dry clothes) and water was rationed so everyone had something to drink but in the USA, people in the superdome were trapped with limited food and water
- The government set up camps for people to stay and NGOs started teaching people to design cyclone proof houses (although they were quite expensive) however in the USA, FEMA (the Federal Emergency Management Agency) were unprepared for the scale of destruction causes
What is the greenhouse effect?
The sun’s energy passes through the atmosphere in short wave radiation. The energy deflects from the earth as long wave radiation. Some energy is trapped by the atmosphere while some escapes. As more greenhouse gases are released, the atmosphere becomes thicker. This causes more of the radiated energy to become trapped and the climate of the planet increases.
What are the human causes of climate change?
- Deforestation (releases CO2)
- Transport (releases greenhouse gases)
- Factories (burn fossil fuels)
- Cattle ranching (produces methane)
What evidence is there for climate change?
- Tree rings
- Ice cores
- Sediment cones in the oceans
- Thermometer (instrumental records)
How do tree rings show climate change?
- Each ring represents a year of growth
- The thicker the rings, the warmer and wetter the conditions
- The thinner the rings, the colder and drier the conditions
How do ice cores show climate change?
- CO2 bubbles in the ice
- More CO2 can infer warmer temperatures (stronger greenhouse effect)
How do sediment cones show climate change?
- Micro fossils of creatures in the ocean
- Amount of warm/cold loving species infers the climate
How do thermometers (instrument records) show climate change?
- It’s a recent thing (past 100 years)
- Accurate readings of past climate
Why might it be difficult to predict future climate change?
- Population growth (more or less energy used?)
- Level of development (richer or poorer nations?)
- Emissions (continued use of fossil fuels?)
- Natural processes (could these change?)
What was the magnitude of the Haiti earthquake?
7 (aftershocks were 5.5 and 6)
What was the magnitude of the Japan earthquake?
9
How were the primary impacts different in response to the earthquake in Haiti vs Japan?
In Haiti, 316,000 people were killed and 180,000 homes were destroyed whereas in Japan, 1500 people were killed and 1000 buildings damaged due to liquefaction
How was the short term management different in response to the earthquake in Haiti vs Japan?
In Haiti, the response to the earthquake was poorly managed due to a lack of funding whereas in Japan, rescue workers and the army were mobilised to deal with the crisis
How were the secondary impacts different in response to the earthquake in Haiti vs Japan?
In Haiti, there was a cholera outbreak due to lack of clean water and sanitation but in Japan, 17,000 more people died due to a tsunami
How was the long term management different in response to the earthquake in Haiti vs Japan?
In Haiti, 75% of the damaged buildings were inspected and repaired using earthquake proof methods (such as making a lighter roof out of leaves or bamboo) whereas in Japan, all new buildings had to adhere to a strict building code which limit them from collapsing and killing people
What is the structure of the earth?
- Lithosphere (Crust, upper mantle)
- Asthenosphere
- Mantle
- Outer core
- Inner core
What are the properties of the lithosphere?
- 80-100 km (thinner under oceans)
- Crust is made of tectonic plates
- The crust moves on top of the asthenosphere
What are the properties of the asthenosphere?
- Dense and mobile
- 100-700 km
What are the properties of the mantle?
- The lower layer is liquid magma (3000 degrees celsius)
What are the properties of the outer core?
- Liquid
- Made from iron and nickle
- 4000-6000 degrees celsius
What are the properties of the inner core?
- Solid due to high pressure
- Made from iron
- 5000-6000 degrees celsius
What are convection currents?
- Heat from inside the earth is called geothermal energy
- The heat is produced by radioactive decay of elements such as uranium and thorium in the core and mantle - this process gives off heat and raises the core’s temperature to over 5000 degrees celsius
- Convection currents transfer heat - in the earth’s mantle, the currents which rise from the earth’s core are strong enough to move tectonic plates on the earth’s surface
What are the 2 different types of crust?
- Oceanic
- Continental
What are the properties of the oceanic crust?
- 5-10 km thick
- Younger
- Denser
- Can be destroyed (subduct)
- Basalt
What are the properties of the continental crust?
- 30-50 km thick
- Older
- Less dense
- Cannot be destroyed
- Granite
What are the types of 4 plate boundaries?
- Convergent/Destructive
- Divergent/Constructive
- Conservative/Transform
- Collison
What are convergent/destructive plate boundaries?
- Convection currents drag plates together
- Oceanic plate is denser so gets subducted
- Oceanic plate is superheated, melts, and magma fills the magma chamber
- Friction between plates leads to earthquakes
- A deep trench is formed where plates meet
What are divergent/constructive plate boundaries?
- 2 oceanic plates move away from each other
- This is caused by convection currents
- Both plates being oceanic means they have similar densities
- Magma pushes upwards, creating land above sea level
What are conservative/transform plate boundaries?
- Plates move past each other at different speeds
- Friction between the plates causes the plates to get stuck
- Pressure builds up then releases, causing an earthquake
What are collision plate boundaries?
- Another type of convergent plate boundary (plates move towards each other)
- Pressure builds up and then releases, causing an earthquake
- As they push together, they crumple into mountain ranges
What are the features of a composite volcano?
- Andesitic magma (cooler, explosive, sticky, viscous, acidic)
- Steep sides as lava doesn’t flow very far before solidifying
- Layers of ash and lava
- Less frequent, more violent eruptions
What are the features of a sheild volcano?
- Basaltic magma (hot, non-acidic, runny, not explosive)
- Gentle sides as lava flows for long distances before it solidifies
- No layers, only lava
- Less violent, more frequent eruptions
How are volcanic hotspots formed?
- A plume of superheated rock rises slowly through the mantle
- Once it reaches the upper mantle, it causes the base of the crust to melt
- The magma produced then rises through weakness in the crust and erupts at the earth’s surface
- The plumes are fixed in place
Why do people live near volcanoes?
- Minerals
- People may not have money to move elsewhere
- Fertile land for agriculture
- Geothermal energy
- Tourism (working in tourism and also people visiting)
- It’s often beautiful
What is needed for tropical cyclones to form?
- Warm water (ocean temperatures over 26.5 degrees celsius for an extended period of time)
- Strong winds (10-12 km above the surface to draw warm winds upwards quickly)
- Coriolis force (the spinning force created by the earth’s rotation makes cyclones form - usually between 5-30 degrees north and south of the equator)
