Studied by 3 peopleHazardous Earth
Climate
Tropical Cyclones
Tectonic Hazards
Climate
No case studies
Atmospheric Circulation
Air moves in a global pattern of circulation that transfers heat around the earth
Solar radiation
Drives our climate system. The suns rays heat earth, which in turn heats the air
Air pressure
The force or weight that the atmosphere exerts on earth
Low pressure
Where warm air is rising - creates unsettled weather and rainfall
High pressure
In areas of high atmospheric pressure air is sinking creating settled dry conditions
Wind
Is air moving from low to high pressure
Coriolis effect
The rotation of earth causes wind to follow a curved path
ITCZ
The intertropical convergence zone - is the band around the equator that receives the most concentrated solar radiation moves up and down throughout the year due to the tilt of the earth
Circulation cells
The polar, ferrel and hadley cells are the names of the main convection currents in the atmosphere
Hadley cell
Warm moist air rises at the ITCZ creating a band of low pressure rain and tropical rainforests at 30’ north or south the air cools and sinks creating a band of high pressure and arid deserts
Jet stream
Fast flowing rivers of air in the upper atmosphere that form between the polar and ferrel cells
Oceanic circulation
Convection currents also exist in the ocean e.g. the gulf stream impacting climates around the world
Climate change
The average climatic conditions of the planet vary over time earths climate has been through many cycles of natural cooling and warming in its 4.5 billion year history
Milankovitch cycles
Changes in the earths orbit affect the energy we receive from the sun e.g.
eccentricity - circular orbit = warmer earth , elliptical orbit = colder earth
axial tilt - when earth is more tilted, more extreme conditions
Other natural causes of climate change
Solar variation - changes in the amount of energy the sun produces
Volcanic eruptions - ash in atmosphere blocks out solar radiation
Asteroid collisions - also causes huge amounts of dust in the atmosphere
Evidence for natural climate change
Ice cores - analysing air bubbles trapped in ancient ice sheets in greenland allows us to see how atmospheric CO2 levels have changes
Tree rings - in warmer and wetter climates the space between rings widen
Historical sources - historical painting, diaries and records provide more evidence
The greenhouse effect
Natural processes that keep the earth warm enough to sustain life. greenhouse gases in the atmosphere (e.g. carbon dioxide, methane) trap some of the suns heat and stop it from being lost to space
The enhanced greenhouse effect
Human activity has greatly increased the amount of greenhouse gases in the atmosphere creating global warming as too much heat is trapped in
Evidence of human activities causing climate change
Global average temperature rise - measurements show an unusually rapid rise since the 1950s this correlates with rising CO2
Sea level rise - caused by melting ice, and thermal expansion (water expanding as it warms)
Declining arctic ice - each year more arctic ice melts in the summer
Human causes of climate change
Energy: burning fossil fuels (coal, oil, natural gas) releases CO2
Industry: rising incomes = more demand for manufactured goods
Transport: more people taking flights and driving cars burns more fuel
Agriculture: Intensive farming of cattle and rice creates methane
Consequences of climate change
Sea level rise could flood low lying islands, farmland and coastal settlements
Increased temperatures will melt sea ice and glaciers/increase droughts
Extreme weather - more tropical cyclones/heat waves/ flooding from intense rainfall
Predictions about climate change
Uncertainty around different variables (e.g. will human greenhouse gases continue rising) mean that projections of climate change impacts show a range of possible scenarios
Tropical Cyclones
2 case studies
Tropical cyclone
Large scale, rotating storms that form over the ocean in tropical areas - Southern hemisphere = spin clockwise , Northern hemisphere = spin anti clockwise
How do tropical cyclones form
Warm oceans heat the air above them, causing it to rise and creating extreme low pressure
Surrounding air rushes into the low pressure area, creating high winds
The warm rising air contains water vapour evaporated from the ocean this condenses into cumulonimbus (storm) clouds, bringing heavy rain
The Coriolis effect causes the wind and storm clouds to spin around a central point - the eye of the storm here cool air is sinking (high pressure) so it is cloudless and clear
Source regions
The area in which a tropical cyclone forms
What conditions are needed for cyclones to form
Warm seawater - water must be over 26.5℃ and 10-12km deep to provide the heat energy needed for tropical storms
Location - Tropical storms between 5-20° N and S of the equator (but not at the equator itself because there is not enough coriolis effect there)
Low wind shear - if winds at different heights are blowing at different speeds/directions they will pull the stoms apart
Cyclone seasons
Tropical cyclones form in late summer/autumn when oceans have warmed up
What hazards to tropical cyclones bring
Strong winds
Storm surges
Intense rainfall
Landslides
Strong winds
winds up to 160 miles an hour can take down power lines, trees and buildings, destroying settlements and killing/injuring people
Storm surges
Low pressure cyclones cause the ocean to expand as less air is pressing down on it this causes an extremely high tide that can flood coastlines
Intense rainfall
Tropical storms bring incredibly intense rainfall that can flood settlements and crops
Landslides
Land saturated by rainfall can give way, endangering property and lives.
Track
The pathway that a cyclone follows, driven by the patter of global wind circulation
Dissipation
When a cyclone moves over land or colder ocean it loses power as it no longer in contact with its heat source (warm seawater)
Saffir Simpson scale
Scale from 1-5 used to classify the power of a tropical cyclone, based on wind speed
Why are some countries more vulnerable to tropical storm?
Socio-economic factors
Physical factors
Socio-economic factors
Housing and infrastructure in developing countries tends to be weaker and more easily damaged
Developing countries may have less funding for forecasting and early warning systems
Populations with more very young or old people are more vulnerable as these age groups cannot evacuate as fast
Physical factors
Low-lying coastlines and islands are more vulnerable to flooding by storm surges
How can countries prepare for and respond to tropical cyclones?
Weather forecasting
Early warning systems
Evacuation strategies
Storm surge defences
Weather forecasting
Satellite technology can detect and monitor tropical storms. Computer models can combine data from satellites, weather stations, and aeroplanes to predict the path that a storm will take.
Early warning systems
Vulnerable populations can be alerted to approaching storms via radio, text and TV and encouraged to prepare (e.g. reinforce buildings and prepare emergency kits)
Evacuation strategies
Higher income countries with good roads and widespread car ownership can evacuate people quickly away from the coast.
In developing countries people people can still be evacuated locally to storm shelters (raised, concrete buildings)
Storm surge defences
Coastal embankments and sea walls can be built to guard against flooding from storm surges
Case studies
Typhoon Haiyan, 2013
The Philippines
Developing country: HDI: 0.71
Hurricane Katrina, 2005
USA
Developed country: HDI 0.92
Haiyan power
Category 5 tropical storm (one of the most powerful ever recorded)
195mph winds
Originated in the NW Pacific Ocean
Waves of up to 7m in height
Katrina power
Category 5 tropical storm
175 mph winds
Storm originated over the atlantic and made landfall over Louisiana and Florida
Caused storm surges of over 6m
Haiyan impacts
7000 people killed
Caused $5.8 billion of damage
1.9 million made homeless
90% of Tacloban (Philipines capital city) was flattened
71,000 hectares of farmland was affected.
Katrina impacts
1,800 people killed
Caused $125 billion worth of damage (the costliest storm ever recorded)
80% of the city of New Orleans was flooded.
Haiyan planning + preparation
The Philippines is a fairly poor part of the world with fewer resources for prediction, planning and protection.
They had evacuation shelters but many were not built high enough to withstand the 7m storm surges.
PAGASA, the Philippines' meteorological agency saved many lives by broadcasting warnings 2 days before Typhoon Haiyan hit. This lead to the evacuation of approximately 750,000 residents.
Katrina planning + preparation
Although the state made an evacuation order, many of the poorest people remained in New Orleans because they either wanted to protect their property or could not afford to leave
More than half of New Orleans lies below sea level and is protected from the Mississippi river by levees. However these did not withstand the storm surges and water flooded the city.
Haiyan response
The Philippines formally declared 'A State of National Calamity' and asked for international help, one day after Typhoon Haiyan hit the country.
The Tacloban city government was devastated, with only 70 people at work immediately after the disaster. Many were killed, injured or simply too traumatised to work.
The United Nations launched an international aid appeal for £480 million to finance the humanitarian relief effort
Katrina response
The US Government was heavily criticised for its handling of the disaster. Despite many people being evacuated, it was a very slow process. The poorest and most vulnerable were left behind.
The Superdome stadium was set up as a centre for people who could not escape the storm. However there was a shortage of food & the conditions were unhygienic.
Looting occurred throughout the city. The National Guard was mobilised to restore law and order.
The government provided $50 billion in aid.
Tectonic hazards
2 case studies
Crust
The rocky surface of the earth (also known as the lithosphere)
Earth’s crust is cool and solid. It is split into tectonic plates that move at 2-5 cm per year
Continental crust
Forms the land. Made mostly of granite. (30-50km) thick.
Oceanic crust
Forms the seabed. Much thinner (6-8km) and denser. Made of basalt.
Astenosphere
Partially molten, uppermost layer of the mantle - upon which the lithosphere moves around.
Mantle
Mostly solid, made of peridotite rock.
Temperature is between 1000-4000℃
Outer core
Liquid because so hot
Composition: iron and nickel
Temperature: Outer core - 4000 -5000℃
Inner core
Solid because it is under so much pressure
Composition: iron and nickel
Temperature: Inner core reaches up to 5400 (as hot as the surface of the sun)
Radioactive decay
The reason that earth’s core is hot. Radioactive elements in earth’s core (e.g. uranium) decay and release huge amounts of heat.
Convection currents
The heat of the core causes earth’s mantle to move in circular movements, dragging tectonic plates along with it.
Conservative Boundary
When two continental plates move alongside each other - creating earthquakes. E.g. San Andreas fault, California
Convergent boundary
When oceanic + continental crust collides the denser oceanic crust is forced (subducted) under the continental plate. Huge pressure causes large volcanic eruptions & earthquakes.
E.g. Andres Mountains in Chile / Peru
Divergent boundary
Found under the ocean where two oceanic plates are moving apart. Underwater shield volcanoes create new oceanic crust
e.g. mid-Atlantic Ridge
Earthquake causes
As plates slide past each other or collide, friction along the fault (crack) between them causes them to stick. Tension builds up until the plates slip, releasing energy as seismic waves.
Focus
The point underground, between two plates, where the earthquake takes place. The nearer to the earth’s surface this is, the more devastating the earthquake can be.
Epicentre
The point on earth’s surface, directly above the focus.
Magnitude
The power of an earthquake.
Measured using the Richter scale, a logarithmic scale so each step up is 10 times more powerful than the last
Composite volcano
Explosive, violent volcanoes found on convergent boundaries. Lava is viscous (sticky) and doesn’t flow far before it solidifies, so the volcano builds into a cone shape
Shield volcano
Volcanoes with gently sloping sides. Lava is runny, so volcanoes are less explosive.
Found on divergent boundaries
Tsunami
Giant waves are usually caused by an underwater earthquake displacing water and creating a fast-moving wave that travels across the sea. When the wave reaches shallow water near the coast it is pushed up and becomes taller.
Primary impacts
Instant impacts, caused directly by the shaking of the ground
E.g. buildings collapsing, railway lines and roads buckling, deaths from falling rubble
Secondary impacts
Impacts that happen later, as a result of the secondary impacts
E.g. fires from fallen power lines, disease outbreaks, homlessness, tsunamis, looting
Prediction
Trying to foresee when a hazardous event might hit a country
Earthquake prediction methods
Methods of predicting earthquakes are still very limited and unreliable:
1/ Use a seismometer to monitor vibrations in the earth’s crust. Increasing vibrations could signal an impending earthquake
2/ Monitoring radon gas escaping from earth’s crust. An increase could indicate an earthquake
Volcano prediction methods
Volcanic eruptions are easier to predict by:
1/ Using thermal imaging to monitor increasing temperatures in the volcano
2/ Using a seismometer to monitor small earthquakes that occur as magma forces its way upwards through cracks
Planning and preparation
Taking action to reduce the impacts of any earthquakes that may hit
E.g. having trained & funded emergency services, running safety drills in schools and workplaces, building earthquake resistant buildings and tsunami shelters
Earthquake resistant buildings
In developed countries, ‘base isolation’ and steel cross bracing stops buildings from swaying
In poorer locations housing can still be made safer e.g. by using lightweight thatched roofs, and bamboo frames instead of brick / concrete
Seisometer
The instrument used to measure earthquakes and vibrations in the earth’s crust
Case studies
Haiti, 2010
Developing country
HDI: 0.49
Sendai bay, Japan, 2011
Developed country
HDI 0.91
Haiti causes
Conservative plate boundary (North American + Caribbean plate sliding past each other)
Magnitude 7 earthquake
Focus 10km deep / epicentre 25 km from Haiti’s capital city, Port-au-Prince
Sendai bay causes
Convergent plate boundary (Pacific plate is subducting under Eurasian plate)
Magnitude 9 earthquake
Focus was 30km deep /epicentre 70km from the coast
Earthquake triggered a deadly tsunami
Haiti primary impacts
Poorly built homes collapsed killing 316,000
Key infrastructure (e.g the port and roads) totally destroyed
Economic cost: $8 million
Senpai bay primary impacts
Collapsing buildings killed 1,500
Damaged roads, rail, power, water
Costliest disaster in history: $235 million of damage
Haiti secondary impacts
Clean water cut off and cholera outbreak killed 8,000
Loss of income - Haiti’s clothing factories which provide 60% of exports were damaged
1 million were made homeless
Senpai bay secondary impacts
Created a 40m high tsunami that killed 15,500 thousand people
Fukushima nuclear power was flooded and went into meltdown
Haiti prediction
There is no way of predicting earthquakes
Senpai bay prediction
No way of predicting earthquakes but the Pacific Tsunami warning centre gave people some time to evacuate from tsunami
Haiti planning and preparation
Not prepared at all:
poor quality, densely packed buildings made of heavy concrete blocks - none were earthquake resistant
did not have trained emergency services or infrastructure to cope.
Senpai bay planning and preparation
More prepared:
70% Earthquake resistant buildings in the area
Well-trained emergency services
Regular drills in public buildings in how to evacuate for tsunamis and protect oneself in a earthquake
Haiti short term response
Initially chaos and no one in charge - the port was destroyed so aid could not get in.
Senpai bay short term response
Rescue workers and military were mobilised immediately.
Haiti long term response
Relied on international aid e.g. the US and UN
Some buildings took 10 years to be replaced
Senpai bay long term response
Buildings were restored in 4 years
Development dynamics
1 case study
Level of development
How wealthy a country is, and how much progress it has made in health care, education, democracy etc
Note
Flashcard