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Geography (s2) > The Unstable Earth > Flashcards

The Unstable Earth Flashcards

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1
Q

What is a natural hazard

A

It is a naturally occurring process or events which has the potential to cause loss of life or damages to properties

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2
Q

How many layers are there to form Earth? How are they arranged?

A

There are three layers that form Earth: crust, mantle and core. They are arranged according to the density. The layer with lighter and less dense minerals lie on the top.

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3
Q

What are the characteristics of the crust?

A

It has the thinnest layer, which is 6-70km. Its density is low. It’s compositions include silica, aluminium, and magnesium. The state of the crust is solid, and it forms the ocean and land floors.

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4
Q

What are the characteristics of the mantle?

A

Its thickness is 2900km, and its density is high. Its composition includes aluminium and iron. The state of the mantle is semi-molten. It is made up by magma.

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5
Q

What is the characteristics of the core?

A

The core has the thickest thickness among all, which is 3470 km. Its density is the highest. Its compositions include iron and nickel. Its outer state is liquid while its inner state is solid. It is the thickest layer on Earth and it is made up of heavy metals.

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6
Q

What are the characteristics of all the layer on Earth?

A

The crust has the thinnest layer, which is 6-70km. Its density is low. It’s compositions include silica, aluminium, and magnesium. The state of the crust is solid, and it forms the ocean and land floors.

The mantle’s thickness is 2900km, and its density is high. Its composition includes aluminium and iron. The state of the mantle is semi-molten. It is made up by magma.

The core has the thickest thickness among all, which is 3470 km. Its density is the highest. Its compositions include iron and nickel. Its outer state is liquid while its inner state is solid. It is the thickest layer on Earth and it is made up of heavy metals.

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7
Q

Describe the global distribution pattern of tectonic hazards

A

The hazards are located along plate boundaries, but 10% aren’t.

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8
Q

Name all the plate names

A

African Plate, Eurasian Plate, Indo-Australian Plate, Pacific Plate, North American Plate, South American Plate, Nazca Plate
Cocos Plate, Scotia Plate, Philippine Plate, Okhotsk Plate, Juan de Fuca Plate, Caribbean Plate, Arabian Plate

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9
Q

What is the characteristics of continental crust?

A

Continental crust made up the continents, and it is thick and light. It is rich in silica and aluminium.

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10
Q

What are the characteristics of oceanic crust?

A

It makes up the ocean. It is thinner, denser, and heavier than the continental crust. It is rich in silica and magnesium.

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11
Q

How do the plates move?

A

Since the Oceanic crust is denser than the continental crust, it will always go beneath the continental crust, creating a trench, which is the deepest part of the ocean. The heat in the mantle creates powerful convection current. They drag the plates to move in different directions

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12
Q

What are the three different plate boundaries?

A

Destructive plate boundary ➡️⬅️
Constructive plate boundary ⬅️➡️
Conservative plate boundary ⬇️⬆️

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13
Q

What tectonic hazard might occur at constructive plate boundary??

A

Volcanic eruption and earthquake

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14
Q

What are the causes that constructive plate boundaries do?

A

Since the plate boundaries are moving away from each other, it will create a volcanic vent. Magma from the mantle will then rises up, and it will construct new lands.

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15
Q

What tectonic hazard does destructive plate boundaries cause?

A

Volcanic eruption and earthquake

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16
Q

What are the causes of destructive plate boundaries?

A

Since the oceanic crust are going below the continental crust, it is destroying the crust since the crust will slowly reaching the magma, and causing it to melt.

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17
Q

What tectonic hazard does conservative plate boundaries cause?

A

Earthquake

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18
Q

What causes does conservative plate boundaries cause?

A

For conservation plate boundaries, since the plate are only moving past each other horizontally, it won’t construct or destroy anything.

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19
Q

What are the mantle’s uppermost part and the crust collectively known as?

A

Lithosphere

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20
Q

What is lithosphere?

A

Lithosphere is collectively known as the uppermost part of the mantle with the crust. It is not one whole piece of rigid rock but broken into pieces call plates.

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21
Q

Where does the plate lie and “float”?

A

On the upper part of the mantle, asthenosphere

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22
Q

What is an asthenosphere?

A

Asthenosphere is in a plastic state, and is where plate lies and float. This means that rocks can flow very slowly under high temperature and pressure.

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23
Q

How do we distinguish between primary and secondary impacts?

A

Primary impacts are the immediate and direct effects of an earthquake. Secondary impacts are the knock-on effects as a result of the primary impacts.

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24
Q

List all the possible primary effects

A

Building collapse
Railway track buckle
Roads, bridges destroyed
Landslide, or snow avalanches or tsunami
Shaking of the ground
Liquefaction
Water and electricity supplies damaged

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25
Q

List out all the possible secondary impacts

A

Outbreak of fire DUE TO ruptured gas lines
Railway tracks buckle
Road, bridges destroyed
Outbreak of diseases
Water and electricity supplies damaged
Agricultural loss DUE TO landslide or tsunami
Floods
Disruption of the delivery of emergency aid

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26
Q

What is an earthquake? (⭐️)

A

When the plates move along the plate boundaries, the rock experiences stress. Energy is built up and stored in the rock. When the stored energy exceeds the strength of the rock, the rock breaks. The stored energy is released, and this causes the sudden shaking of the ground called earthquake.

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27
Q

What are the two main earthquake zones?

A

Circum-Pacific Belt
Alpine-Himalayan Belt

28
Q

What is an epicentre

A

It’s the point on the Earth’s surface vertically above the focus

29
Q

What is the focus

A

It is the point where the crust suddenly fracture and release seismic waves

30
Q

What are the type of focuses

A
  1. Shallow focus (0-70 km underground)
  2. Medium Focus (70-300 km underground)
  3. Deep focus (Over 300 km underground)
31
Q

What is the formation of an earthquake at ____________?

A

Along the destructive/constructive/conservative plate boundaries, ___________ plate and ____________ plate (the plate names that the earthquake lies on) moves towards/away/along each other. Pressure builds up along the plate boundaries, energy is then built up and stored in the rock. When the stored energy exceeds the strength of the rock, the rock breaks. The stored energy is released. This causes the sudden shaking of the ground called earthquake.

32
Q

What kind of long term effect which are likely to result from an earthquake? (What types of effects do I have to write during the exam?)

A
  1. Social ~ human, injuries, loss of lives
  2. Economic ~ buildings, roads, reconstruction
  3. Environmental ~ nature, slope failure, liquefaction
33
Q

What is liquefaction?

A

It’s where soil with a high water content lose their mechanical strength when violently shaken during an earthquake and start to behave like a fluid.

34
Q

Preventive measures for earthquake

A
  1. Setting up monitoring and early warning systems:
    - alert people before an earthquake arrives to their location so they have enough time to evacuate
  2. Adopting careful land use planning:
    - just like avoiding development and building facilities with potential dangers in earthquake-prone areas (nuclear power plant / oil depots)
    - set up evacuation routes with adequate road signs to guide people to safe places as soon as possible
  3. Constructing earthquake-proof buildings and structures:
    - lessen down the risks of collapsion of buildings
  4. Educating people and have regular earthquake drills:
    - increase people’s awareness
    - reduce the rate of losses and injuries
35
Q

Medical measures for earthquakes

A
  1. Have well-trained rescue team:
    - can increase the number of survivors
  2. Provide temporary shelters, emergency and financial aids
    - shelters and emergency supplies of food increase the chance of survival after earthquakes
    - financial aid helps people rebuild their homes
36
Q

Why is the outer core liquid and the inner core solid?

A

As a person goes deeper in Earth, both temperature and pressure increases. Although the inner core is very hot, it is solid because it is experiencing very high pressure. The pressure in the outer core is not high enough to make it solid.

37
Q

Why do most earthquakes occur along plate boundaries

A

When the pressure in the plates exceeds the strength of the rock, the rock breaks and displaces. The land then shakes, causing earthquake to occur

38
Q

Which type of plate boundary produce more stronger earthquake?

A

Friction is greater at destructive and conservative plate boundaries, therefore, higher pressure is built up. As a result, earthquakes are stronger and more frequent there.

39
Q

How can we measure earthquakes?

A

We can measure it either by Richter scale or Modified Mercalli Scale

40
Q

What does the Richter Scale measure? How is it used to measure?

A

Richter Scale measure magnitude of the earthquake and the amount of energy release by an earthquake. And a seismograph is used.
The Richter Scale ranges from 1 to 9. 1 being an earthquake that human wouldn’t even notice to a 9 that means a 30 times more energy than 8. (Or 240 times stronger than 1)

41
Q

What does Modified Mercalli Scale measure? How is it measured?

A

Modified Mercalli Scale measures the intensity of an earthquake and the degree of damages the earthquake caused. It measures the earthquake by modified mercalli.
The degree of damage the earthquake caused, the scale rangers from I to XII

42
Q

which measure might be more accurate?

A

Richter scale. It is a scientific method, and it can detect very small earthquakes using seismic waves. Meanwhile, for Mercalli Scale, it’s subjective based on people’s opinions/perception, and damage seen.

43
Q

What is volcano?

A

Volcano is an opening in the Earth’s crust which allows hot molten materials erupting onto the land

44
Q

What are volcanic eruptions

A

Volcanic eruptions are processes by which extremely hot materials are ejected or emitted from an opening in the earth’s surface.

45
Q

Why do volcanic eruptions occur? (⭐️)

A

The heat in the mantle creates a powerful convection current, dragging the plates to move towards/away from each other. This leads to high pressure beneath the Earth’s surface. Magma and gases are pushed up through lines of weakness or vents, causing a volcanic eruption when it pushes all the way through the opening of the earth’s crust.

46
Q

How can we tell if a volcano will erupt soon?

A

We can know when
1. We start getting small earthquakes
2. Gas leaks from vent (sulphur dioxide)
3. Other volcanic activity (small eruptions)
4. Bulges can appear, which is caused by the build up of magma near the surface. This can also be detected with heat sensing satellites
5. Animals starts to act strangely.

But overall, predictions are rarely accurate.

47
Q

What are the three frequency of eruptions?

A
  1. Active volcanoes ~ will erupt at any time
  2. Dormant volcanoes ~ inactive for quite a long period of time
  3. Extinct volcanoes ~ all eruptions are presumed to have completely stopped
48
Q

What is vulnerability?

A

The extent to which a community, structures service or geographical area is likely to be damaged or disrupted by the impact of a disaster hazard

49
Q

What are some factors that concerns the affected area from volcanic eruption/earthquakes/tectonic hazards?

A
  1. Population density of the area: the higher the population density is, the more people exposed to the hazards, the more amount of risks of loss of live
  2. Level of economic development: more economic infrastructure means a greater amount of valuable property and structural networks destroyed
  3. The weather after the hazard occur: extreme weather such as a bitter cold and burning sun can raise the death toll in areas where shelter and shade are insufficient
  4. Relief of land: steep slopes create fast lava flows after volcanic erupt opens and more landslides after earthquakes
50
Q

How does the effects of earthquakes vary?

A

It varies according to the level of development of a country

51
Q

Difference between MEDCs and LEDCs

A

MEDCs has a higher economic loss than LEDCs
LEDCs has a higher casualties than MEDCs

52
Q

Why does less developed countries suffer more from tectonic hazards?

A

Firstly, the popularity density of LEDCs is higher than MEDCs. Their economic developments, education and awareness are lower than the rate of MEDCs. LEDCs’ building materials and codes are much weaker than the ones in MEDCs. And at last, the government planning, monitoring and emergency planning of LEDCs have less plannings than MEDCs.

53
Q

Why is the economic development in LEDCs much lower than MEDCs?

A

For LEDCs, they lack a big amount of money, causing them to have difficulties to conduct research, develop warning systems and improve reduce equipments. This results in no warning before any tectonic hazard occurs, and governments can’t afford rescue work.

54
Q

Why is the strength of buildings in LEDCs weaker than the ones in MEDCs?

A

The buildings built in LEDCs are often built of wood, bricks or stones, while the buildings built in MEDCs are often built of concrete and steel.

55
Q

Why are people in LEDCs have less awareness for hazards?

A

People are less prepared for hazards since they have strong traditional values and are ignorant. They also receive little education.

56
Q

What is happening in the government efficiency in LEDCs?

A

Corruption is happening, and it is common is LEDCs areas. Many resources for relief may not reach the refugees.

57
Q

What are the factors that concerns the tectonic hazards?

A
  • the path through which the hazard “travels”
  • time of the occurrence
  • magnitude
  • duration
  • distance from the source of destruction (epicentre)
58
Q

What are the factors that concern the affected area?

A
  • weather after the hazard occurs
  • relief of land
  • population density of the area
  • level of economic development
59
Q

what does the population density results in LEDCs suffering more than MEDCs during tectonic hazards?

A

The population density in LEDCs are usually higher, creating a much higher death toll when the hazards strike.

60
Q

what is a rational thinking?

A

A rational person will consider whether possible gains are greater than possible losses, for both staying and leaving an area that have a greater chance of experiencing a tectonic hazard.

61
Q

The decisions of stay or leave depends on one’s subjective but careful evaluation of a few things. List them out

A
  • the perceived risk of hazards happening in the area
  • the possible gains from the opportunities offered by tectonic processes
  • the possible gains if one leaves the hazard-prone area
  • the possible losses if one leaves the hazard-prone area
62
Q

what are the three main topics of managing the risks of earthquakes?

A

Predict: use different methods to forecast when an earthquake might happen so people can be warned

Protect: make sure buildings are flexible and strong so they don’t fall down during an earthquake

Prepare: make sure people know what to do in an earthquake and that emergency service practice what to do

63
Q

Why do people still live in hazard prone areas? (talk about the environment, social, economic)

A
  1. supply of natural resources: there are rich natural resources such as geothermal power which can generate electricity. Some places have beautiful landscapes such as geysers and hot spring which are favourable for the development of tourism
  2. good climate and flat land: some typhoon-prone areas have mild climate and plenty of rainfall which is good for agriculture
  3. high level of economic development: some earthquake-prone areas are well-developed. People enjoy a high living standard are there are many job opportunities
  4. underestimate the risks of natural hazards: some people believe that disastrous hazards are unpredictable. they believe their governments are well prepared and can respond immediately and effectively to reduce the impacts
  5. not able or not willing to move: some people do not have capital to move to a safe place. Secondly, they do not want to give up their jobs. Thirdly, they have string social ties with family members at home. Lastly, they are afraid that they can’t adapt to the new environment.
64
Q

what causes a greater loss to a place during an earthquake? (base on only the place, but not the earthquake’s information)

A
  1. more developed area means it is densely populated
  2. contains a lot of high-rise buildings
  3. more economic activities found
65
Q

How does the epicentre of an earthquake influence the impact of the earthquake?

A

The nearer the place is to the epicentre, the higher the intensity of the earthquake will be. If the epicentre is far from the place, hopefully the seismic wave passed to the place will be less intensive

Geography (s2) (3 decks)

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