earthquake

2. MECHANICAL BRANCH
STUDY OF EARTHQUAKE

3. CERTIFICATE
This is to certify that
1. Manish Belvekar(03)
2. Abhishek Bhosle(06)
3. Dinesh Kumar (13)
4. Swapnil Gurav(21)
5. Soham Koli(28)
6. Sagar Suryavanshi(66)
Have satisfactorily completed the Group project entitled “ STUDY OF EARTHQUAKE” in semester V as laid by
university of Mumbai.
Prof.Mrs. Pradnya Prof.V.J.Jog
(Project Guide) (H.O.D of Mechanical Department) 3

4. ACKNOWLEDGEMENT
We have great pleasure in presenting this project title “STUDY OF EARTHQUAKE”. We
would like to take this opportunity to express our deepest gratitude and indebted to those who
contributed their valuable time in helping us to successfully complete our project work.
We would like to express our sincere thanks to Mrs. Pradnya(our project guide) and whole staff
who had distributed their valuable experience, time, knowledge and constant guidance
throughout the whole project. We are extremely obliged to all of them for their guidance
without them this project was not possible.
Last but not the least we would like to express our sincere thanks to all of those who directly or
indirectly help us in our project.

5. INDEX
1. Summary…………………………………………………………….
2. Brief History…………………………………………………………
3. Acknowledgement…………………………………………………...
4. What are Earthquakes ?.....................................................................
5. Elastic Rebound Theory………………………………………….....
6. Focus and Epicenter of an Earthquake…………………………….
7. Occurrence of Earthquake and How often ?..................................
8. Economic and Social Impact of Earthquake……………………...
9. Seismic Waves……………………………………………………….
10. Location of Epicenter of Earthquake ……………………………..
11. Measurement of Size and Strength of Earthquake………………
12. Destructive effects of Earthquake………………………………….
13. Prediction of Earthquake……………………………………………
14. Can Earthquake be controlled ?.......................................................
15. Bibliography…………………………………………………………

6. SUMMARY
An earthquake (also known as a quake, tremor )is the result of a sudden release of
energy in the Earth's crust that creates seismic waves. The seismicity or seismic activity
of an area refers to the frequency, type and size of earthquakes experienced over a
period of time.
Earthquakes are measured using observations from seismometers or on local magnitude
scale refer to as Richter scale At the Earth's surface, earthquakes manifest themselves
by shaking and sometimes displacement of the ground. When the epicenter of a large
earthquake 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, and nuclear tests. An earthquake's
point of initial rupture is called its focus or hypocenter. The epicenter is the point at
ground level directly above the hypocenter.

7. Brief History
 Earthquakes have been recorded as early as 1177 B.C. in China. Of course earthquakes have been a part of myth and
legend since the dawn of man. In Greek Mythology, Posseidon (Neptune in the Roman pantheon) was "God of the
Sea". Yet one of his powers was thought to be that of "earth shaker". As a tsunami is often the result of an
earthquake, this was an appropriate power for a sea god.
 In European history, the earliest recorded earthquake occurred in 580 B.C. In North America the great earthquake of
1811-1812 occurred near New Madrid, Missouri .The magnitude of the quakes are not known, but they
are estimated to have been about 8 on the Richter scale. There were actually three large quakes with aftershocks
between and for months after. The quake was so wide-spread it was felt as far away as Boston .
 The most destructive quake in U.S. history occurred in San Francisco in 1906, it caused the deaths of over 700 people.
The great Alaskan earthquake of 1964 was twice as powerful, but less destructive due to the low population density of
the area struck. The Chilean quake of 1960 was the biggest quake ever recorded. It came in at 9.5 on the Richter scale.
 The study of earthquakes is called seismology. The earliest seismologists were the Chinese who worked hard to record
their quakes in detail. They even developed a means to predict earthquakes by filling a ceramic jar to the brim with
water and leaving it set. If the water overflowed the jar, then an earthquake was imminent. Of course, this means of
prediction was unreliable and uncertain.
 It is thought that some animals may feel vibrations from a quake before humans, and that even minutes before a quake
dogs may howl and birds fly erratically. However, evidence for such sensitivity by animals is purely anecdotal.
 Aristotle was one of the first Europeans to create a theory about the origin of Earthquakes. He thought that they were
the result of heavy winds. Not much more study was concentrated on earthquakes until the mid-1700s when London
was hit by a devastating quake and a tsunami struck Lisbon, Portugal shortly after. John Mitchell in England and Elie
Bertrand in Switzerland began a comprehensive study of the timing and severity of earthquakes.
 Soon scientists from several countries were exchanging observations and theories on earthquakes. In the
1820's Chile became an area of interest to seismologists. After an earthquake there, it was noticed that the elevation of
the coastline had changed. This was substantiated by the Captain of the H.M.S. Beagle, Robert Fitzroy. (The ship also
carried Charles Darwin who was studying the flora and fauna of the coast)
 Since then, seismologists have continued to work at a furious pace, building better instruments, computer
models, theories and forecast to study the causes and effects of earthquakes.

8. What are Earthquakes?
The shaking or trembling caused by the sudden release of energy is called an Earthquake . It is usually
associated with faulting or breaking of rocks . Continuing adjustment of position results in aftershocks.
Earthquakes are the Earth's natural means of releasing stress. When the Earth's plates move against each
other, stress is put on the lithosphere. When this stress is great enough, the lithosphere breaks or shifts.
Imagine holding a pencil horizontally. If you were to apply a force to both ends of the pencil by pushing down
on them, you would see the pencil bend. After enough force was applied, the pencil would break in the
middle, releasing the stress you have put on it. The Earth's crust acts in the same way. As the plates move they
put forces on themselves and each other. When the force is large enough, the crust is forced to break. When the
break occurs, the stress is released as energy which moves through the Earth in the form of waves, which we
feel and call an earthquake.

9. how energy is stored in rocks. ?
 Rocks bend until the strength of the rock
is exceeded
 Rupture occurs and the rocks quickly
rebound to an unreformed shape
 Energy is released in waves that radiate
outward from the fault

10. The point within Earth where faulting
begins is the focus, or hypocenter.
The point directly above the focus on
the surface is the epicenter.

11. Seismographs record
earthquake events
At convergent boundaries,
focal depth increases along a
dipping seismic zone called a
Benioff zone

12. Where Do Earthquakes Occur and How Often?
80% of all earthquakes occur in the circum-Pacific belt most of
these result from convergent margin activity 15% occur in the
Mediterranean-Asiatic belt remaining 5% occur in the
interiors of plates and on spreading ridge centers more than
150,000 quakes strong enough to be felt are recorded each year

13. The Economics and Social Impacts of EQs
Damage in Oakland, CA, 1989
 Building collapse
 Fire
 Tsunami
 Ground failure
 Homelessness
 Disease
 Widespread Hunger

14. What are Seismic Waves?
 Seismic waves are waves of energy that travel through the earth
 Seismic wave fields are measured by a seismograph , geophone , accelerometer.
 Earthquakes create various types of waves with different velocities; when
reaching seismic observatories, their different travel time enables the scientists to
locate the Epicenter .
 The propagation velocity of the waves depends on density and elasticity of the
medium. Velocity tends to increase with depth, and ranges from approximately 2
to 8 km/s in the Earth's crust up to 13 km/s in the deep mantle.
Two types:
 Body waves
 P and S
 Surface waves
 R and L

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

16. Surface Waves: R and L waves
R or Rayleigh wave
 Travel as ripples with motions that are similar to those of waves on the surface of water
 They are slower than body waves, roughly 90% of the velocity of S waves for typical homogeneous elastic media
L or love wave
 Love waves are surface waves that cause circular shearing of the ground
 They usually travel slightly faster than Rayleigh waves, about 90% of the S wave velocity, and have the largest amplitude.

17. How is an Earthquake’s Epicenter Located?
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.

18. How is an Earthquake’s Epicenter Located?
Time-distance graph
showing the average travel
times for P- and S-waves.
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

19. How is an Earthquake’s Epicenter Located?
 Three seismograph stations are needed
to locate the epicenter of an earthquake
 A circle where the radius equals the
distance to the epicenter is drawn
 The intersection of the circles locates
the epicenter

20. How are the Size and Strength of an Earthquake Measured?
Intensity
• subjective measure of the kind of damage done and people’s reactions to it.
• Iso-seismal lines identify areas of equal intensity.

21. 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.
 Amplitude of the largest wave produced by an event is corrected for distance and assigned a value on an open-
ended logarithmic scale.
Modified Mercalli Intensity Map
1994 Northridge, CA
earthquake, magnitude 6.7

22. What are the Destructive Effects of Earthquakes?
Ground Shaking
• Amplitude, duration, and damage increases in poorly consolidated rocks
Landslides and avalanches
• Landslides are a major geologic hazard because they can happen at any place in the world, much
like earthquakes. Severe storms, earthquakes, volcanic activity, coastal wave attack, and wildfires
can all produce slope instability.

23. Can Earthquakes be Predicted?
Earthquake Precursors
 changes in elevation or tilting of land surface, fluctuations in groundwater levels, magnetic
field, electrical resistance of the ground
 seismic dilatancy model
 seismic gaps

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

25. Can Earthquakes be Controlled?
 Graph showing the relationship
between the amount of waste injected
into wells per month and the average
number of Denver earthquakes per
month
 Some have suggested that pumping
fluids into seismic gaps will cause small
earthquakes while preventing large
ones

26. Bibliography
 Donald Hyndman, David Hyndman- Natural Hazards and Disasters
(2nd edition).
 www.wikipedia .com
 www.earthquake info.org
 Kanamori Hiroo- "The Energy Release in Great Earthquakes".
Journal of Geophysical Research.
 "Earthquakes" by Edward J. Tarbuck, Frederick K. Lutgens, and
Dennis Tasa.