This document provides an overview of seismicity and earthquakes. It discusses seismic waves, earthquakes and faults, measures of earthquakes including magnitude and intensity, ground damage from earthquakes, tsunamis caused by earthquakes, and earthquake resistant construction. Specific topics covered include the 2001 Gujarat earthquake in India and the devastating 2004 Indian Ocean tsunami. The document aims to introduce students to key concepts regarding seismicity and earthquakes.

1. UNIT FIVE: SEISMICITY
As per the Syllabus According to our Omnibus
 Seismic waves  Introduction to Earth
 Earthquakes and faults  Tectonic Plates
 Measures of an earthquake -  Faults
magnitude & intensity  Fundamentals of Earthquakes
 Ground damage  Earthquakes and Tsunamis
 Tsunamis and earthquakes  Ground Damage and Failure
 Earthquake Resistant Design and
Construction
 The Great Indian Ocean Tsunami, 2004
 Gujarat Earthquake, 2001

2. INTRODUCTION TO
EARTH

3. SOME FACTS ABOUT THE EARTH
Earth is the only planet to be named in English. The
word ‘Earth’ is Old English word for "land“
Earth belongs to the Milky Way Galaxy, Local Group
Cluster and Virgo Super Cluster
Earth is the only planet to sustain life
Earth is believed to be existent for 450 million years
& evidences are from 225 million years

4. SOME FACTS ABOUT THE EARTH

5. SOME FACTS ABOUT THE EARTH
Earth is the third planet from the sun
Earth is the fifth largest planet in the universe
The distance of the earth from the sun is 149,600,000 km
The diameter of the sun is 100 times the diameter of the
earth
The mass of the earth is 5.972 x 1024 kg
The Surface area of earth is 510,072,000 km²

6. SOME FACTS ABOUT THE EARTH
Before 500 BC, people thought that earth was flat. But
thanks to scientists like Aristotle and Pythagoras, people
know that the shape of the earth is spherical. However Sir
Isaac Newton showed that the earth was not a perfect
sphere, but a compressed spheroid.
The correct technical term to use will be oblate spheroid, a
type of ellipsoid solid formed when an ellipse is rotated
about its minor axis.
The study of size and shape of earth is called geodesy.
The diameter of earth at poles is 12715 km (minor axis)
The diameter of earth at equator is 12763 km (major axis)

7. STRUCTURE OF EARTH
The structure of earth (also
referred as cross–section) is
divided into mainly four layers
namely Crust, Mantle, Inner
Core and Outer Core.

8. STRUCTURE OF EARTH
Divisions,Thickness & Materials of the layer

9. STRUCTURE OF EARTH
CRUST
The outermost layer of the Earth is the crust. It is also the surface of the earth.
This comprises the continents and ocean basins and therefore it has been
classified into continental crust and oceanic crust.
The oceanic crust extends up to a distance of 0-10 kms (5-12 taken as
average) whereas the continental crust would extend up to 0-75 kms (20-70
taken as average).
The oceanic crust is mainly composed of basaltic igneous rocks, mainly of
silica and magnesium and therefore also called SIMA layer.
The continental crust is composed of crystalline and granitic rocks mainly of
silica and aluminum and therefore also called SIAL layer.

10. STRUCTURE OF EARTH
MANTLE
The next layer is the mantle, which is composed mainly of iron and
magnesium silicates. It is been referred as FeMa layer.
Mantle is also where most of the internal heat of the Earth is located. It is
about 2900 km thick.
It can be subdivided into four layers namely
(1) Lithosphere (70 – 100 kms)
(2) Asthenosphere (100 - 350 kms)
(3) Upper Mantle (350 – 670 kms)
(4) Lower Mantle (670 – 2900 kms)
Mohorovičić discontinuity, usually referred to as the Moho is the transition
boundary between the Earth's crust and the mantle.

11. STRUCTURE OF EARTH
MANTLE
The lithosphere is the outermost part of the mantle immediately below the
Mohorovičić discontinuity. It has a part of the tectonic plates that cover
surface of Earth.
Asthenosphere is a low seismic velocity zone where rocks are at or near
melting point. It also has a part of tectonic plates.
The lower mantle is probably mostly silicon, magnesium and oxygen
with some iron, calcium and aluminum.
The upper mantle is made up of mostly olivine and pyroxene
(iron/magnesium silicates), calcium and aluminum

12. STRUCTURE OF EARTH
OUTER CORE
The third layer is outer core. The outer core is a hot and liquid layer
comprising mainly of Nickel and (liquid) Iron. Therefore it is referred as NiFe
Layer.
The outer core may also contain lighter elements such as Si, S, C, or O.
The outer core ranges from 2900 kms to 5150 kms and is 2300 km thick.
The Earth's magnetic field is believed to be controlled by the liquid outer
core. It is also believed to be the responsible force of earth’s rotation and
electric currents.
The transition space between outer core and mantle is called Gutenberg
discontinuity

13. STRUCTURE OF EARTH
INNER CORE
The fourth layer is inner core.
This layer stretches from 5150km to 6370 km and is nearly 1200 km
thick.
The inner core is mostly made of solid iron and has little amounts of
nickel.
It is unattached to the mantle and is suspended in the molten outer core.
The inner core is believed to have the extreme temperature and pressure
conditions.
The transition region between outer core and inner core is called Lehmann
discontinuity

15.  What is tectonic plates?
 What are the different tectonic plates?
 What is the history of tectonic plates?
 Do the tectonic plates move?
 Briefly explain the movement of plates?
 What is continental drift?
 What is the evidence of tectonic plate movement?
 How do tectonic plates cause earthquakes?
 What are intraplate and interplate earthquakes?

16. The lithosphere is divided into several slabs or
blocks or plates. These plates are supported from
below by Asthenosphere. These plates are called
Lithosphere plates or Tectonic Plates.
Some of these plates encompass continents, some
of these plates encompass oceans and some of the
plates encompass both oceans and continents.

18. The plates are divided into three categories
Primary Plates
Secondary Plates
Tertiary Plates
The primary plates and secondary plates are together
called major plates.
The tertiary plates are sub divisions of Primary and
Secondary Plates

19. Primary
African Plate
Antarctic Plate
Eurasian Plate
Indo-Australian Plate (sometimes Indian and Australian)
North American Plate
Pacific Plate
South American Plate
Secondary
Arabian Plate
Caribbean Plate
Cocos Plate
Juan de Fuca Plate
Nazca Plate
Philippine Sea Plate
Scotia Plate

23. 225 million years ago (Permian)
PANGAEA
200 million years ago (Triassic)
LAURASIA, GONDWANA
125 million years ago (Jurassic)
NENA,COLUMBIA,ZEALANDIA
65 million years ago (Cretaceous)
LEMURIA
CURRENT
150 million years later
AMASIA

29. FUTURE

31. The movement of tectonic plates is believed to be induced
by the asthenosphere which induces heat and convection
currents.
The plates are capable of drifting with respect to each other
along their plate boundaries.
Based on the plate movement, there are 3 principal type of
boundaries namely
Diverging Boundaries
Converging Boundaries
Transform Boundaries

32.  Divergent Boundary – moving _____
 Convergent Boundary – moving ________
 Transform Fault Boundary – moving _____________

36. EXAMPLES
Divergent Boundaries
North American Plate & Eurasian Plate
Convergent Boundaries
South American Plate & Nazca Plate
Transform Boundaries
North American Plate & Pacific Plate near the JDF Plate

38. PLEASE NOTE
When two continental plates diverge, a rift is created.
Eg. East African Rift
When two oceanic plates diverge, a ridge is created. Sea
Floor Spreading is said to occur.
Eg. Mid Atlantic Ridge
When two oceanic plates converge, an island arc and
trench are created.
When an oceanic and convergent plate converge, a volcano
and trench are created.
When two continental plates converge, a mountain range is
formed.

39. PLEASE NOTE
When two continental plates or oceanic plates or
continental/oceanic plates transform, EARTHQUAKE
HAPPENS
If one plate is trying to move past
the other, they will be locked until
sufficient stress builds up to cause
the plates to slip relative to each
other. The slipping process creates
an earthquake .

40. 6. WHAT IS CONTINENTAL DRIFT?
The movement of earth’s continents with respect to each
other due to the movement of tectonic plates is called
continental drift.

41. 7. EVIDENCES FOR
TECTONIC PLATE MOVEMENT
SIMILAR PLANT & ANIMAL FOSSILS IN CONTINENTS
SIMILAR LIVING ORGANISMS
SIMILAR ROCK TYPES ON CONTINENTS
COMPLEMENTARY ARRANGEMENT OF FACING SIDES OF SOUTH
AMERICA & AFRICA
SEAFLOOR SPREADING DATA

42. 8. INTRAPLATE & INTERPLATE EARTHQUAKES
1. An intraplate earthquake is an earthquake that occurs in the
interior of a tectonic plate, whereas an interplate earthquake is one
that occurs at a plate boundary or a plate margin.
2. Intraplate earthquakes are very rare whereas interplate
earthquakes are quite normal. The recurrence interval of intraplate
earthquake is 10 – 30 years while that of interplate earthquakes is
100 – 1000 years.
3. The effect (magnitude and intensity) of intraplate earthquakes is
less when compared with interplate earthquakes.
4. Notable examples of damaging intraplate earthquakes are the
devastating Gujarat earthquake in 2001 while that for interplate
earthquakes are Chile 1960 Earthquake and

43. FAULTS

44. THE TWO MOST IMPORTANT REASONS FOR
EARTHQUAKES
 1. TECTONIC PLATES
 2. FAULTS

45. FAULTS
 FAULTS ARE ONE OF THE STRUCTURAL
FEATURES OF ROCKS
 WHILE ROCKS AT OR NEAR THE
SURFACE OF THE EARTH ARE COOL &
BRITTLE, ROCKS BELOW THE SURFACE
OF THE EARTH ARE HOT AND TEND TO
MOVE

46. FAULTS
 A LOT OF EXTERNAL FORCES ACT UPON
THE ROCKS AND CAUSE STRESS ON THEM
 DUE TO THIS STRESSES, ROCKS EITHER
UNDERGO DUCTILE DEFORMATION(BEND)
OR BRITTLE DEFORMATION(BREAK)
 IF THEY UNDERGO DUCTILE
DEFORMATION, ROCKS DEVELOP FOLDS.
IF THEY UNDERGO BRITTLE
DEFORMATION, THEY DEVELOP FAULTS.

47. FAULTS

48. FAULTS
 FAULT IS DEFINED AS A SPLIT OR CRACK
OR FRACRTURE IN THE ROCK PRESENT IN
EARTH’S CRUST CHARACTERISED BY
RELATIVE DISPLACEMENT OF ONE SIDE
OVER THE OTHER.
 The two sides of a non-vertical fault are known
as the hanging wall and footwall. By definition,
the hanging wall occurs above the fault plane
and the footwall occurs below the fault

49. FAULTS

50. FAULT LINE
 A FAULT LINE IS THE INTERSECTION OF
A FAULT PLANE AND EARTH SURFACE
 IT IS THE SURFACE TRACE OF A FAULT

51. FAULT LINE

52. TYPES OF FAULTS
 FAULTS ARE CLASSIFIED INTO THREE
TYPES NAMELY
 DIP SLIP FAULTS (VERTICAL MOTION)
 STRIKE SLIP FAULTS (HORIZONTAL
MOTION)
 OBLIQUE SLIP FAULTS (OBLIQUE
MOTION)

53. TYPES OF FAULTS

54. DIP SLIP FAULTS
 A fault where the relative movement on the
fault plane is approximately vertical is known
as a dip-slip fault.
Dip Slip Faults are divided into
Normal Faults (Extension)
Reverse Faults/Thrust Faults (Compression)

55. NORMAL FAULTS

56. REVERSE FAULTS

57. DIP SLIP FAULTS
 When the hanging wall moves down with
respect to the footwall, it is called a normal
fault.
 When the hanging wall moves up relative to
the footwall, it is called a reverse fault

58. STRIKE SLIP FAULTS
 A fault where the relative movement on the
fault plane is approximately vertical is known
as a strike-slip fault.
 Strike Slip Faults are divided into
Left Lateral Faults (Sinistral Faults)
Right Lateral (Dextral Faults)

59. LEFT LATERAL FAULTS

60. RIGHT LATERAL FAULTS

61. STRIKE SLIP FAULTS
 If you stand on one side of a fault and the other
side slips to the right, then it is called a right-
lateral fault.
 In a left-lateral fault, the movement occurs to
your left.

62. SIMPLE DIAGRAMATIC REPRESENTATIONS

63. OBLIQUE SLIP FAULTS
A fault where the relative movement on the fault plane is both
horizontal and vertical is known as a oblique-slip fault.

64. FAULTS & EARTHQUAKES

65. FAULTS & EARTHQUAKES
FAULTS CAN CAUSE TREMENDOUS
EARTHQUAKES
STRIKE SLIP FAULTS CAUSE MAJOR
EARTHQUAKES WHILE OBLIQUE SLIP
FAULTS AND DIP SLIP FAULTS CAUSE
MINOR EARTHQUAKES.
THE OCCURRENCE OF EARTHQUAKES
DUE TO FAULTS IS EXPLAINED BY ELASTIC
REBOUND THEORY.

66. ELASTIC REBOUND THEORY

67. ELASTIC REBOUND THEORY

68. ELASTIC REBOUND THEORY
 The elastic rebound theory is an explanation
for how energy is spread during earthquakes.
As plates on opposite sides of a fault are
subjected to force and shift, they accumulate
energy and slowly deform until their internal
strength is exceeded. At that time, a sudden
movement occurs along the fault, releasing
the accumulated energy, and the rocks snap
back to their original undeformed shape.

69. FUNDAMENTALS OF
EARTHQUAKES

70. CONTENTS
1. DEFINITION OF AN EARTHQUAKE
2. EARTHQUAKES & SEISMICS
3. CENTRES AND SHOCKS
4. INTENSITY AND MAGNITUDE OF EARTHQUAKES
5. CAUSES OF EARTHQUAKE
6. SEISMIC WAVES
7. EFFECT OF EARTHQUAKES
8. WORLD SEISMIC ZONES
9. SEISMIC ZONES OF INDIA

71. Earthquake may simply expressed as a momentary
shock experienced by the earth at a particular location
and time.
Earthquake may be technically defined as the vibrations
induced in the earth’s crust due to internal or external
causes that give a shock to a part of the crust and all
things existing on it

72. The greek word for earthquake is
Seism and therefore the term seismic
is associated with earthquakes.
The science dealing with the study of
earthquakes is called seismology
The word seismic is used to qualify
anything related to earthquake such
as seismic intensity, seismic zoning,
seismic waves etc.

73. FOCUS OR HYPOCENTRE
The point of origin of an earthquake below the surface of earth.
EPICENTRE
The point on the surface directly above the focus where the vibrations
are felt.

74. SHOCKS
A large earthquake is generally preceded and followed by
many smaller shocks.
The largest earthquake is called the main shock. The
smaller ones that occur before the main shock are called
foreshocks and the shocks that occur after the main shock
are called aftershocks.

75. INTENSITY MAGNITUDE
Intensity is a term used to Magnitude is a term used
measure the impact of to establish the size of an
earthquake. earthquake.
Intensity measures the It is a measure of the
strength of shaking amplitude of a seismic
produced by the wave and is related to the
earthquake at a certain amount of energy released
location. during an earthquake.
Intensity is determined Magnitude is the total
from effects on energy released by an
people, human earthquake at its focus.
structures, and the natural
environment. The Richter Scale is most
famous to express the
Mercalli Scale was used magnitude of an
to predict intensity. earthquake.

76. INTENSITY AND MAGNITUDE
Magnitude and Intensity measure different
characteristics of earthquakes. Magnitude is quantitative
and measured using instrument called seismograph.
Intensity is qualitative and can be measured using
assessment of the damages.

77. INTENSITY AND MAGNITUDE
The analogy of tube light is used to differentiate between
magnitude and intensity.

78. MAGNITUDE
Magnitude is the logarithm to base 10 of maximum
amplitude traced on the seismogram by an instrument
placed at 100 km from the epicenter.
It can be generally calculated by the formula
M = log (A∆/Ao∆) where
M is Richter magnitude
∆ is epicentral distance
A is amplitude of the point to be measured
Ao is the maximum amplitude of zero earthquake

79. INTENSITY
Intensity is a space dependent descriptive rating of
changes observed to the ground surface in terms of
damaging effects. The damaging effects are ground
damage, damage to built environment and to the
humans. These effects are incorporated in a descriptive
intensity scale by a group of experts and denoted by
Roman numbers. Maximum intensity is usually close to
the epicenter and it reduces as the epicentral distance
increases. The lines of same intensity are plotted in a
contour map called isoseismal map which is a very
important data for earthquake analysis.

80. Nowadays intensity of earthquakes are not measured.
They have been replaced by magnitude.
Top 5 Earthquakes by Magnitude
S. Date Place Magnitude
No.
1 22 May 1960 Valdivia, Chile 9.5
2 27 March 1964 Alaska, USA 9.2
3 26 December Sumatra, Indonesia 9.1
2004
4 13 August 1862 Arica,Chile 9.0
5 26 January 1700 Cascadia, USA- 9.0
Canada

81. An earthquake may be caused by the following natural and artificial
sources.
NATURAL SOURCES
Tectonic Plates Movement 90%
Faults in Rocks (Elastic Rebound Theory) 6%
Volcanic Explosions 1%
ARTIFICIAL SOURCES
Explosion 1%
Mine Collapse 1%
Reservoir Failure 1%

82. SEISMIC WAVES
The energy released during earthquake travels to the
earth in form of waves.
The waves are called as
P-Waves
S-Waves
L-Waves (Rayleigh Waves & Love Waves)
P-Waves & S-Waves are called as body waves.
L- Waves are also called as surface waves.

83. The seismic waves are very useful as follows
 They were used to establish the internal structure of the earth.
 They are used to calculate the magnitude of earthquake. Richter
Scale is based upon the amplitude of the seismic waves.
 They are also used to locate the epicenter of earthquakes.
 They are also used for groundwater and other explorations.

85. Primary, or P waves are the first waves felt during
an earthquake and they are the fastest.
They move in a compressional, "push-pull"
manner similar to a spring
They are longitudinal in character. They move
only in the direction of prorogation.
They temporarily change the volume of the
material they're moving through.
They can travel through liquid, solid and gaseous
matter.
Their velocity increases with depth and decreases
after the Gutenberg Discontinuity.

86. Secondary, or S waves, are felt next to P
waves.
These waves move in an
oscillatory/distortional manner similar
to shaking a rope.
They are transverse in character. They
move perpendicular to the direction of
prorogation.
They temporarily change the shape of
the material they're traveling through
They can travel through solids only.
Their velocity increases with depth and
they are absent beyond mantle.

87. L Waves or Long Waves or Surface
Waves are finally felt, are felt next
to S waves.
They are of two types namely – Love
Waves and Rayleigh Waves
Rayleigh Waves move in a complex
manner. They partly move in
direction of propagation and
partly perpendicular to the
direction of prorogation.
Love Waves move in the direction of
propagation horizontally but in
sideways.
It is only the Surface Waves cause
damage to the building.

91. The effects of earthquakes
Loss of Life
Building Collapse
Ignition of Fire
Ground Failure and Rupture
Landslides and Avalanches
Floods and Tidal Sources
Tsunami
Change in Soil and Rock Properties

92. WORLD SEISMIC ZONES
or EARTHQUAKE HOTSPOTS
Based on seismicity, the three most happening earthquake hotspots
in the world are
1. PACIFIC RING OF FIRE
2. ALPIDE BELT
3. MID ATLANTIC RIDGE

96. EARTHQUAKES IN INDIA
The major earthquakes in India are
2004 Sumatra Earthquake (9.1)
1934 Bihar Earthquake (8.7)
1950 Assam (Shillong Plateau) Earthquake (8.7)
1897 Assam (Tibetian Plateau) Earthquake (8.5)
2005 Kashmir Earthquake (7.6)
2001 Gujarat(Kutch) Earthquake (7.1)

97. EARTHQUAKES IN INDIA

98. EARTHQUAKE ZONES IN INDIA
There are five seismic zones named as I to V based on Modified Mercalli
Scale (MM Scale) as details given below:
Zone V: Covers the areas liable to seismic intensity IX and above on MM
Scale. This is the most severe seismic zone and is referred here as Very
High Damage Risk Zone.
Zone IV: Gives the area liable to MM VIII. This, zone is second in severity to
zone V. This is referred here as High Damage Risk Zone.
Zone III: The associated intensity is MM VII. This is termed here as
Moderate Damage Risk Zone.
Zone II: The probable intensity is MM VI. This zone is referred to as Low
Damage Risk Zone.
Zone I: Here the maximum intensity is estimated as MM V or less. This zone
is termed here as Very Low Damage Risk Zone.

101. EARTHQUAKE ZONES IN INDIA
Zone V: Kashmir, Punjab, the western and Central Himalayas, the North-
East Indian region and the Rann of Kutch fall in this zone.
Zone IV: Indo-Gangetic basin and the capital of the country(Delhi, Jammu)
and Bihar fall in Zone 4.
Zone III: The Andaman and Nicobar Islands, parts of Kashmir, Western
Himalayas, Western Ghats fall under this zone
Zone II: Other parts of India namely Hyderabad, Lakshadweep, Orissa etc.
Zone I : No

102. EARTHQUAKE ZONES IN INDIA
Cities and Zones
• Zone III :- Ahemdabad, Vadodara, Rajkot, Bhavnagar, Surat,Mumbai,
Agra, Bhiwandi, Nashik, Kanpur Pune, Bhubneshwar, Cuttack, Asansol,
Kochi, Kolkata, Varanasi, Bareilly, Lucknow, Indore, Jabalpur, Vijaywada,
Dhanwad, Chennai, Coimbatore, Manglore, Kozhikode ,Trivandrum.
• Zone IV :- Dehradun, New Delhi, Jamunanagar, Patna, Meerut, Jammu,
Amristar,Jalandhar.
• Zone V:- Guwahati and Srinagar.

103. Earthquakes
and Tsunamis

104. Overview
 Meaning of the word Tsunami
 Definition of Tsunami
 Characteristics of Tsunami
 Tsunami Effects
 Tsunami Vs Tsunami 2004
 Formation of Tsunami
 Tsunami Counter Measures

105. Tsunami- Name Meaning
IN JAPANESE
TSU – HARBOUR
NAMI – WAVES
TSUNAMI means HARBOUR WAVES

106. Tsunami- Definition
TSUNAMI IS DEFINED AS SERIES OF
GIGANTIC WAVES TRIGGERED IN A
LARGE BODY OF WATER BY A
DISTURBANCE (LIKE
EARTHQUAKE, VOLCANO, LANDSLI
DE, METEORITE ETC) THAT
DISPLACES WATER VERTICALLY.
TSUNAMI HAS SERIOUS EFFECTS IN
LOW LYING COASTAL AREAS. IT IS
MOSTLY CAUSED BY SUBMARINE
EARTHQUAKES

107. Tsunami- Characteristics
 A TSUNAMI IS CAUSED BY AN EARTHQUAKE WHICH HAS ITS
FOCUS LESS THAN 50 km
 A TSUNAMI IS CAUSED BY AN EARTHQUAKE WHOSE
MAGNITUDE IS NORMALLY MORE THAN 9.5
 THE WAVELENGTH OF A TSUNAMI CAN BE IN THE ORDER OF
100 – 200 KM
 THE AMPLITUDE OF TSUNAMI WILL BE BETWEEN 0.3m and
0.6m
 TSUNAMI CAN OCCUR FOR A PERIOD AS LOW AS 5 MINUTES
TO AS LONG AS ONE HOUR
 THE VELOCTITY OF TSUNAMI IS ABOUT 200 m/s or 720 km/hr.

108. Tsunami- Characteristics
 THE WAVELENGTH, PERIOD ,AMPLITUDE AND VELOCITY OF A
TSUNAMI ARE DEPENDENT ON THE DIMENSIONS OF THE
EARTHQUAKE AND THE DEPTH OF WATER.
 A TSUNAMI OFTEN COMES IN A SERIES OF WAVES , MAY
THREE TO FIVE MAJOR OSCILLATIONS SEPERATED BY SMALL
INTERVALS OF HALF AN HOUR OR SO.
 THE TSUNAMI WAVES CAN STRIKE AS HIGH AS 20 – 40 m (60 ft
– 140 ft)

109. Tsunami- Characteristics
 THE TSUNAMI WAVES ARE CHARACTERISED BY
APPROACH(COMING IN) AND RETREAT(RECEDING OUT).
APPROACH AND RETREAT CAN BE EQUALLY DANGEROUS.
 THE VELOCITY OF TSUNAMI CAN BE CALCULATED BY
FORMULA V2 = (gD) where
 V = velcity of waves in m/s
 g = acceleration due to gravity in m/s2
 D = depth of water in m

110. Tsunami- Effects
 EXTENSIVE INUNDATION OF COASTAL AREAS
 EXTENSIVE RUN UP OF COASTAL AREAS
 DAMAGE TO COASTAL STRUCTURES
 LOSS OF BUILT ENVIRONMENT
 LOSS OF HUMAN LIFE
 LOSS OF FLORA AND FAUNA
 CHANGES IN WATER QUALITY AND QUANTITY

111. Tsunami 2004 - Comparison of Stats
TSUNAMI TSUNAMI 2004
Earthquake Depth < 50 30 m
Earthquake Magnitude > 7.5 9.1
Wavelength 100 – 200 km 180 km
Velocity 600 – 800 km/hr 750 km/hr
Amplitude 0.3m to 0.6m 0.5m
Period 5 min to 1 hour 45 minutes
Height of Waves 20m to 40m 35m

112. Tsunami Formation
 Tsunamis can be generated when the sea floor suddenly
displaces the overlying water vertically.
 When they occur beneath the sea, the water above the
deformed area is displaced from its equilibrium position.
 Waves are formed as the displaced water mass, acting under
the force of gravity, tries to regain equilibrium.
 When large areas of the sea floor elevate or subside, a tsunami
can be created.

113. Tsunami Formation
 As a tsunami leaves the deep ocean and travels toward the
shallow coast, it transforms.
 A tsunami moves at a speed related to the water depth,
therefore the tsunami slows as the water depth decreases.
 The tsunami's energy flux, being dependent on both its wave
speed and wave height, remains nearly constant.
 As a result, the tsunami's speed decreases as it travels into
shallower water, and its height increases.
 When it reaches the coast, it may appear as a rapidly rising or
a series of breaking waves.

114. Tsunami Formation
 As a tsunami reaches the shore, it begins to lose energy .
 It slows down and height increases when approaching shallow
coast
 Tsunamis reach the coast with tremendous amounts of energy.
 Destructive power is due to speed and force with which they
strike the coastal area.
 Tsunamis are stronger and retain height longer than waves
generated by wind.

115. Tsunami – Counter Measures
Coastal Protection Structures (Structural)
(Sea Walls, Bulk Heads , Revetments , Dikes and Leeves, Breakwaters,
Groynes , Jetties and Piers)
Coastal Protection Structures (Non Structural)
(Vegetation Planting, Groundwater Drainage, Beach Nourishment, Sand
Bypassing and Flood Proofing)
Tsunami Early Warning Systems
(Sensor Networks and Communication Infrastructure)
(International and Regional Warning Systems)
Coastal Regulations
(Avoiding Low Lying Coastal Areas for developmental works)
Evacuation Plan

116. GROUND DAMAGE
AND FAILURE
Surface Distortions
Liquefaction
Fissures
Earthquake Fountain
Sand Boils & Mud Flows
Mud Volcano
Landslides & Avalanches
Changes in Surface & Ground Water

117. GROUND DAMAGE
Due to an earthquake, as a result of
passing of seismic waves, the ground or
the surface may be damaged in several
ways.
Fault can cause earthquakes. In turn
earthquakes will also lead to faults. Apart
from these faults, earthquakes are
associated with eight distinct damages to
the ground

118. GROUND DAMAGES
Surface Distortions
Liquefaction
Fissures
Earthquake Fountain
Sand Boils & Mud Flows
Mud Volcano
Landslides & Avalanches
Changes in Surface & Ground Water

119. SURFACE DISTORTIONS
(1) After occurrence of some earthquakes, large
scale changes in topography take place and the
ground surfaces are distorted.
(2) This is most dangerous when it occurs along
the coastlines. When surface distortions happen
at coastlines, there are two possible ways of
damage.
1. Submergence/Subsidence of Coastline
2. Uplift of Coastline

120. SURFACE DISTORTIONS
(3) When coastlines subside or submerge, it is
accompanied by transgression of the sea. In case
they uplift, it is accompanied by regression of the
sea.
(4) Eg. - Due to the Great Indian Ocean Tsunami
of 2004, the Andaman and Nicobar Islands
showed a large amount of subsidence in the
southern islands and equal amount of uplift in the
northern islands. Car Nicobar and Indira Point
subsided by an amount of 3m leading to water
inundating for 3 km while Austen Bridge was
uplifted by 1.5 m and new shallow coral beaches
emerged.

122. LIQUEFACTION
(1) Liquefaction is a phenomenon in which the
strength and stiffness of soil is reduced due to the
ground shaking done by the earthquake.
(2) This takes place when there is water table or
water bearing formations (aquifers) at 10m or less
from the ground surface
(3) Due to liquefaction, the ability of soil to support
the foundation may decrease and may lead to
collapse of structures built on the soil.

123. LIQUEFACTION
(4) Liquefaction of soil tends to cause settlement
of ground. It can also lead to sand boils and mud
flows.
(5) Due to the Great Bihar – Nepal earthquake of
1934, a 200 km long and 60 km wide liquefaction
belt was formed and was named as Slump Belt.
Within the belt, many buildings tilted and many
buildings settled leading to damage of floors and
foundations.

125. FISSURES
(1) After many earthquakes, the grounds show a
long narrow opening due to the process of
splitting or separating of land mass. This is called
fissures.
(2) The fissures can easily develop in alluvial soils
and can tend to be long, wide and deep in such
soils.
(3) The fissures can disturb the underlying soil
and drainage systems. Some fissures have
sprouted water and sand like fountains.

126. FISSURES
(4) If fissures are found in abundance, then it may
lead to other effects like liquefaction, sand boils,
mud flows etc.
(5) Due to the great Indian Ocean Tsunami of
2004, fissures were evident in Andaman Trunk
Road (ATR). The fissures ranged for nearly 200
kilometres in this 300 km long road and was
observed in areas of Baratang, Port Blair and
Mayabunder.

128. EARTHQUAKE FOUNTAINS
(1) When earthquake occurs in areas with plenty
of shallow water, the shaking of ground produces
fountains, sprouts or geysers. This phenomenon
is termed as earthquake fountains.
(2) The earthquake fountains may contain water,
sand, clay, silt and even debris.
(3) The existence of faults in the area or
development of fissures in the area may lead to
earthquake fountains.

129. EARTHQUAKE FOUNTAINS
(4) Due to the Gujarat Earthquake of 2001,
earthquake fountains full of water and soils were
observed in the areas of Bhachau and Amardi.
The fountains rose up to 3m height and emerged
mainly from fissures. The fountains were found in
adjacent locations in a linear stretch for 4 kms.

131. SAND BOILS & MUD FLOWS
(1) Due to an earthquake, when Sand is brought
up into the land and deposited around the
sprouted area, it resembles a crater. This
phenomenon is called sand boils. The sand boils
may lead to local flooding and silt deposition.
When the sand boils are full of mud, they are also
referred to as mud flows.
(2) Due to the Gujarat Earthquake of 2001, sand
boils and mud flows were predominant in the
areas adjoining the Rukmavati river.

133. MUD VOLCANO
(1) The term mud volcano or mud dome is used
to refer to volcano like formations created by
young sedimentary soils at plate margins.
(2)This phenomenon will take place only at
destructive plate boundaries. The mud volcanoes
may contain hot water mixed with mud and other
surface deposits.
(3) The Great Indian Ocean Tsunami 2004
caused the eruption of many mud volcanoes in
Baratung Island in Andaman Nicobar area. It
ejected methane gases and the gas plume
created fire and explosions.

135. LANDSLIDES & AVALANCHES
(1) While landslides and avalanches trigger
earthquakes, earthquakes may also induce
landslides and avalanches.
(2)The term landslide describe to a wide variety of
processes that result in downward movement of
slope forming materials with a distinct zone of
weakness. While landslides are formed from solid
rock or soil, Avalanches are formed from snow
and ice.
(3) Lanslides may either be rotational landslides
or translational landslides, based on the
movement of the failure surface.

136. LANDSLIDES & AVALANCHES
(4) The Kashmir earthquake of 2005 had sparked
a rotational landslide in Baramulla and Uri
regions. The same earthquake had sparked a
gigantic translational landslide at Sadhna Pass
(5) In September 2010, an earthquake at
Christchurch, New Zealand triggered more than
12 avalanches at the famous Mountain Hutt.

138. CHANGES IN WATER QUALITY
(1) The severe ground shaking associated with
any earthquake can disturb the ground water and
surface water in a very large area.
(2)The changes in water quality can be noticed by
changes in colour, odour, turbidity, hardness,
oxygen content etc of surface waters. The
groundwaters get filled with clay and silt and
cannot be used for any purpose.
(3) Apart from changing the water quality,
earthquakes reduce the quantity of water through
diversion of surface waters and water level
changes in groundwater,

139. CHANGES IN WATER QUALITY
(4) Due to the Gujarat Earthquake of 2001, the
groundwater wells of Lodai and Tehsil and the
surface waters of Rann of Kutch were heavily
affected and it took more than 5 years to provide
remediation.

141. LAST BUT NOT THE LEAST
The implication of ground damage to built
environment is very huge.
If buildings and structures are built on
damaged grounds, it poses high
vulnerability.
In such cases, the structures should be
avoided or used only after sufficient
ground improvement is done.

143. As a part of mitigation measures, it becomes
necessary to reduce our vulnerability to the most
common natural disaster – earthquakes
Experience in past earthquakes has shown that
many common buildings and public structures
lack basic resistance to earthquake forces.
With improved design and construction, it is
possible to provide more resistance to
seismic/earthquake forces and thereby prevent
damage to structures and thereby to human life.

144. When a new structure is planned, designed
and constructed to withstand earthquakes,
the process is called earthquake resistant
design or aseismic design of structures.
Seismic Retrofitting is the modification of
existing structures to make them more
resistant to seismic activity, ground motion,
or soil failure due to earthquakes

145. Ten simple steps for earthquake resistant design and
constructions are presented in this lecture. Before
that here are the basic things to do during an
earthquake
 1. STAY CALM
 2. INSIDE: STAND IN A DOORWAY, OR CROUCH
UNDER A DESK OR TABLE, AWAY FROM
WINDOWS OR GLASS DIVIDERS
 3. OUTSIDE: STAND AWAY FROM BUILDINGS,
TREES TELEPHONE AND ELECTRIC LINES
 4. ON THE ROAD: DRIVE AWAY FROM
UNDERPASSES/OVERPASSES: STOP IN SAFE AREA
AND STAY IN A VEHICLE.

146. 1. Symmetry and No Eccentricity
While planning and designing a building/structure, great care should be
ensured for the symmetry of loads and structures. If there is eccentricity
in design (when loads do not coincide with centre of mass), then the
earthquake risks are large.
2. As per the Code
The design and construction of the building should be as per the BIS
(Bureau of Indian Standards) codal provision for earthquake resistant
design as given under the code book - IS 1893:1984 Criteria for
Earthquake Resistant Design of Structures

147. 3. SOLVE THE SOIL
The soil on which the proposed building/structure would rest upon should
be thoroughly checked for its shear strength, soil liquefaction, presence
of water bodies etc. The design for the building should be keeping in with
the parameters of the soil
4. GET THE BEST MATERIALS
For the structure, select quality materials – be it concrete, stones, brick,
steel etc. Especially steel having an elongation of above 14% and yield
strength of 415N/mm^2 should be used.

148. 1. Symmetry and No Eccentricity
While planning and designing a building/structure, great care should be
ensured for the symmetry of loads and structures. If there is eccentricity
in design (when loads do not coincide with centre of mass), then the
earthquake risks are large.
2. As per the Code
The design and construction of the building should be as per the BIS
(Bureau of Indian Standards) codal provision for earthquake resistant
design as given under the code book - IS 1893:1984 Criteria for
Earthquake Resistant Design of Structures

149. 5. STOREY IS THE STORY
While planning and designing a building/structure, do avoid weak storeys.
Avoid soft storeys in ground floor, especially at car parks. In a frame, care
should be taken to avoid weak column and strong beam design
6. ENFORCE REINFORCE
The reinforcement design of columns and beams should be done with
clear intention to resist lateral forces. A strong reinforcement design
would go a long way in ensuring stability against seismic forces

150. 7. JUNCTION AND BRACINGS
In the junction of columns and beams, the placement of shear walls
symmetrically in both directions of the buildings must be done.
Alternatively, the provision of cross bracings would also make the
structure stable against earthquakes.
8. POST TENSIONING
This refers to the provision of unbonded post-tensioning high strength
steel tendons to achieve a moment-resisting system that has self-
centering capacity against lateral loads like earthquakes.

151. 9. BASE ISOLATION
Base isolation is a collection of structural elements of a building that
should substantially decouple the building's structure from the shaking
ground thus protecting the building's integrity and enhancing its seismic
performance
10. DAMPING
During earthquake, certain amount of energy is transferred to the
building and the building will dissipate energy either by undergoing large
scale movement or sustaining increased internal strains in elements such
as the building's columns and beams. Both of these eventually result in
varying degrees of damage. So, by equipping a building with additional
devices which have high damping capacity, we can greatly decrease the
seismic energy entering the building, and thus decrease building damage

152. GUJARAT EARTHQUAKE 2001
1. It is called the 2001 Gujarat earthquake or Kutch Earthquake and it occurred on January 26,
2001, at 08:46 AM local time and lasted for over two minutes.
2. The epicentre was about 9 km south-southwest of the Bhachau Taluka of Kutch District of
Gujarat, India.
3. The earthquake reached a magnitude of between 7.6 and 7.7 on the Richter magnitude scale
and had a maximum felt intensity of X (Intense) on the Mercalli intensity scale.
4. The quake killed around 20,000 people, injured another 165,000 and destroyed nearly 400,000
homes. . 21 districts were affected and 600,000 people left homeless. The total property damage
was estimated at 5.5 billion US dollars
5. This was an intraplate earthquake, one that occurred at a distance from an active plate
boundary, so the area was not well prepared. The 2001 Gujurat earthquake was caused by
movement on a previously unknown south-dipping fault, trending parallel to the inferred rift
structures.

153. THE GREAT INDIAN OCEAN TSUNAMI 2004
The 2004 Indian Ocean Tsunami also known as Indonesian tsunami, Sumatra Tsunami or
Boxing Day tsunami. was a tsunami triggered by undersea earthquake that occurred at 04:10
AM(IST) on Sunday, 26 December 2004.
The epicentre of the earthquake was the west coast of Sumatra, Indonesia. The earthquake was
caused by subduction of tectonic plates. With a magnitude of 9.1–9.3, it is the third largest
earthquake ever recorded on a seismograph. The earthquake had the longest duration ever
observed, between 8.3 and 10 minutes
The Tsunami accounted for a killing of over 230,000 people in fourteen countries, and is one of
the deadliest natural disasters in recorded history. Indonesia was the hardest-hit country, followed
by Sri Lanka, India, and Thailand. The total economic damages were evaluated at more than 20
billion US dollars
The risk of famine and epidemic diseases was extremely high immediately following the tsunami
and it posed the biggest ever disaster management challenge.
The entire world came together to offer rehabilitation for the victims affected by the Tsunami.
They were involved in rebuilding homes, children protection, setting up community
centres, providing infrastructure, and establishing means of education and livelihood.