The document discusses earthquakes, including their causes, types of seismic waves produced, measurement on the Richter scale, potential hazards caused by earthquakes like landslides, fires, liquefaction, tsunamis and floods. It also discusses methods of earthquake prediction and safety precautions to take during an earthquake based on one's location.

2. Submitted To:
Sir Fahad Hameed
Submitted By:
Ahmed Younhais Tariq
5th Semester
Evening “B”

4. An earthquake is the result
of a sudden release of
energy in the Earth's crust
that creates seismic waves.
The seismic activity of an
area refers to the
frequency, type and size of
earthquakes experienced
over a period of time.

5. For Example:
If you throw stone in a pond of still
water, series of waves are produced on the
surface of water, these waves spread out in all
directions from the point where the stone
strikes the water similarly, any sudden
disturbances in the earth’s crust may produce
vibrations in the crust which travel in all
directions from point of disturbances.

7. Focus is the point on the fault
where rupture occurs and the
location from which seismic
waves are released.
The epicenter is the point on
the Earth's surface that is directly
above the focus, the point where
an earthquakes or underground
explosion originates.

8. A fault line is the surface
trace of a fault, the line of
intersection between the
fault plane and the Earth's
surface.
A fault scarp is
the topographic expression
of faulting attributed to the
displacement of the land
surface by movement along
faults.

10. The primary cause of an earthquake is faults
on the crust of the earth. The cracks or sudden
slips of the land are known as faults or fault
planes. Some major causes of earthquakes on
basic of its causes are:
 Surface causes.
 Volcanic causes.
 Tectonic causes.

11.  Great explosions, landslides, slips on steep
coasts, dashing of sea
waves, avalanches, railway trains, heavy
trucks, some large engineering projects cause
minor tremors. Some of them are man
made, others are natural.

12.  Volcanic eruptions produce earthquakes.
Earthquakes may precede, accompany and
frequently follow volcanic eruptions. They
are caused by sudden violent displacements
of lava within or beneath the earth crust.

13.  Structural disturbances resulting in the relative
displacements of the parts of the lithosphere is
the main cause of this type of earthquake.
Most of the disastrous earthquakes belong to
this category and occur in areas of great faults
and fractures. Sudden yielding to strain
produced on the rocks of accumulating stress
causes displacements especially along old fault
zones known as great transform faults.

14.  Stresses accumulate on the two sides of the
fault plane and produce strain. The rock
deforms bends and when the stress crosses the
elastic limit, sudden displacement of the two
sides of the fault plane takes place. This results
in a strong blow to the rocks Elastic rebound
and produces tremors.

16. Seismic waves produced
due to earthquake are
basically divided into
two major types:
 Body Waves.
 Surface Waves.

17. Body waves travels through the interior (body) of earth as
they leave the focus. Body waves are further divided into
following types:
 Primary (P) Waves.
 Secondary (S) Waves.

18. Primary waves are high frequency, short-
wavelength, longitudinal waves which can pass through
both solids and liquids which forced to move forwards
and backwards as it is compressed and decompressed.
This produces relatively small displacements of the
ground.
P Waves can be reflected and refracted, and under
certain circumstances can change into S-Waves.

19. Secondary Waves (S-Waves) travel more slowly than P-
Waves and arrive at any given point after the P-Waves.
Like P-Waves they are high frequency, short-wavelength
waves, but instead of being longitudinal they are
transverse. They move in all directions away from their
source, at speeds which depend upon the density of the
rocks through which they are moving. They cannot move
through liquids.

20. Surface waves travels parallel to the earth’s surface and
these waves are slowest and most damaging. Surface
waves are divided into
following types:
• Love waves.
• Rayleigh waves.

21. Love waves cause horizontal shifting of the earth during
an earthquake. These waves travel with a slower velocity
than P- or S- waves, but faster than Rayleigh waves .
These waves are observed only when there is a low
velocity layer overlying a high velocity layer.

22. Rayleigh waves travel near the surface of solids as they
created close to the epicenter and can only travel through
the outer part of the crust. Due to these waves the ground
is made to move in a circular motion, causing it to rise and
fall as visible waves move across the ground.

24. Earthquakes are basically
divided into two types on the basic
of difference in causes which are
following:
 Tectonic Earthquake.
 Volcanic Earthquake.

25.  Tectonic earthquakes are triggered when the
crust becomes subjected to strain, and
eventually moves. The theory of plate tectonics
explains how the crust of the Earth is made of
several plates, large areas of crust which float
on the Mantle. Since these plates are free to
slowly move, they can either drift towards each
other, away from each other or slide past each
other. Many of the earthquakes which we feel
are located in the areas where plates collide or
try to slide past each other.

26.  Major earthquakes are sometimes occur by a period of
changed activity. This might take the form of more
frequent minor shocks as the rocks begin to move , called
foreshocks , or a period of less frequent shocks as the two
rock masses temporarily 'stick' and become locked
together. Detailed surveys longitudinal features very
slowly become deformed as the pressure builds up in the
rocks, then become noticeably offset when a movement
occurs along the fault. Following the main shock, there
may be further movements, called aftershocks, which occur
as the rock masses 'settle down' in their new positions.
Such aftershocks cause problems for rescue
services, bringing down buildings already weakened by
the main earthquake.

27.  Volcanic earthquakes are far less common than
Tectonic ones. They are triggered by the
explosive eruption of a volcano. Given that not
all volcanoes are prone to violent eruption, and
that most are 'quiet' for the majority of the
time, it is not surprising to find that they are
comparatively rare.
 When a volcano explodes, it is likely that the
associated earthquake effects will be confined
to an area 10 to 20 miles around its base, where
as a tectonic earthquake may be felt around the
globe.

28.  By contrast, volcanoes producing free flowing basic
lava rarely cause earthquakes. The lava flows freely out
of the vent and down the sides of the volcano, releasing
pressure evenly and constantly. Since pressure doesn't
build up, violent explosions do not occur.

30. The intensity and strength of an earthquake is
measured on Richter scale, the scale invented by
Charles Richter California, USA in 1935, which
categories earthquake on the basis of energy
released.

31. Intensity of earthquake on Richter Energy release (amount of TNT):
scale:
1.0 170 Grams
2.0 6 Kilogram
3.0 179 Kilogram
4.0 5 Metric Tons
5.0 179 Metric Tons
6.0 5643 Metric Tons
7.0 179100 Metric Tons
7.5 1 Mega Tons
8.0 564300 Metric Tons

32. Increase in magnitude significantly increase the time of
shaking and potential damage.
Richter Magnitude: Duration of strong ground
shaking ( seconds):
8-8.9 30-90
7-7.9 20-50
6-6.9 10-30
5-5.9 2-50
4-4.9 0-5

34. Landslides:
Earthquakes, along with
severe storms, volcanic
activity, coastal wave
attack, and wildfires, can
produce slope instability
leading to landslides, a
major geological hazard.

35. Shaking and ground
rupture:
Shaking and ground rupture are
the main effects created by
earthquakes, principally resulting
in more or less severe damage to
buildings and other rigid
structures.
Specific local
geological, geomorphological, an
d geostructural features can
induce high levels of shaking on
the ground surface even from
low-intensity earthquakes. This
effect is called site or local
amplification.

36. Fires:
Earthquakes can cause fires
by damaging electrical
power or gas lines, and
sometime it may also become
difficult to stop the spread of
a fire once it has started.
For example, more deaths in
the 1906 San Francisco
earthquake were caused by
fire than by the earthquake
itself.

37. Soil liquefaction:
Soil liquefaction occurs
when, because of the
shaking, water-saturated
granular material (such as
sand) temporarily loses its
strength and transforms from
a solid to a liquid. Soil
liquefaction may cause rigid
structures, like buildings and
bridges, to tilt or sink into the
liquefied deposits. This can be
a destructive effect of
earthquakes.

38. Tsunami:
Tsunamis are long-wavelength
sea waves produced by the
sudden or abrupt movement of
large volumes of water. In the
open ocean the distance between
wave crests can surpass 100
kilometers and the wave periods
can vary from five minutes to
one hour. Such tsunamis travel
600-800 kilometers per hour
(373–497 miles per
hour), depending on water
depth.
Such tsunami cause a huge
destruction to nearby seashores.

39. Floods:
A flood is an overflow of
any amount of water that
reaches land.
Floods may be secondary
effects of earthquakes, if
dams are damaged.
Earthquakes may cause
landslips to dam
rivers, which collapse
and cause floods.

40. Human impacts:
An earthquake may cause
injury and loss of life, road
and bridge damage, general
property damage and
collapse or destabilization
(potentially leading to future
collapse) of buildings. The
aftermath may bring
disease, lack of basic
necessities, and higher
insurance premiums.

42. Earthquake prediction is usually defined as the
specification of the time, location, and magnitude of
a future earthquake within stated limits. Many
methods have been developed for predicting the
time and place in which earthquakes will occur.
Despite considerable research efforts by
seismologists, scientifically reproducible predictions
cannot yet be made to a specific day or month. Major
earthquakes are often followed by reports that they
were predicted, but no claim of a successful
prediction of a major earthquake has survived close
inquiry.

43. But some evidence of upcoming Earthquake are
following:
 Animal Behavior: Unusual and anomalous behavior of
animals is evidence of coming earthquake.
 Water Level in Wells: Water level in wells changes also
produce possibility of an earthquake.
 Foreshocks: Minor shocks before major earthquake.
 Oil Production: Large scale fluctuations of oil from oil
wells are also show a chance of possible coming
earthquake.

44.  Emission of Radon Gas: Radon gas is inert produced by
the decay of uranium . Radon remain within rocks until
some event force it out. So emission of radon gas is evidence
of earthquake.
 Uplifting of Earth surface: Uplifting of earth’s surface
is also use for prediction of earthquake.

46. If you are in a house;
 Don’t use lift for getting down from building.
 Be prepared to move with your family.
If you are in shop, school or office;
 Don’t run for an exit.
 Take cover under a desk/table.
 Move away from window glass.
 Do not go near electric points and cable. Keep away from
weak portion of the building and false ceiling.

47. If you are outside;
 Avoid high buildings, walls, power lines and other
objects that could fall and create block.
 Don’t run through streets.
 If possible, move on to an open area away from hazard
including trees.
If you are in vehicle;
 Stop in a safe and open place.
 Remain inside vehicle.
 Close windows, doors and vents.