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Geography > P1 - Tectonics > Flashcards

P1 - Tectonics Flashcards

1
Q

What is the inner core?

A
  • the hotest part of the earth
  • it’s temp ranges from 4500-6000 degrees celcius
  • it is solid and mostly consists of iron
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2
Q

What is the outer core?

A
  • semi-molten and mostly consists of liquid iron and nickle
  • it surrounds the inner core
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3
Q

What is the mantle?

A
  • it includes the asthenosphere- semi-molten on which tectonic float
  • it surrounds the core and is the widest layer
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4
Q

What is the crust?

A
  • forms the outer shell of the earth
  • two types: oceanic and continental
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5
Q

What are the four processes that make plates move?

A
  1. Convection
  2. Slab pull & ridge push
  3. Subduction
  4. Sea floor spreading
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6
Q

What are convection currents?

A

Magma rises as it has been heated by the core, it is then blocked by the crust so then begins to fall back down to the core as it cools
Because the magma hits the crust it will overtime cause the plates to pull apart

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7
Q

NEED TO DO SLAB PULL & RIDGE PUSH, SUBDUCTION AND SEA FLOOR SPREADING

A
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8
Q

Destructive plate boundary:
1. What happens at this boundary?
2. What hazards can be found?
3. Example

A
  1. Oceanic plate subducts underneath the less dense continental plate. The oceanic plate melts as it reaches the subduction zone and can force its way to the surface as magma
  2. Highly destructive earthquakes, volcanoes, tsunamis
  3. Nazca Plate, South America
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9
Q

Constructive plate boundary:
1. What happens at this boundary?
2. What hazards can be found?
3. Example

A
  1. Two plates move apart from each other. Magma wells to the surface to fill the gaps left by the plates, forming a new crust
  2. destructive earthquakes, volcanoes
  3. Mid-Atlantic Ridge, Iceland
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10
Q

Collisional plate boundary:
1. What happens at this boundary?
2. What hazards can be found?
3. Example

A
  1. Two continental plates move towards each other. Fold mountains are created
  2. Destructive earthquakes
  3. Himalaya Mountain Range, Nepal
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11
Q

Conservative plate boundary:
1. What happens at this boundary?
2. What hazards can be found?
3. Example

A
  1. Two plates move past each other in opposite directions or in the same direction at different speeds
  2. Highly destructive earthquakes
  3. San Andreas Fault, California, USA
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12
Q

Intraplate earthquakes

A

Caused by stresses within a plate. Since plates move over a spheric surface, zones of weakness are creates. Earthquakes can happen in these zones

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13
Q

Hot spots

A

A plum of magma escapes the outer core and burns through all the layers of the earth. This creates a volcano. When the plates move this creates many volcanoes next to eachother

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14
Q

Who created the law of superposition and what is it?

A

Nicolaus Steno

Each layer of rock is older than the layer above it

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15
Q

Who came up with the supercontinent, what is it, what was it called and what did they believe was the cause of the plates moving apart?

A

Alfred Wegener

Once all the continents were joined together- called Pangea

The plates moved apart due to a phenomenon called ‘contenental displacement’

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16
Q

what is Paleomagnetism, what does it evidence and where can this been seen

A

Magma contains a lot of Iron

Iron particles point to magnetic north
every 300,000 years, Magnetic north flips to the opposite direction (magnetic south)

This means that newly formed magma contains iron pointing in the opposite direction

This gives evidence for sea floor spreading and can be seen along the mid Atlantic ridge

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17
Q

What is the main principle of the wilson cycle

A

Some oceans get bigger and others shrink as ridge push is stronger than slab pull

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18
Q

What are the 5 steps of the wilson cycle

A
  • A continent rifts when it breaks up
  • As it continues, an ocean opens, margins cool and sediment accumulates
  • convergence begins (Subduction); an oceanic plate subducts, creating a volcanic and active margin
  • Terrace accretion occurs (rock from two different plates stick together)
  • as the two continents collide- mountains form and the ocean is closed up
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19
Q

How do conservative plate boundaries form earthquakes?

A

Friction builds as the plates move past each other
the plates become stuck, either because there is a fragment of rock in the way or because of the shape of boundary; this is called a locked boundary
eventually, the pressure that has built up due to this overcomes the strength of the fault and one plate slips past another
seismic waves radiate out from the point of movement, the focus to the epicentre

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20
Q

what is the benioff zone

A

an area of seismic activity corresponding with the slab being thrust downwards in a subduction zone; different speeds and movement of rock at this point produce numerous earthquakes- theoretically, this determines the magnitude of the earthquake

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21
Q

Primary waves

A
  • caused by compressions
    -quick- 8km/s
  • lowest amplitude
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22
Q

Secondary waves

A
  • highest frequency
  • faster than L waves but slower than p waves (4km/s)
  • (up and down)
  • highest frequency
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23
Q

Love waves

A

-highest amplitude
- most destructive
- side to side
-(1.4 km/s)

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24
Q

What is soil liquifaction and why does it happen

A
  • water saturated material can temporarily lose normal strength and behave like a liquid under the pressure of strong shaking
  • this is because the earthquake can increase water pressure to the point where soil particles move easily, especially in sand and silt
  • often occurs in land adjacent to rivers
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25
Q

what are the impacts of soil liquifaction and what is an example of where soil liquifaction has happened

A

-damage to roads and bridges as well as telecommunication and other services
- this disrupts delivery of aid and causes large rebuild costs
- christchurch 2011- cars buried

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26
Q

What is a landslide

A
  • Slopes weaken and fall
  • occurs in mountainous areas
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27
Q

give an example of a landslide

A

nepal 2015- entire village buried

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28
Q

What plates do tsunamis occur at

A
  • destructive; plates pushed together and then then older, denser plate suddenly slips under
  • lots of pressure released and a tsunami is formed
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29
Q

name the key features of a tsunami (7)

A

-very long wavelength
- can travel thousands of kms
- approaching the shore, the tsunami speed diminishes
- moves in an eliptical motion
- water withdraws at the coast before the wave arrives
wave amplitudes increase as it approaches the shore to as much as 100ft. this is known as wave shoaling
-waves move fast at roghly 800km/hr

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30
Q

what is wave shoaling

A

the process of the waves losing volume but gaining height as they get closer to shore

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31
Q

what factors can increase the size of a tsunami wave

A
  • shallow water depth near to coast
  • steep gradient change of sea bed towards coastline
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32
Q

what factors can increase the speed of a tsunami wave

A
  • no environmental buffer (eg. no mangrove swamps)
  • deep water depth near to coast line
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33
Q

what factors increase the strength of a tsunami wave

A
  • short distance travelled
  • large amount of water so large volume displaced
  • boundary locked for a long time ( can lead to a mega thrust earthquake causing a strong tsunami)
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34
Q

CASE STUDY of a tsunami

A

Boxing Day tsunami 2004

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35
Q

Boxing Day tsunami (2004) key facts

A

Also known as Ocean Tsunami

Largest tectonic disaster in modern history with 290,000 dead/missing

1 in 100 year event

Caused by EQ which was 9.1 on the Richter scale

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36
Q

What is soil liquefaction?

A

Water saturated sandy layers of the earth act like liquids due to the pressure created by EQ’s

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37
Q

Social impacts of 2004 Boxing Day tsunami

A

120,000 tourist workers in Thailand lost jobs

Schools and hospitals damaged so several closed

1.7mil left homeless

Disease spread due to sewage mixing with sea and freshwater

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38
Q

Economic impacts of 2004 Boxing Day tsunami

A

Ports damaged = affected trade

Tourism industry in Thailand lost $25mil per month

Infrastructure destroyed

60% fishing fleets destroyed in Sri Lanka

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39
Q

Environmental impacts of 2004 Boxing Day tsunami

A

Damaged ecosystems —> EG. coral reefs, coastal wetlands

Most vegetation and topsoil was removed up to 800metres inland

8mil litres of oil escaped from oil plants in Indonesia

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40
Q

Primary hazards of volcanoes: lava flows

A

Extensive areas of solidified lava, which can extend several kilometres from volcanic vents if the lava is basaltic and low viscosity. It can flow at up to 40 km/h.

Occurs at:
subduction zone volcano (composite)
hot-spot volcano (shield type)

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41
Q

Primary hazards of volcanoes: pyroclastic flow

A

Very large, dense clouds of hot ash and gas at temperatures of up to 600’C. They can flow down the flanks of volcanoes and devastate large areas.

Occurs at:
Subduction zone volcano (composite)

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42
Q

Primary hazards of volcanoes: Ash falls

A

Ash particles, and larger tephra particles, can blanket large areas in ash, killing vegetation, collapsing buildings and poisoning water sources.
Occurs at:
Constructive plate margin volcanoes (cinder cone, fissure eruption)
Subduction zone volcano (composite)

43
Q

Primary hazards of volcanoes: gas eruptions

A

The eruption of carbon dioxide and sulphur dioxide, which can poison people and animals in extreme cases.

Occurs at:
Subduction zone volcanoes (composite)
Hot-spot volcano (shield)

44
Q

Secondary hazards from volcanoes: lahars

A

Volcanic mudflows, which occur when rainfall mobilises volcanic ash. They travel at high speed down river systems and cause major destruction.

Occurs at:
Subduction zone volcanoes (composite)

45
Q

Secondary hazards from volcanoes: jokulhlaups

A

Devastating floods caused when volcanoes erupt beneath glaciers and ice caps, creating huge volumes of meltwater. They are common in Iceland.

Occurs at:
Constructive plate margin volcanoes (cinder cone, fissure eruption)

46
Q

CASE STUDY: Eyjafjallajokull key facts

A

Volcanic eruption

2010

Iceland

100,000Cancelled flights in worldwide for weeks (due to spreading of gas and ash cloud - cause damage to plane engines)

10mil stranded passengers

$1.7B loss in airlines revenue

$5B loss European economy

Impacts felt as far as Kenya, where export of perishable goods was impacted due to lack of transport —> $1.3mil in revenue was lost per day

47
Q

CASE STUDY: Montserrat key facts

A

Soufriere Hills Volcano in south of Island on Caribbean Sea erupted

Huge ash clouds over next 5 years

7000 residents moved to other countries

The capital - Plymouth- was destroyed which had all of the islands services

2/3 houses and 3/4 infrastructure destroyed

Unemployment rose as tourism industry collapsed

Top heavy pop. as young ppl left due to lack of econ opportunities on island

48
Q

How are volcanic eruptions measured?

A

Volcanic Explosivity Index (VEI):
Compares and describes the magnitude of volcanic eruptions
0-8 scale (logarithmic)
Measures - height of material ejected, duration of eruption

49
Q

How are eruptions predicted?

A

Change in shape - magma builds pressure as it rises causing volcano to swell and change in shape

Gas - close to eruption, small of egg (sign that sulphur is being emitted from volcano - showing magma is near to surface)

Temperature (temp) - water and rock can be tested for temp which can be an indication that magma is nearer to surface than normal

50
Q

How tectonic hazards are measured: Mercalli scale

A

Roman numerals

Composed of increasing scales of intensity ranges from shaking to destruction

51
Q

How tectonic hazards are measured: Richter scale

A

Measures magnitude of EQ

Logarithm of the amplitude waves recorded by seismographs

Expressed in whole numbers and decimal fractions

52
Q

How tectonic hazards are measured: Moment magnitude scale (MMS)

A

Measures size of EQ in terms of energy released

Calculated from:
- amount of slip on the fault
- area affected
- an earth rigidly factor

53
Q

What is Deggs model?

A

Venn diagram illustrating the interception of both the hazardous geophysical event and vulnerable pop.

54
Q

Define resilience

A

Ability to protect lives, livelihoods and infrastructure from destruction and to restore areas after a natural hazard has occurred

55
Q

Define vulnerability

A

Ability to anticipate, cope with, resist and recover from natural hazards

56
Q

Risk equation

A

Hazard x vulnerability
——————————
Capacity to cope

57
Q

Define risk

A

Exposure of ppl to a hazardous event

More specifically:
Probability of hazard occurring that leads to loss of lives/livelihoods

58
Q

Give 5 examples of risks

A

Ageing population
Low lvls of development
Unpredictability
Magnitude
Adaptation

59
Q

What is the basis of the PAR model?

A

Root causes —> dynamic pressures —> unsafe conditions

60
Q

Examples of root causes

A

Limited access to resources, political/economic systems

61
Q

Examples of dynamic pressures

A

Lack of appropriate skills - eg. Training, local investment, press freedom

62
Q

Examples of unsafe conditions

A

Fragile physical environment
Fragile local economy
Vulnerable society

63
Q

Earthquakes that happen in _____ are often _____ costly as the infrastructure is more _____ and the loss of business is more _____

A

Rich places
More
Developed
Significant

64
Q

Social impacts of tectonic hazards

A

Deaths
Stress on healthcare services
Spread of disease
Homelessness
Water/electricity lost
Hindered education

65
Q

Economic impacts of tectonic hazards

A

Damage to transport (can’t get to work) (has to be repaired)
Loss of jobs (eg in tourism)
Infrastructure damage
Tourism decrease
Damage to agricultural industry

66
Q

Comparison of Haiti EQ (2010) and Alaska EQ (1964)

A

(H) Haiti:
7.0 Mw
x1 Mercalli
160,000 deaths
$8B damage

(A) Alaska:
9.2Mw
x1 Mercalli
131 deaths
$311M damage

= less deaths in A even though A was more destructive. A was less expensive to repair as less damage due to preparation

67
Q

List 7 human dynamic factors

A

Education - reduces vulnerability

Housing - poor housing results in collapsing and deaths

Healthcare - good emergency services means more lives saved

Income opportunities - higher income = above = better standard

Levels of development

Quality of governance

Demographics

68
Q

Why is the collection of disaster data often incomplete or inaccurate?

A

Immediate focus is response not data collection
Hard to get data in remote areas so estimates can be inaccurate
May be subject to political bias

69
Q

What is a mega disaster?

A

Large scale

High impact

Low probability

International responses

Require effective management

Happen rarely

70
Q

CASE STUDY: Japan 2011 facts and stats

A

5% loss in overall GDP

Damage to Fukushima nuclear plant disabled power supply which caused radioactive releases

Toyota and Sony haltered their production

71
Q

Vulnerability in Philippines

A

1976, midland EQ, magnitude of 7.9, causing tsunamis, killing 8000

79% economic losses came from tropical storms

17% of economic losses came from flooding

72
Q

Challenges in the Philippines

A

Cant spend money on developing the country —> have to spend it on rebuilding

Climate means that annual tropical storms bring floods, landslides, lahars and volcanic eruptions

73
Q

Why is Morocco vulnerable? 🇲🇦

A

Dependant on agriculture, fishing and tourism —> if a natural disaster or devastation affects environment it could leave them with nothing

Water scarcity

Food insecurity

Shoreline erosion

Moroccan economy is very exposed to impacts of climate change

74
Q

Morocco facts and stats:

A

Pop: 10mil
UNDP human development index (HDI): 158th in world
GDP Per capita (per person): $1,179
Life expectancy: 62
Mean years in education: 5

75
Q

LIC example of an EQ: Haiti

A

Causes - sits amongst complex plate boundaries

Dynamic factors - pop of 9.8M affected, high infant mortality

Impacts - 60% of their capital destroyed, 70% buildings collapsed, $8B damage, 230,000 deaths

76
Q

HIC EQ example: New Zealand

A

Causes - 6.3 Richter scale, epicentre less than 6km away

Dynamic factors - developed, $10B set aside

Impacts - $20B damage, 6000 injured, 185 deaths

77
Q

LIC example of EQ

A

2004 Indian Ocean Boxing Day tsunami

78
Q

HIC tsunami example: 2011 Tohoku

A

Causes - large EQ hit Japan, triggering biggest tsunami in Japan’s history, 9.0 Richter scale, after just 22mins the first town was hit

Dynamic factors - strong infrastructure due to investment, good education (ppl told to evacuate and go to higher ground)

Impacts - 20,000 dead/missing, 60% =0.6 over 60 (at home, no tech —> no warning), nuclear power plant destroyed

79
Q

Predicting volcanoes: gas monitoring

A

High sulphur levels means magma is near surface

80
Q

Predicting tectonic hazards: seismometers

A

Monitoring the land to see if increase in seismic activity

81
Q

Predicting volcanoes: thermal imaging

A

Can detect heat around volcano - more heat = more magma near surface

82
Q

Predicting volcanoes: boreholes

A

Scientists can drill into volcano and test height of water level

83
Q

Why is forecasting important?

A

It can encourage governments to enforce better building regulations in areas of high stress or create improved evacuation procedures in areas of high risk

84
Q

Parks disaster response curve 1991

A

The Park model is also known as the disaster response curve. Its aim is to show the effects of a hazard on quality of life over a sequence of time

85
Q

Define mitigation

A

actions and interventions that a community take to reduce vulnerability in advance of hazard

86
Q

Define adaptation

A

Ways communities make adjustments to the risk
Eg. Being able to live with a tectonic hazard

87
Q

Mitigation and adaptation can be further stratified as …..

A

Micro - strengthening individual buildings, ppl or structures

Macro - large scale protective measures designed to protect whole communities

88
Q

Modifying the event:

A

Modify the loss - aid, insurance

Modify vulnerability - predictability, education

Modify event - environmental control, hazard resistant design

Modify cause - hazard prevention (only rlly possible on small scale though)

89
Q

EQ modification strategy example

A

Strategy: public buildings and facilities strengthened to protect them from destruction. Ppl shelter in them to stay safe (hospitals, skls)

Example: Japan 2011

90
Q

Tsunami modification strategy example:

A

Strategy: engineering systems —> displace wave energy, shore vegetation, planting mangrove swamps

Example: great Asian tsunami of 2004, fewer deaths if coasts protected

91
Q

Volcanoes modification strategy example:

A

Strategy: spraying sea water onto lava to slow by chilling, 3D imaging of earths surface

Example: 1973 Iceland eruption

92
Q

Modifying the vulnerability: public education

A

Good education and better public awareness can help to reduce vulnerability and prevent hazards from becoming disasters

Eg. Regularly practicing emergency procedures

93
Q

Modifying the vulnerability: high tech monitoring

A

Accurate predictions

Allows scientists to learn more abt natural processes in the hope to predict them in advance and better

Reduces lives lost = reduces vuln

Eg. Early warning systems

94
Q

Modifying the vulnerability: crisis mapping

A

Local ppl provide info such as where ppl are trapped under rubble
These locations are then plotted onto maps by worldwide volunteers and placed online for everyone to see
Reduces lives lost = reduces vuln

Eg. Nepal 2015 EQ ppl rode bikes using GPS trackers to find ppl

95
Q

What steps do the gov. take to reduce losses following a tectonic event ?

A

Work with insurance companies to protect losses

Receive (and send) international aid

Implement disaster response teams

Adopt international frameworks for disaster management

96
Q

Aid donors

A

What is it?
Helps recover and rebuild. Types: emergency, short term (st) long term (LT)

How does it reduce losses?
Emergency - provides food, clean water, shelter
ST - restoring water supplies
LT - reconstruction

Case study:
Haiti 2010. Aid straight to gov

97
Q

NGOs

A

What is it?
Provide funds, coordinate search and rescue efforts and help develop reconstruction plans

How does it reduce losses?
Helps communities build resilience

Case study:
2005 Pakistan EQ
7.6 magnitude
NGOs provided half a million tents and safe water for 700k ppl

98
Q

Insurance companies

A

What is it?
Helps communities recover
Provided individuals and businesses the money they need to rebuild and repair

How does it reduce losses?
Ppl aren’t as economically affected

Case study:
Japan

99
Q

Communities

A

What is it?
Locals who are the first to respond

How does it reduce losses?
In rural communities it can take days for aid to arrive so they take recovery steps themselves

Case study:
Afghanistan EQ 2015. Mountain communities set up small groups to help with search and rescue in more remote areas

100
Q

What is hyogo framework for action? (HFA)

A

2005 world conference on disaster reduction agreed on the Hyogo Framework for Action to prioritise DRR. set out 4 priorities:
> understand disaster risk
› strengthen governance to manage disaster risk
› invest in DRR for resilience and effective response
> ‘build back better’ in recovery, rehabilitation and reconstruction

101
Q

What is the Sendai framework for disaster risk?

A

Organised by the UN as an attempt to provide a framework to reduce disaster risk for countries/ communities. The four priorities were:
1) Understanding disaster risk
2) Strengthening governance to manage disaster risk
3) Investing in disaster-risk reduction for resilience and enhanced disaster preparedness for effective response.
4) ‘Build Back Better’ in recovery, rehabilitation, reconstruction.

102
Q

Japan (HIC) disaster management/ recovery

A

3rd strongest economy in world

Able to develop due to disasters. Eg. Investments in seismic engineering such as roads with absorbers for seismic shocks

103
Q

Indonesia (NEE) disaster management/recovery

A

5.3M pop.
Located on ring of fire
Project for better housing and infrastructure
Pre disaster - represents the stage of the country or area within before disaster

Geography (7 decks)

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