Natural Hazards Flashcards
Name each layer of the Earth from centre outwards
Inner core; outer core; mantle; crust
How many tectonic plates are on Earth?
7
What are the two types of Earth’s crust and what are their properties?
Continental crust - older, lighter, permanent;
Oceanic crust - younger, heavier, destroyed and replaced
Name the four different plate boundaries
Destructive; constructive; collision; conservative
What happens at a destructive plate boundary?
Continental crust collides with oceanic crust. The heavier oceanic crust sinks into the mantle and melts through subduction. Pressure builds, creating earthquakes. A large volcano forms from the melted oceanic crust and mantle and there are violent eruptions.
What happens at a constructive plate boundary?
This only happens underwater when two oceanic crusts move apart. The plates separate, releasing a gentle volcano. The magma solidifies, creating more crust. Gentle earthquakes are also found here.
What happens at a collision plate boundary?
Two continental crusts collide, creating violent earthquakes. Both plates buckle upwards, creating mountains.
What happens at a conservative plate boundary
The plates slide past each other, all of the building up pressure creating earthquakes.
How do plates move?
Convection currents work as parts of the liquid mantle heat up near the core and rise. They then travel along the crust, dragging it along slightly, cooling as they go. When they cool down so much, they will fall and repeat the process.
What is the epicentre of an earthquake?
The point on the surface closest to the focus.
What is the focus of an earthquake?
The built up pressure where the earthquake originated.
What are seismic waves?
The earthquakes energy travelling outwards in waves.
What is the Mercalli Scale?
A 12 point scale that measures earthquakes by describing the DAMAGE that can be seen afterwards.
What is the Richter Scale?
A 12 point scale that describes the MAGNITUDE or POWER of the earthquake, measured by a seismometer. Note that the Richter Scale is logarithmic.
What magnitude reading on the Richter scale does it have to exceed for it to be classified as an earthquake?
5
Case study: Christchurch
When did it happen?
12:51pm, 22nd February, 2011
Case study: Christchurch
Where did it happen?
Christchurch, New Zealand
Case study: Christchurch
What was the magnitude of the earthquake?
6.3
Case study: Christchurch
How many people were killed and how many seriously injured?
185; 164
Case study: Christchurch
What is liquefaction?
When the earthquakes vibrations cause underground water to be brought to the surface, turning the ground to thick, muddy slush.
Case study: Christchurch
How many buildings were damaged?
About 100,000, leaving over 10,000 homeless
Case study: Christchurch
What was the response like?
A plan of action was in place within 2 hours. Many countries came to help as well as many organisations bringing thousands of volunteers including farmers with machinery and students to clear up liquefaction.
Case study: Haiti
When did the earthquake take place?
Tuesday the 12th January 2010, at 16:53
Case study: Haiti
Where did the earthquake happen?
Haiti, the western third of the Caribbean island of Hispaniola in North America between the Caribbean Sea and the North Atlantic Ocean
Case study: Haiti
How big was the earthquake on the Richter Scale?
7.0
Case study: Haiti
How many were killed?
316,000
Case study: Haiti
How many homes were destroyed leaving how many homeless?
280,000, leaving 1 million homeless
Case study: Haiti
How many people lost jobs?
1 in 5
Case study: Haiti
What made the earthquake so devastating?
- focus only 5 miles below surface
- epicentre only 16 miles west
- 7 on Richter Scale
- Very poor country
Why do earthquakes affect LICs worse than HICs
- HICs have better support than other countries for a better response
- LICs have are poorer, so have weaker buildings
- LICs have generally worse healthcare, meaning injuries would more likely lead to death.
- LICs are poorer so are able to clear up the damage less easily, meaning impacts are more long term
What are the 3 Ps for managing earthquakes?
Predict, Prepare, Protect
How could we predict earthquakes?
- observing animal behaviour, as seemingly some animals can detect incoming earthquakes
- using seismographs to pick up minor tremors before the main event
- tiltmeters which check for any movement in the rocks
What are the features of an earthquake-proof building in a developed country?
- foundations sunk into bedrock, avoiding clay
- rubber shock absorbers to absorb tremors
- fire resistant building materials
- automatic window shutters to prevent falling glass
- ‘bird cage’ interlocking steel frame
- steel frames that can sway during movement
- computer controlled weights on roof to reduce movement
- roads to provide quick access for emergency services
- open areas where people can assemble if evacuated
What are the features of an earthquake-proof building in a developing country?
- cross-braced wood or bamboo frame
- lightweight thatch roof
- concrete ring tying the walls to the foundations
- simple steel rod foundations
- walls made of mud and straw packed between wooden slats
How can you prepare for an earthquake?
- identify potential hazards in your home and fix them
- create a disaster preparedness plan
- prepare disaster supply kits
- identify your buildings potential weaknesses and fix them
- protect yourself during earthquake shaking: drop, cover, hold on
What are the reasons for living near a volcano?
- fertile land
- surplus, free, clean energy
- tourism income
- mineral wealth (diamonds, gold, sulphur)
- may be unlikely to erupt
- no where else to live
What are the reasons against living near a volcano?
- if it erupts, your life will be destroyed: crops and livestock, family (and you) would die form the pyroclastic flow, toxic gasses, lava flow and ash rain
What creates low air pressure?
When air gets warm, it rises. Clouds form.
What creates high air pressure?
When air cools, it sinks. Mostly, skies are clear.
What are the names of the three cells, from nearest to the poles to furthest?
The Polar cell,
The Ferrel cell,
The Hadley cell.
What temperature does water have to be above for a tropical storm to form?
26.5ºc
What are the key parts of a tropical storm?
The eye: at the centre of the tropical storm, there is high air pressure as air sinks, skies are clear, there is no wind
The eye wall: maximum wind speeds of up to 225mph
Spiral rain bands: winds start from 70mph with driving rain
The strong upwards movement of air draws water vapour up from the warm ocean surface.
What scale measures tropical storm power?
The Saffir-Simpson Scale:
[1] 74 - 95mph
[2] 96 - 110mph
[3] 111 - 130mph
[4] 131 - 155mph
[5] >155mph
Case study: Typhoon Haiyan
When was the typhoon?
Struck land first at 4:40am, on November the 8th 2013
Case study: Typhoon Haiyan
How many people died?
Over 8,000
Case study: Typhoon Haiyan
What category of tropical storm was the typhoon?
It started off as a category 5 as it reached the Philippines, but by the time it reached Vietnam it had lost power, becoming a category 2 storm.
Case study: Typhoon Haiyan
How many homes and fishing boats were destroyed?
40,000 homes and 30,000 fishing boats
Case study: Typhoon Haiyan
How tall was the storm surge?
5m
Case study: ‘The Beast from the East’
When did this weather event occur?
2018
Case study: ‘The Beast from the East’
How many died?
18 officially, estimated 2000-3000 indirectly
Case study: ‘The Beast from the East’
What were the effects?
- 50cm snow in some places, but wind caused snow drifts up to 20 feet deep
- First ever red snow warning in the uk
- People stranded up to 7 days in rural areas
- storm Emma caused 90mph winds
- road accidents
- M62 completely cut off
What evidence is there for climate change?
- Ice cores - trapped air can reveal the atmospheric make up of many thousands of years ago
- Melting glaciers and sea ice - the Menden Hall glacier in Alaska has retreated over 1.75 miles since 1929, and has halved in size since 1984
- Rising sea levels - the sea levels have risen over 8 inches since 1880, and the increase is accelerating
- Dendrochronology - by looking at tree rings, you can see that the narrower the ring, the less growth there was and therefore the drier the environment was,
How has Earth’s climate always changed?
The Earth regularly goes through cycles of warming, temperature rising quickly into an interglacial period, before dropping slowly into a glacial period.
What are the four main greenhouse gasses?
Carbon dioxide, methane, nitrous oxide and water vapour
What are the likely effects of global warming on Earth?
- Stronger tropical storms
- Higher global temperatures affecting food production and water supply
- Environmental impacts, such as desertification
- Wildlife at risk as habitats and ecosystems change
- Rising sea levels threaten low-lying coastal areas
- Economic impacts, such as lower crop yields and damage to infrastructure
- Increased risk of natural hazards, such as droughts and floods
- More heat-related illnesses and diseases, such as malaria
What mitigation strategies are there to do with climate change?
- Carbon capture
- Alternative energy
- Afforestation
- International agreements
What adaptation strategies are there to do with climate change?
- Change in agricultural systems (drought-resistant crops, new irrigation systems, new cropping patterns introduced)
- Managing water supply
- Reducing risk from rising sea levels
What were some secondary effects of Typhoon Haiyan?
- Flooding and heavy rain caused landslides, which, with other debris, blocked roads and delayed aid.
- 6 million lost their source of income.
- Looting and violence broke out in the chaos.
What city was worse affected by Typhoon Haiyan?
Tacloban:
- It was hit by the 5m storm surge, channeled by the shape of the land, which destroyed 90% of the city, which had a population of over 200,000.
What were the immediate responses to Haiyan?
- Philippines Red Cross supplied over 1.1 million with clean water.
- Canada and the USA deployed military aircrafts to assist with search and rescue of survivors. They also brought aid supplies.
- France, Belgium and Israel set up field hospitals to help the injured.
What were the long-term responses to Haiyan?
- UNICEF and the WHO vaccinated thousands against diseases. This was set up to ensure the diseases did not spread through temporary shelters.
- A ‘build back better’ strategy pledged that 205,000 homes would be built. However, by 2016, only 1% of that was achieved.
- Typhoon shelters were built.
- Financial aid was sent in by countries such as the UK, Japan, Australia and the USA.
