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1. CHAPTER 2
LIVING WITH
TECTONIC HAZARDS
Risk or Opportunity?

2. In this Chapter, you will explore three key
questions:
1.Why are some areas more prone to tectonic
hazards?
2.What landforms and associated tectonic
phenomena are found at plate boundaries?
3.How do people prepare for and respond to
earthquakes?
CHAPTER 2 LIVING WITH
TECTONIC HAZARDS

3. CHAPTER 2 LIVING WITH
TECTONIC HAZARDS
Gateway 2: What landforms and associated
tectonic phenomena are found at plate
boundaries?
The sea started to recede. I remember
learning in a geography lesson that this
happens before a tsunami. I shouted to tell
everyone a tsunami was coming and for
them to run!
Quoted from a survivor of the tsunami that took place at Mai Khao
Beach , Thailand on 26 December 2004.

4. In December 2004, The Tsunami swamps Phuket's Chedi resort (AFP/Joanne Davis)
Gateway 2: What landforms and associated
tectonic phenomena are found at plate
boundaries?

5. After the tsunami, authorities have now
installed signs along this coastline.
• What symbols and words would you expect to
see on these signs. Sketch the signs you
expect to see at the beach.
• Explain why you thought the signs are
important.

6. CHAPTER 2 LIVING WITH
TECTONIC HAZARDS
Gateway 2: What landforms and associated
tectonic phenomena are found at plate
boundaries?
a.Why are different landforms found at different plate
boundaries and how are they formed?
b.What phenomena are found at plate boundaries and how are
they formed?

7. What could have happened here?

8. Fold mountains
• Over millions of years, the folding of rocks creates a
landform called fold mountains.
• The Himalayas, the Rocky Mountains and the Andes
are examples of fold mountains.

9. • Fold mountains are formed along convergent
plate boundaries.
• The compressional force causes the layers of
rocks to buckle and fold.
• This process is known as folding.
Fold mountains

10. • The upfold is called the anticline and
• The downfold is the syncline.
• When there is increasing compressional force on one
limb of a fold, the rocks may buckle until a fracture
forms.
• The limb may then move forward to ride over the
other limb
Fold mountains

11. Fold mountains
The Himalayas
Peak : Mount Everest (between
Nepal and Tibet)
Elevation : 8,848 metres

12. • Fold mountains are located along convergent plate
boundaries
Describe the distribution of FM shown.

13. What could have happened here?
Describe what you see. [4]

14. Rift valleys and block mountains
• Rift valleys and block mountains are formed at
divergent plate boundaries.

15. • A fault is a fracture in the rocks along which
the rocks are displaced.
• The tensional forces result in parts of the
crust being fractured.
• This process is called faulting.
Rift valleys and block mountains

16. • A rift valley is a valley with steep sides formed along
fault lines.
• E.g. East African Rift Valley
Rift valleys and block mountains

17. • A block mountain is a block of land with steep sides.
It is formed when sections of the crust extend along
fault lines and rock masses surrounding a central
block sink due to tensional forces.
Rift valleys and block mountains

18. Explain the formation of Block
Mountains and Rift Valleys
Divergent plate
boundaries
Parts of crust
fractured in
faulting
Tensional
Forces
Pull apart Within a plate
Between
parallel faults
Form rift valley Sections of
crust extend
along fault
lines
Tensional
forces
Central block of
land subside
However When
tensional
forces
surround a
block of land
to subside
Block mountain
is form
Between
parallel fault
cause land
masses

19. Explain the formation of Block
Mountains and Rift Valleys
Divergent plate
boundaries
1
Parts of crust
fractured in
faulting
5
Tensional
Forces
2
Pull apart
4
Within a plate
3
Between a pair
of parallel
faults
To form a rift
valley
When Sections
of crust extend
along fault
lines
Tensional
forces
Can cause a
Central block of
land subside
However when
tensional
forces
surround a
block of land
to subside
A block
mountain is
form
Between
parallel fault
cause land
masses

20. Explain the formation of Block
Mountains and Rift Valleys
Divergent plate
boundaries
1
Parts of crust
fractured in
faulting
5
Tensional
Forces
2
Pull apart
4
Within a plate
3
Between a pair
of parallel
faults
4
To form a rift
valley
5
When Sections
of crust extend
along fault
lines
1
Tensional
forces
2
Can cause a
Central block of
land subside
3
However when
tensional
forces
surround a
block of land
to subside
A block
mountain is
form
Between
parallel fault
cause land
masses

21. Explain the formation of Block
Mountains and Rift Valleys
Divergent plate
boundaries
1
Parts of crust
fractured in
faulting
5
Tensional
Forces
2
Pull apart
4
Within a plate
3
Between a pair
of parallel
faults
4
To form a rift
valley
5
When Sections
of crust extend
along fault
lines
1
Tensional
forces
2
Can cause a
Central block of
land subside
3
However when
tensional
forces
1
surrounding a
block of land
to subside
3
A block
mountain is
form
4
Between
parallel fault
5
cause land
masses
2

22. Rift valleys and block mountains
The East African Rift Valley
Is formed from the Nubian
section of the African Plate and
the Somalian section of the
African Plate pulling away from
one another.

23. • Describe the distribution of rift valleys
and block mountains

24. What could have happened here?

25. Volcanoes
• A volcano is a landform formed by magma ejected
from the mantle onto the earth’s surface.
Mount Saint Helens volcano before and after an eruption in May
1980

26. • Magma is molten rock found below the earth’s
surface.
• Parts of a Volcano
- magma chamber
- vents
• Magma that is ejected onto the surface is known
as lava.
Volcanoes

27. Volcanoes
Formation, structure of, and features of a volcano

28. Shapes and sizes of volcanoes
• Volcanoes vary in shapes and sizes due to the
characteristics of the lava.
• Viscosity refers to the stickiness of the lava
• The most common types of volcanoes are:
- Shield volcanoes; and
- Stratovolcanoes
Volcanoes

29. Shield volcanoes
• Shield volcanoes have gently sloping sides and a broad
summit
• The low silica lava flows easily and spreads over a large
area before solidifying.
• As lava do not trap much gas, eruptions are generally not
explosive.
• Successive eruption cause the base of the volcano to
increase in size.
Volcanoes
E.g. Mount
Washington,
United States
of America

30. Why are shield volcanoes shaped
with a broad based and gentle
sloping sides?

31. Stratovolcanoes
• Stratovolcanoes develop from successive eruptions of lava
and ash.
• Initital explosion of pyroclastic flow because the high silica
lava traps gases.
• Followed by alternate layers of lava and pyroclastic flow
again.
• The lava prevents the pyroclasts from being eroded away.
• Successive eruptions build high volcano.
Volcanoes
E.g. Mount
Mayon,
Philippines

32. Compare between Shield and Stratovolcanoes
Characteristics Shield Volcanoes Stratovolcanoes
Shape Broad summit
Broad base
High volcano with slightly
concave profile
Height? x x
RELIEF Gentle sloping sides Steeper at the top
Gentler at the base
Type of lava Low silica content
Low viscosity
High silica content
High viscosity
Type of eruption Gentle Explosive
Frequency of eruption X X
Where it occurs? Usually at Oceanic-
Oceanic plate divergence
Or at hotspots
Usually at Continental-
Oceanic plate convergence

33. Volcanoes
Distribution of earth’s major active volcanoes

34. • An earthquake is a vibration in the earth’s crust caused by the
sudden release of stored energy in the rocks found along
fault lines.
b. What phenomena are found at plate
boundaries and how are they formed?

35. • Measuring earthquakes
- A seismograph records the seismic waves released
by an earthquake.
Earthquakes

36. • Extent of earthquakes
- The Richter Scale is used to measure the magnitude
of an earthquake
Earthquakes

37. Ecuador Earthquake 17 April 2016
7.8 Ritcher Scale – 11.26 p.m.
• http://www.mapsofworld.com/thematic-maps/earthquake/ecuador.html
1) What is the
extent of the
damage / impact
of the the EQ?
2) How long do
you think the
aftershocks may
last?
3) Why would
Ecuador suffer a
greater impact
than compared to
Taiwan?

38. Date Ritcher
Scale
Death
estimate
Injured
estimate
17 April (Sat) 7.8 272 2500
18 April 7.8 272 (am)
410 (pm)
Over 2000
20 April 6.1 Over 2000
21 April 6.0 Over 2000

39. Ecuador Earthquake 17 April 2016
7.8 Ritcher Scale – 11.26 p.m.
• https://www.youtube.com/watch?v=bWzruH2KcR8
• Three Deadly Earthquakes Strike in 3 Days
1) Do you think there might be patterns involved in the movements of the
plates?

40. • Apart from its magnitude, the extent of damage
caused by an earthquake may vary based on other
factors:
- Population density
- time of occurrence
- level of preparedness
- distance from the epicentre
- type of soil
Earthquakes

41. Describe distribution of the earth’s major earthquakes
Earthquakes

42. Hazards associated with living in earthquakes zones
- Threat of tsunamis
- Disruption of services
- Fires
- Landslides
- Destruction of properties
- Destruction of infrastructure
- Loss of lives
Earthquakes

43. What happened here?

44. Threat of tsunamis
• Tsunami refers to an usually large sea wave.
• Tsunamis may be formed by:
- The movement of the sea floor during a large earthquake
at subduction zones;
- An underwater volcanic eruption;
- An underwater landslide; and
- A landslide above sea level which causes materials to
plunge into the water.
Hazards associated with earthquakes

45. Hazards associated with earthquakes

46. • In 2004, a 9.2 magnitude triggered a tsunami with
waves spreading throughout the Indian Ocean.
Aceh before and after the tsunami hit the area
Hazards associated with earthquakes

47. The spread of the tsunami waves caused by the tsunami
Hazards associated with earthquakes

48. What happened here?

49. What happened here?

50. What happened here?

51. What happened
here?

52. Disruption of services
• An earthquake can disrupt services such as the
supply of electricity, gas and water.
• The earthquake in Kobe, Japan, in 1995 disrupted
electricity, gas and water supplies to about a million
of Kobe city’s 1.4 million residents.
Hazards associated with earthquakes

53. Fire
• Earthquakes may rupture gas pipes and this can
provide fuel to start fires.
• For example, the earthquake in Kobe, Japan, in 1995
caused extensive fires.
Hazards associated with earthquakes

54. Landslides
• Landslides are rapid downslope movements of soil,
rock and vegetation. Mudflows may also occur when
there is heavy rainfall.
Hazards associated with earthquakes

55. Destruction of properties
• Earthquakes can cause destruction to many homes.
• People may be without homes after the disaster.
Hazards associated with earthquakes

56. Destruction of infrastructure
• Earthquakes may cause cracks to form in
infrastructure such as roads and bridges.
• Transportation can be disrupted as it is unsafe to use
the damaged roads.
Hazards associated with earthquakes

57. Loss of lives
• Earthquakes and their associated hazards often
threaten the lives of those living in earthquake zones.
Hazards associated with earthquakes

58. Hazards associated with earthquakes

59. Volcanic eruptions
- Occurs on land occur on the sea floor.
Active, dormant or extinct
• Active volcanoes refers to volcanoes which are currently
erupting or are expected to erupt in the future.
• Dormant volcanoes are currently inactive but may erupt
in the near future.
• Extinct volcanoes refers to volcanoes without current
seismic activity
b. What phenomena are found at plate
boundaries and how are they formed?

60. Risks of living near volcanic areas
Some of the risks associated with living near volcanic
areas include:
• Destruction by volcanic materials
• Landslides
• Pollution
• Effects on weather
Volcanic eruptions

61. Destruction by volcanic materials
• Volcanic materials can lead to widespread damage of
property.
Volcanic eruptions

62. Some Volcanic Hazards
Volcanic Gases
Mudflows
Lava flow
Ash fall
Lightning strikes
Pyroclastic flows / surges
(high-density mixtures of hot, dry rock fragments
and hot gases that move away from the vent that
erupted them at high speeds)

72. Landslides
• Landslides can occur due to the structural collapse of a
volcanic cone.
• Obstruct the flow of rivers which causes floods,
• block roads, and
• bury villages and farmlands.
Volcanic eruptions

73. Pollution
• Ash particles may block sunlight, suffocate crops, and
cause severe respiratory problems for people and
animals.
• Release of gases may be harmful to people.
Volcanic eruptions

74. Volcanic eruptions
Eruption of Eyjafjallajokull affected jets.
http://mountaincatgeology.wordpress.com/2011/02/19/the-
2010-eruptions-ofeyjafjallajokull

75. Effects on weather
• Sulphur dioxide released from volcanic eruptions
has impacts on the environment
• It may react with water vapour and other
chemicals in the atmosphere to form sulphur-
based particles.
• These particles reflect the sun’s energy back into
space and temporarily cool the earth for periods
of time.
Volcanic eruptions

76. Benefits of living near volcanic areas
• Fertile volcanic soil
• Building materials, and precious stones and
materials
• Tourism
• Geothermal energy
Volcanic eruptions

77. Fertile volcanic soil
• Lava and ash from the volcanic eruptions break
down to form fertile volcanic soils.
• Favourable to agriculture
Volcanic eruptions

78. Precious stones and minerals, building materials
• Volcanic rocks can be rich in precious stones and
minerals.
• These resources can only be from a volcanic area
after millions of years.
• An example is diamond.
Volcanic eruptions

79. Tourism
• Volcanic areas offer a variety of activities for
tourists to engage in.
• The ruins of Pompeii, Italy, is one such example.
Volcanic eruptions

80. Pompeii was partially destroyed and buried under 4
to 6 m (13 to 20 ft) of ash and pumice in the
eruption of Mount Vesuvius in CE 79.
Volcanic eruptions

81. Geothermal energy
• Geothermal energy is derived from the heat in the
earth’s crust.
• The hot water or steam can be harnessed to produce
electricity.
Volcanic eruptions

82. CHAPTER 2 LIVING WITH
TECTONIC HAZARDS
Gateway 2: What landforms and associated
tectonic phenomena are found at plate
boundaries?
a. Why are different landforms found at different plate
boundaries and how are they formed?
b. What phenomena are found at plate boundaries and how are
they formed?

83. Practice Questions
• Describe the types of impacts of volcanic
eruptions. (6)
• Clue : How can you classify impacts?

84. Practice Questions
“The amount of damage and the number of
deaths is dependent on the strength of the
earthquake.” Discuss. (8)
•Clue 1 : What is the relationship between the
variables? Support
•high magnitude earthquakes vibrate and shake the
ground more violently, causes greater destruction
•Clue 2 : Is this relationship always the way it is?
•Clue 3 : Why not? Dependent on …

85. • reasons for exceptions:
– type of soil,
– level of preparedness (incl. education),
– distance from epicenter,
– earthquake resistance infrastructure,
– population density