Plate Tectonics (Factor of EQ, Hazards of EQs, risks and benefits of volcanoes) KQ2 Flashcards Preview

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Flashcards in Plate Tectonics (Factor of EQ, Hazards of EQs, risks and benefits of volcanoes) KQ2 Deck (43)
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1
Q

Factors affecting extent of EQ damage

A

1) Magnitude
2) Level of Preparedness
3) Population density
4) Distance from Epicenter & depth of focus
5) Type of Soil
6) Time of Occurrence

2
Q

How does Level Of Preparedness affect damage of EQ?

A

Def: amt of preparations takes by authorities and citizens
-Makes EQ more manageable and people are better prepared.

e.g. Tohoku EQ, 9.0 mag, 2011, Japan - 28,000 deaths
Haiti EQ, 7.0 mag, 2010, Carribeans - 300,000 deaths

3
Q

How does magnitude of EQ affect damage of EQ?

A

Greater Magnitude, larger extent of damage and destruction

4
Q

How does Population density affect damage of EQ

A

Def: Number of people living in the affected area
- Sparsely populated: less affected
- Densely populated: heavily affected, mass casualties and damage

5
Q

How does distance from epicenter affect damage of EQ?

A

Epicenter Def: Directly above focus on surface
- Closer the area to epicenter, the more severe the damage

6
Q

How does depth of focus affect damage of EQ?

A

Focus def: Origin of EQ in crust
-Affects magnitude of EQ

1) Deep Focus
- 70 - 700km below surface
- Seismic waves take longer time to reach surface = smaller impact
- Most energy lost to surroundings
- Lower magnitude

2) Shallow Focus
- 0-70km of crust
- Seismic waves reach land surface more quickly
- Less energy loss
- Higher magnitude

7
Q

How does timing of EQ affect damage of EQ?

A
  • Time determines where people are and what they are doing
  • Affects chance of survival
    -Night: Sleeping = trapped = more casualties
  • Day: Active = Quick responses = more survive

e.g. 2,400 deaths aft 1999 Sun Moon Lake EQ in Taiwan aft midnight.

8
Q

How does type of soil affect damage of EQ?

A

-Loose, unconsolidated soils amplify seismic wave vibrations = greater mg
- Saturated and unsettled sediments liquify under vibrations = sinking of infra (Liquifaction)

e.g. 2011, Christchurch, NZ.

9
Q

Tsunamis

A

Def: Large sea-waves formed by high-energy tectonic activities displacing large masses of water.

1) Seismic energy displaces huge volumes of water
2) Starts at heights of less than 1m, length of 100-150km and speeds of 800km/hr
3) When reaches shallower waters = greater friction = slow down = height increase
4) Reach heights of 15m and speeds of 30-50km/hr
5) Sea may retreat to fill void caused by movement of seafloor.

10
Q

Tsunami example

A

2004, 9.2 mag EQ, Indian ocean.
-Tsunami damaged coasts of 12 countries
- heights of up to 40m, reaching 10km inland

11
Q

Effects of Tsunamis and EQs

A

1) Disruption of services
2) Destruction of Infra
3) Destruction of property
4) Fires
5) Landslides
6) Loss of Lives

12
Q

How are services disrupted during tsunami/EQ?

A

Def: Disruption of essential services such as electricity, gas and water, affecting large areas

  • snap pipes, break cables, affect communication and power networks.
13
Q

Disruption of services (Tsu/EQ) example

A

Kobe EQ, Japan, 1995
-Damaged pipes, and transmission lines, affecting power gas and water
-Affected 1.4 million residents
-Burst gas pipes caused city wide fires

14
Q

Fires during EQ/tsu

A
  • Gas pipes burst, petrol gas escapes
  • Exposed cables may spark, setting flammable materials on fire
  • Fire can spread easily and quickly over large areas.
  • Causes injury and death
15
Q

Fires (EQ/tsu) example

A

Kobe EQ, Japan, 1995
-Toppled appliances sparked fires
- Firemen unable to manage fires due to no water supply, strong winds, extensive fuelling and fast spreading of fires.

16
Q

How are landslides caused during EQ/tsu

A

Def: Rapid downslope movement of soil, rock and vegetation debris from a slope

  • Vibrations destabalise soil
  • slopes weaken and sediments slide
  • Can reach speeds of 40 - >80km/h and stretch for a few km wide

-Mudflows occur when soil is saturated

17
Q

Landlisde (EQ/Tsu) example

A

Peru EQ, 1970
-Destabalised Mount Huascaran
-Landslides >160km/h
-Flattened town of Ranrahirca
-Killed, >18,000 people and only 200 survived.

18
Q

Destruction of property during EQ/tsu

A
  • Widespread destruction to homes
  • Displaces people
  • Restoration and reconstruction costly
19
Q

Destruction of property (EQ/tsu) Examples

A

Tohoku EQ, Japan, 2011
-Tsunami extended 10km inland
- Extensive structural damages and thousands displaced and left without homes

20
Q

Destruction of Infra During EQ/tsu

A

-Causes cracks and damage to infra
- Transportation to and within region affected (inaccessible)

21
Q

Destruction of Infra (EQ/tsu) examples

A

Kobe, 1995
- Inaccessible

Tohoku, 2011
- USD$300 billion in repairs

22
Q

Loss of Lives

A
  • Hazards threaten lives of people
  • Important for people to be prepared and take precautionary measures to minimise damages.
23
Q

Tohoku EQ, Japan, 2011

A

-Mag 9.0
- 28, 000 deaths
- 155,000 homes lost
- Nuclear power plant crippled
- Tsunami reached 10km inland
- USD$300 billion in damages

24
Q

Haiti EQ, Carribeans, 2010

A

-Mag 7.0
- 300, 000 deaths
- 1.3 million left homeless

25
Q

Sichuan EQ, China, 2008

A
  • Mag 8.0
  • 100, 000 deaths
  • 374, 000 injured
  • 15 million evacuated
  • 5.36 million buildings collapsed
  • Major landslide occured
26
Q

Risks of Volcanoes

A

1) Massive destruction by volcanic materials
2) Landslides
3) Pollution
4) Short term effects on weather

27
Q

Massive destruction by volcanic materials

A
  • Lava, pyroclasts and volcanic bombs
  • High temps of 500 - 1400c
    -Destroy and burn property

-Low silica lava / pyroclastic flows move rapidly and destroy anything in path

  • Inhalation of ash and gases cause injury and death
28
Q

Damage from volcanoes examples

A

Kilaueu Hawaii, 1983
- Constant eruptions damage houses and transport infra

29
Q

Landslides due to volcanic activity

A
  • Structural breakdown on volcanic cone
  • Debris obstruct rivers = flooding
  • Block Roads = hinder access
  • Bury Villages and farmlands
30
Q

Volcanic landslide examples (Lahars)

A

Nevado del Ruiz, South American Andes Mt.s, 1985
-Pyroclastic flow mixed with glacial ice, forming lahars
- Engulfed town of Armero and killed >20,000 people

31
Q

Pollution caused by Volcanic activity

A

1) Ground pollution
- Ash and pyroclast eventually settle, suffocating crops and burning surrounding
- Fine Ash block sunlight, prevent photosynthesis, killing crops

2) Air pollution
- Release of gases, CO2, SO2, CO, harmful to people and env
- Cause respiratory problems for people and animals

-Fine ash carried over long distances pollute env on larger scale

32
Q

Pollution from volcanic activity example

A

Icelandic Volcano, 2010
- Posed threat to airspace (air+ash pollution)
- Airspace closed over Europe and flights delayed
- 1.2 million passengers affected, USD$1.8 million lost

33
Q

Volcano effects on weather

A

-SO2 reacts with water vapour and chemicals in atmosphere to form sulfate aerosols

  • Aerosols reflect incoming shortwave radiation = temporary global cooling
34
Q

Volcano Effects on weather examples

A

e.g. Eruption of Mount Tambora, Indonesia, 1815
- Dropped global temperatures by 1.7c

e.g. Eruption of Mount Pinatubo, 1991
- Dropped global temperatures by 0.4c

35
Q

Benefits associated with Volcanoes

A

1) Fertile soil
2) Precious stones and minerals, building materials
3) Tourism
4) Geothermal energy

36
Q

Fertile Soil (vol)

A
  • Breakdown of lava, rocks and ash from fertile volcanic soils

A: Richest soils on earth = favourable for agriculture

L: Takes thousands of years for volcanic rocks to break down and release minerals/nutrient

37
Q

Fertile Soil (vol) examples

A

e.g. Java & Bali, Indonesia
- Soils support large rural populations over many decades
- Soils support wide cultivation of crops (tea, coffee, rice)

38
Q

Precious Stones and Minerals, building materials provided by volcanoes

A

1) Volcanic rocks rich in precious stones and minerals (Carbon under high heat, pressure and cooled in magma)

A: Used for industrial tools, scientific research and commercially sold as Jewellery

L: Extraction only after millions of years. Volcanic rocks have to erode and break down.

2) Volcanic rocks contain compounds useful for producing building materials and daily items

39
Q

Precious stones and minerals, building materials produced by volcanoes examples

A

e.g. Volcanic rocks of Kimberly, South Africa,
- Richest source of diamond in the world

e.g. Java, Indonesia
- Sulfur compounds collected and used to make matches, fertilisers and refined sugar

40
Q

Tourism from volcanoes

A

-Offer opportunity for various activities (hot springs, camping, scenery etc)

A: Volcanic areas usually rich in history- tourists interested to learn more.

41
Q

Tourism from volcanoes examples

A

e.g. Ruins of Pompeii, Italy
- Buried by layers of ash from mount Vesuvius in 79CE
- Unearthed archaeological site reveals well preserved buildings, poetry and mosaics
- Attracts >3million visitors per year

e.g. Taiwan & New Zealand
- Built facilities above hot volcanic rocks to provide Geothermal Spas

42
Q

Geothermal Energy from volcanoes

A
  • Derived from earths crusts
  • Groundwater heated by hot rocks, expands and rises as hot water and steam.

A: Utilised to run turbines and produce electricity

43
Q

Geothermal Energy examples

A

e.g. Iceland
- 70% of homes powered by volcanic steam