1. Earthquake

2. Outline
What is an Earthquake?
Cause of Earthquake
Measuring Earthquake
Earthquake’s Epicenter Located?
Size and Strength of an Earthquake Measured?
Destruction from Earthquake
Earthquake Prediction
Remedial Measures
Case Studies

3. Earthquakes
What Is an Earthquake?
• Focus or hypocenter is the point within Earth where the
earthquake starts.
• Epicenter is the location on the surface directly above
the focus.
 An earthquake is the vibration of Earth
produced by the rapid release of energy
 Focus and Epicenter

4. Focus, Epicenter, and Fault

5. •At the Earth's surface, earthquakes manifest themselves by
shaking and sometimes displacement of the ground. When a
large earthquake epicenter is located offshore, the seabed may
be displaced sufficiently to cause a tsunami. Earthquakes can
also trigger landslides, and occasionally volcanic activity.
•Earthquakes are caused mostly by rupture of geological faults,
but also by other events such as volcanic activity, landslides, mine
blasts, Meteorite strike and nuclear tests.

6. Types Of Earth Quakes
Shallow Focus EQ
Earthquakes occurring at a depth of less than 10 km are classified as
'shallow-focus' earthquakes.
Intermediate Focus EQ
Those with a focal-depth between 70 and 300 km are commonly
termed 'mid-focus' or 'intermediate-depth' earthquakes.
Deep Focus EQ
•In subduction zones, where older and colder oceanic crust descends beneath
another tectonic plate, deep-focus earthquakes may occur at much greater depths
(ranging from 300 up to 700 kilometers).
•These seismically active areas of subduction are known as Wadati-Benioff zones.
•Deep-focus earthquakes occur at a depth where the subducted lithosphere
should no longer be brittle, due to the high temperature and pressure. A possible
mechanism for the generation of deep-focus earthquakes is faulting caused by
olivine undergoing a phase transition into a spinel structure.

7. Cause of Earthquakes
 Elastic Rebound Theory
Most earthquakes are produced by the rapid release of
elastic energy stored in rock that has been subjected to
great forces.
When the strength of the rock is exceeded, it suddenly
breaks, causing the vibrations of an earthquake.
Rupture occurs and the rocks quickly rebound to an un
deformed shape
Energy is released in waves that radiate outward from the
fault

8. Three Types of Faults
Strike-Slip
Thrust
Normal

9. Slippage along a Fault

10. Elastic Rebound Theory

11. Strike-slip Fault Example

12. Normal Fault Example
Dixie Valley-Fairview Peaks, Nevada earthquake
December 16, 1954

13. Thrust Fault Example

14. Thrust Fault Example

15. Earthquake Effects - Ground Shaking
Northridge, CA 1994

16. Earthquake Effects -
Ground Shaking
Northridge, CA 1994

17. Earthquake Effects - Ground Shaking
KGO-TV News ABC-7
Loma Prieta, CA 1989

18. Earthquake Effects - Ground Shaking
Kobe, Japan 1995

19. Earthquake Effects - Ground Shaking
Kobe, Japan 1995

20. Earthquake Effects - Surface Faulting
Landers, CA 1992

21. Earthquake Effects - Liquefaction
Source: National Geophysical Data Center
Niigata, Japan 1964

22. Earthquake Effects - Landslides
Turnagain Heights, Alaska,1964 (upper left inset);
Santa Cruz Mtns, California , 1989
Source: National Geophysical Data Center

23. Earthquake Effects - Fires
KGO-TV News ABC-7
Loma Prieta, CA 1989

24. Earthquake Effects - Tsunamis
Photograph Credit: Henry Helbush. Source: National Geophysical Data Center
1957 Aleutian Tsunami

25. Margalla Tower,Islamabad

26. Total Slip in the M7.3 Landers Earthquake
Rupture on a Fault

27. 
Depth
Into the
earth
Surface of the earth
Distance along the fault plane
100 km (60 miles)
Slip on an earthquake fault
START

28. Slip on an earthquake fault
Second 2.0

29. Slip on an earthquake fault
Second 4.0

30. Slip on an earthquake fault
Second 6.0

31. Slip on an earthquake fault
Second 8.0

32. Slip on an earthquake fault
Second 10.0

33. Slip on an earthquake fault
Second 12.0

34. Slip on an earthquake fault
Second 14.0

35. Slip on an earthquake fault
Second 16.0

36. Slip on an earthquake fault
Second 18.0

37. Slip on an earthquake fault
Second 20.0

38. Slip on an earthquake fault
Second 22.0

39. Slip on an earthquake fault
Second 24.0

40. Causes
• While most earthquakes are caused by
movement of the Earth's tectonic plates.
• Earthquakes are caused mostly by rupture of
geological faults, but also by other events such
as volcanic activity, landslides.
• Violent Volcanic eruptions may cause E.Q.
• If ,Meteorite strikes the earth.

41. • While most earthquakes are caused by movement of the Earth's tectonic
plates, human activity can also produce earthquakes. Four main activities
contribute to this phenomenon: storing large amounts of water behind a
dam (and possibly building an extremely heavy building), drilling and
injecting liquid into wells, and by coal mining and oil drilling.
• Perhaps the best known example is the 2008 Sichuan earthquake in
China's Sichuan Province in May; this tremor resulted in 69,227 fatalities
and is the 19th deadliest earthquake of all time. The Zipingpu Dam is
believed to have fluctuated the pressure of the fault 1,650 feet (503 m)
away; this pressure probably increased the power of the earthquake and
accelerated the rate of movement for the fault.
• The greatest earthquake in Australia's history is also claimed to be
induced by humanity, through coal mining. The city of Newcastle was built
over a large sector of coal mining areas. The earthquake has been
reported to be spawned from a fault that reactivated due to the millions
of tonnes of rock removed in the mining process.

42. Bigger Faults Make Bigger Earthquakes
1
10
100
1000
5.5 6 6.5 7 7.5
Magnitude
Kilometers
8

43. Bigger Earthquakes Last a Longer Time
1
10
100
5.5 6 6.5 7 7.5 8
Magnitude
Seconds

44. What Controls the Level of Shaking?
• Magnitude
More energy released
• Distance
Shaking decays with distance
• Time Span
How long E.Q stays in a locality
• Local soils/rock conditions
Amplify the shaking
M5
M6
M7

45. Cause of Earthquakes
• An aftershock is a small earthquake that
follows the main earthquake. Continuing
adjustment of position results in aftershocks.
• A foreshock is a small earthquake that often
precedes a major earthquake.
 Aftershocks and Foreshocks

46. Earthquake Waves
Measuring Earthquakes
 Seismographs are
instruments that
record earthquake
waves.
 Seismograms are
traces of amplified,
electronically
recorded ground
motion made by
seismographs.

47. Seismograph

49. At convergent boundaries, focal depth increases along a
dipping seismic zone called a Benioff zone

50. Seismotectotics
Seismotectonics is the study of the relationship
between the earthquakes, active tectonics and individual
faults of a region.
It seeks to understand which faults are responsible for
seismic activity in an area by analyzing a combination of
regional tectonics, recent instrumentally recorded events,
accounts of historical earthquakes and geomorphologic
evidence.
This information can then be used to quantify the
seismic hazard of an area.

65. Measuring Earthquakes
What are Seismic Waves?
Response of material to the arrival of energy fronts
released by rupture
Body Waves: P and S waves
Surface Waves: R and L waves

66. Body Waves: P and S waves
• Body waves
– P or primary waves
• fastest waves
• travel through solids,
liquids, or gases
• compressional wave,
material movement is
in the same direction
as wave movement
– S or secondary waves
• slower than P waves
• travel through solids
only
• shear waves - moves
material
perpendicular to
wave movement

67. Surface Waves: R and L waves
• Surface Waves
– Travel just below or along the ground’s surface
– Slower than body waves; rolling and side-to-side
movement
– Especially damaging to buildings

68. Seismic wave behavior
– P waves arrive first, then S waves, then L and R
– Average speeds for all these waves is known
– After an earthquake, the difference in arrival times at a
seismograph station can be used to calculate the distance
from the seismograph to the epicenter.
How is an Earthquake’s Epicenter Located?

70. How is an Earthquake’s Epicenter
Located?
 Earthquake Distance
• Travel-time graphs from three or more
seismographs can be used to find the
exact
location of an earthquake epicenter.
• A circle where the radius equals the
distance to the epicenter is drawn.
• The intersection of the circles locates
the epicenter
• The epicenter is located using the
difference in the arrival times between P
and S wave recordings, which are related
to distance.
• About 95 percent of the major
earthquakes occur in a few narrow
zones.
 Earthquake Direction
 Earthquake Zones

71. Locating an Earthquake
The farther away a seismograph is from the focus of an earthquake,
the longer the interval between the arrivals of the P- and S- waves

72. How is an Earthquake’s Epicenter
Located?
 Earthquake Distance
• Travel-time graphs from three or more
seismographs can be used to find the
exact
location of an earthquake epicenter.
• A circle where the radius equals the
distance to the epicenter is drawn.
• The intersection of the circles locates
the epicenter
• The epicenter is located using the
difference in the arrival times between P
and S wave recordings, which are related
to distance.
• About 95 percent of the major
earthquakes occur in a few narrow
zones.
 Earthquake Direction
 Earthquake Zones

73. How is an Earthquake’s Epicenter
Located?

75. Material P wave Velocity (m/s) S wave Velocity (m/s)
Air 332
Water 1400-1500
Petroleum 1300-1400
Steel 6100 3500
Concrete 3600 2000
Granite 5500-5900 2800-3000
Basalt 6400 3200
Sandstone 1400-4300 700-2800
Limestone 5900-6100 2800-3000
Sand (Unsaturated) 200-1000 80-400
Sand (Saturated) 800-2200 320-880
Clay 1000-2500 400-1000
Glacial Till (Saturated) 1500-2500 600-1000

76. Size and Strength of an Earthquake
Measured?
 Historically, scientists have used two different
types of measurements
 intensity
 magnitude

77. How are the Size and Strength of an Earthquake Measured?
• Modified Mercalli Intensity Map
– 1994 Northridge, CA earthquake,
magnitude 6.7
• Intensity
– subjective
measure of the
kind of damage
done and
people’s
reactions to it
– Iso-seismal lines
identify areas of
equal intensity

78. Modified Mercalli Scale
I. Instrumental Not felt except by a very few under especially favorable conditions.
II. Feeble Felt only by a few persons at rest, especially on upper floors of buildings. Delicately suspended objects
may swing.
III. Slight Felt quite noticeably by persons indoors, especially on the upper floors of buildings. Many do not
recognize it as an earthquake. Standing motor cars may rock slightly. Vibration similar to the passing of a
truck. Duration estimated.
IV. Moderate Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors
disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars
rocked noticeably. Dishes and windows rattle.
V. Rather Strong Felt by nearly everyone; many awakened. Some dishes and windows broken. Unstable objects
overturned. Clocks may stop.
VI. Strong Felt by all; many frightened and run outdoors, walk unsteadily. Windows, dishes, glassware broken; books
off shelves; some heavy furniture moved or overturned; a few instances of fallen plaster. Damage slight.
VII. Very Strong Difficult to stand; furniture broken; damage negligible in building of good design and construction; slight to
moderate in well-built ordinary structures; considerable damage in poorly built or badly designed
structures; some chimneys broken. Noticed by persons driving motor cars.
VIII. Destructive Damage slight in specially designed structures; considerable in ordinary substantial buildings with partial
collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments,
walls. Heavy furniture moved.
IX. Ruinous General panic; damage considerable in specially designed structures, well designed frame structures
thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off
foundations.
X. Disastrous Some well built wooden structures destroyed; most masonry and frame structures destroyed with
foundation. Rails bent.
XI. Very Disastrous Few, if any masonry structures remain standing. Bridges destroyed. Rails bent greatly.
XII. Catastrophic Total damage - Almost everything is destroyed. Lines of sight and level distorted. Objects thrown into the
air. The ground moves in waves or ripples. Large amounts of rock may move.

79. How are the Size and Strength of an Earthquake Measured?
• Magnitude
– Richter scale
measures total
amount of energy
released by an
earthquake;
independent of
intensity
– based on Amplitude
of the largest wave
produced by an
event is corrected
for distance and
assigned a value on
an open-ended
logarithmic scale
Each unit of Richter magnitude equates to
roughly a 32-fold energy increase
Does not estimate adequately the size of
very large earthquakes

80. Size and Strength of an Earthquake
Measured?
 Momentum Magnitude
• Derived from the amount of displacement that
occurs along the fault zone
• Moment magnitude is the most widely used
measurement for earthquakes because it is the
only magnitude scale that estimates the energy
released by earthquakes.
• Measures very large earthquakes
(surface area of fault) x (avg. displacement along
fault) x (rigidity of rock)

81. Earthquake Magnitudes

82. Some Notable Earthquakes

83. TSUNAMI
A tsunami (plural: tsunamis or tsunami; from Japanese: , lit. "harbor
wave" English pronunciation: or also called a tsunami wave train, and
at one time incorrectly referred to as a tidal wave, is a series of water
waves caused by the displacement of a large volume of a body of water,
usually an ocean, though it can occur in large lakes.

84. Causes
Earthquakes, volcanic eruptions and other underwater explosions (including
detonations of underwater nuclear devices), landslides and other mass
movements, meteorite ocean impacts or similar impact events, and other
disturbances above or below water all have the potential to generate a tsunami.
Some meteorological conditions, such as deep depressions that cause tropical
cyclones, can generate a storm surge, called a meteo-tsunami, which can raise
tides several meters above normal levels. The displacement comes from low
atmospheric pressure within the centre of the depression. As these storm surges
reach shore, they may resemble (though are not) tsunamis, inundating vast areas
of land.
There have been studies and at least one attempt to create tsunami
waves as a weapon. In World War II, the New Zealand Military Forces
initiated Project Seal which attempted to create small tsunamis with
explosives in the area of today's Shakespear Regional Park; the attempt
failed.

90. If the first part of a tsunami to reach land is a trough—
called a drawback—rather than a wave crest, the water
along the shoreline recedes dramatically, exposing normally
submerged areas.
A drawback occurs because the water propagates outwards
with the trough of the wave at its front. Drawback begins
before the wave arrives at an interval equal to half of the
wave's period.
Drawback can exceed hundreds of metres, and people
unaware of the danger sometimes remain near the shore to
satisfy their curiosity or to collect fish from the exposed
seabed.

93. Intensity scales
The first scales used routinely to measure the intensity of tsunami
were the Sieberg-Ambraseys scale, used in the Mediterranean Sea and
the Imamura-Iida intensity scale, used in the Pacific Ocean.
The latter scale was modified by Soloviev, who calculated the
Tsunami intensity I according to the formula
I= ½ + Log2 H av
where H is the average wave height along the nearest coast. This
scale, known as the Soloviev-Imamura tsunami intensity scale, is used
in the global tsunami catalogues compiled by the NGDC/NOAA and
the Novosibirsk Tsunami Laboratory as the main parameter for the
size of the tsunami.

94. Magnitude scales
The first scale that genuinely calculated a magnitude for a
tsunami, rather than an intensity at a particular location was
the ML scale proposed by Murty & Loomis based on the
potential energy.
Difficulties in calculating the potential energy of the tsunami
mean that this scale is rarely used.
Abe introduced the tsunami magnitude scale , calculated
from,
Mt= a log h + b log R = D
where h is the maximum tsunami-wave amplitude (in m)
measured by a tide gauge at a distance R from the epicenter,
a, b & D are constants used to make the Mt scale match as
closely as possible with the moment magnitude scale.

95. The Economics and Societal Impacts of EQs
Damage in Oakland, CA, 1989• Building collapse
• Ground failure /
Liquefaction
• Tsunami
• Fire

96. Seismic Vibrations
Destruction from Earthquakes
The damage to buildings and other structures
from earthquake waves depends on
several factors.
 the intensity
 duration of the vibrations
 the nature of the material on which the
structure is built
 the design of the structure.

97. Significant Causes of Infrastructure Damage
Engineered
(Institutional Buildings)
• Quality of construction and
construction materials
• Lack of seismic considerations
• Lack of monitoring
• Building codes
• Governance weakness
Non-Engineered
(Private Buildings/Homes)
• Lack of awareness about
seismically resistant design
• Settling of structures
• Aspiration to modernize with
insufficient knowledge of safe
construction
• Cost

99. Seismic Vibrations
Destruction from Earthquakes
 Liquefaction
• Saturated material turns fluid
• Underground objects may
float to surface

101. Tsunamis: the Japanese word for “seismic sea wave”
Destruction from Earthquakes
 Cause of Tsunamis
• A tsunami triggered by an earthquake occurs where a slab
of the ocean floor is displaced vertically along a fault.
• A tsunami also can occur when the vibration of a quake
sets an underwater landslide into motion.
Although tsunamis travel quickly, there is sufficient time to
evacuate all but the area closest to the epicenter.

102. Other Dangers
Destruction from Earthquakes
• With many earthquakes, the
greatest damage
to structures is from
landslides and ground
subsidence, or the sinking of
the ground triggered by
vibrations.
 Landslides
• In the San Francisco earthquake of 1906, most
of the destruction was caused by fires that started when gas and
electrical lines were cut.
 Fire

103. A CO2 fire extinguisher
rated for flammable liquids
and gasses
A chemical foam
extinguisher with
contents.
A chemical foam
extinguisher with
contents.
water extinguisher

104. Can Earthquakes be Predicted?
Earthquake Prediction Programs
– include laboratory and field studies of rocks before, during,
and after earthquakes
– monitor activity along major faults
– produce risk assessments

105. Predicting Earthquakes
• So far, methods for short-range predictions of earthquakes have
not been successful.
 Short-Range Predictions
• Scientists don’t yet understand enough about how and where
earthquakes will occur to make accurate long-term predictions.
 Long-Range Forecasts

106. Remedial Measures
Increase public awareness about hazard risk
management.
Build capacity of professionals and government
officials.
 Safe building practices and earthquake
resistant design.
Develop and enforce simple building codes for
rural and peri-urban areas.

107. Seismic Microzonation
• Seismic microzonation is defined as the
process of subdividing a potential seismic or
earthquake prone area into zones with respect
to some geological and geophysical
characteristics of the sites such as ground
shaking, liquefaction susceptibility, landslide
and rock fall hazard, earthquake-related
flooding, so that seismic hazards at different
locations within the area can correctly be
identified.

109. • Microzonation provides the basis for site-specific risk
analysis, which can assist in the mitigation of
earthquake damages.
• Dynamic characteristics of site such as predominant
period, amplification factor, shear wave velocity,
standard penetration test values can be used for
seismic microzonation purpose.
• On the basis of these information, we review our
construction design according to seismic hazards, and
take preventive measures for stability of structures.

110. Earthquake Preparedness
• Earthquake preparedness refers to a variety of
measures designed to help individuals, businesses, and
local and state governments in earthquake prone areas
to prepare for significant earthquakes.
Before Earth Quake
• Retrofitting and earthquake resistant designs of new
buildings and lifeline structures (e.g. bridges, hospitals,
power plants).
• We should have response doctrines for state and local
government emergency services.
• We should train common people by media about
Preparedness plans for E.Q.

111. During Earth Quake
• Drop to the ground
• Take Cover by getting under a sturdy table or other piece of furniture.
• Hold on until the shaking stops.
• If You Are Inside
• Kneel under a desk, table, or bench. If there aren’t enough sturdy pieces
of
• furniture to get under, kneel next to an interior walls but away from
windows,
• overhead light fixtures, and tall pieces of furniture that might fall over.
• Stay under cover until the shaking stops (at least one minute). Face away
• from windows, and bend your head close to your knees.
• Hold on to the table leg or desk (a few inches above the ground to avoid
• pinching fingers). Cover your eyes with your other hand. If your “shelter”
• moves, move with it. If you don’t have a “shelter” to hang on to, clasp
your
• hands on the back of your neck to protect your face.

112. If You Are Outside
• Move into the open, away from buildings,
fences, trees, tall playground
• equipment, utility wires, and street lights.
• • Kneel or sit on the ground and cover your
head and face with your
• hands.
• • Once in the open, stay there until the
shaking stops.

113. What You Can Do After an Earthquake
• Is it safe to move in ?
• Once the shaking has stopped, look around for possible hazards to
determine if it is safe for you to move before getting up and helping
others. If time permits and there is a small fire that can be put out
with the fire extinguisher, do that.
• 2. If you are inside, decide whether to evacuate or stay put.
• Any of the following require immediate evacuation.
• Fire, damage to structure, a gas leak, or hazardous materials spill.
• In some situations, you may choose not to evacuate or to delay
evacuation.
• For example, if there is a slight shaking with no apparent damage and
another hazard such as severe weather, it may be more dangerous to
move children outside.
• If you smell gas or hear a blowing or hissing noise, open a window and
then quickly leave with the children, and shut the gas off at the outside
main meter.

114. • you must evacuate immediately (because of fire,
severe damage to structure, gas leak, or
hazardous materials spill), check all children and
adults for injuries and give first aid for injuries.
• As time permits, you may need to turn off
utilities such as gas, electricity, and water.
• If electrical wires are crackling inside, shut off the
gas first, then turn off the master electrical
switch.

115. CASE STUDIES
Kashmir Earth Quake
Chile Earth Quake

116. Kashmir Earthquake
8th October 2005
7.6-magnitude
earthquake took place on
Saturday 8th October at
08:25 local time.
The epicentre was
Muzzaffarabad the capital
of the Pakistan
administered region of
Kashmir, 80km north-east
of Islamabad.
It was followed by 20
powerful aftershocks

117. How did the earthquake occur
The earthquake in
Pakistan is the result of
India's long-term,
gradual, geological
movement north into
Asia at a speed of five
centimetres a year - a
millimetre per week.
Plate Boundary ???
http://news.bbc.co.uk/1/hi/world/south_asia/4322582.stm

119. Discovering Earth’s Composition
Earth’s Layered Structure
 Mantle
 Crust
• Early seismic data and drilling technology indicate that the
continental crust is mostly made of lighter, granitic rocks.
• Composition is more speculative.
• Some of the lava that reaches Earth’s surface comes from
asthenosphere within.
 Core
• Earth’s core is thought to be mainly dense iron and nickel, similar
to metallic meteorites. The surrounding mantle is believed to be
composed of rocks similar to stony meteorites.

120. Thanks
??......