1) The document discusses causes, effects, and measurement of earthquakes. It describes how earthquakes are caused by the sudden release of energy from movement of tectonic plates or volcanic activity. 2) Key terms are defined, such as focus, epicenter, and different types of faults. Different types of seismic waves - P, S, Rayleigh, and Love waves - are also explained. 3) Examples are given of major earthquakes, including the 2005 Kashmir earthquake that killed over 80,000 people in Pakistan, India and Afghanistan.

1. Presented by:
MUHAMMAD AFZAL
0225-MPHIL-CHEM-22

2. INTRODUCTION
Earthquake ( also known as quake, tremor or temblor) is the phenomenon
where there is a sudden release of extreme energy from the earth crust
resulting in shaking and displacement of the ground along with the creation of
seismic waves(detail is in coming sections)
Earthquake shaking may cause lose of life and destruction of property.
In strong Earthquake ground shake
violently.
Buildings may fall or sinks into
the soil.

3. TERMS RELATED TO
EARTHQUAKE
Focus(Hypocenter):
Focus is the point in the fault where rupture occurs
and the location from which seismic waves are
released.
Epicenter:
Epicenter is the point on the earth’s surface that is
directly above the focus (the point where an
earthquake or underground explosion originates)
Fault:
A fault is a fracture or zone of fractures between two
blocks of rock.

4. TERMS RELATED TO
EARTHQUAKE
Fault line:
A fault line is a surface trace of a fault, the line of
intersection between the Earth’s surface.
Fault scrap:
A fault scrap is the topographic expression of
faulting attributed to the displacement of the land
surface by movement along faults.

5. CAUSES OF EARTHQUAKE
Primary cause of Earthquake is fault on crust of Earth.
A fault is a fracture or zone of fractures between
two blocks of rock in response to stress.
Classification of Faults:
1.Normal Fault
2.Reverse Fault
A normal fault is one in which the rocks above the
fault plane, or hanging wall, move down relative to the
rocks below the fault plane, or footwall
A reverse fault is one in which the hanging wall moves
up relative to the footwall.

6. 3.Strike slip Fault
When rocks on either side of a nearly vertical fault
plane move horizontally, the movement is called
strike-slip.

7. OTHER CAUSES OF EARTHQUAKE
Tectonic cause:
There are seven major plates:
African, Antarctic, Eurasian, Indo-
Australian, North American, Pacific
and South American
The tectonic plates are always
slowly moving, but they get stuck
at their edges due to friction.
 When the stress on the edge
overcomes the friction, there is an
earthquake that releases energy in
waves that travel through the
earth's crust and cause the shaking
that we feel.

8. Volcanic earthquakes
 Volcanic earthquakes are those
that occur inside volcanoes or
close to them.
 Earthquakes are produced
by vibrations generated by the
movement of magma or other
fluids within the volcano.
Pressure within the system
increases and the surrounding
rock fails, creating small
earthquakes.

9. Volcanic earthquakes

10. Volcanic earthquakes

11. ARTIFICIAL INDUCTION
Earthquakes are sometimes caused by human activities, including;
•The injection of fluids into deep wells,
•The detonation of large underground nuclear explosions,
•The excavation of mines, and the filling of large reservoirs.

12. EFFECTS OF EARTHQUAKES
Earthquakes have varied effects, including changes in geologic features,
damage to man-made structures, and impact on human and animal life.
Most of these effects occur on solid ground, but, since most earthquake foci are
actually located under the ocean bottom, severe effects are often observed along
the margins of oceans.
Surface phenomena
Earthquakes often cause
dramatic geomorphological changes,
including ground movements—either vertical
or horizontal—along geologic fault traces;
rising, dropping, and tilting of the ground
surface; changes in the flow of groundwater;
liquefaction of sandy ground; landslides;
and mudflows.

13. Following certain
earthquakes, very long-
wavelength water waves in
oceans or seas sweep
inshore. More properly called
seismic sea waves
or tsunamis (tsunami is a
Japanese word for “harbour
wave”), they are commonly
referred to as tidal waves,
although the attractions of
the Moon and Sun play no
role in their formation.
Tsunamis

14. Earthquake in Pakistan
On October 8, 2005, a magnitude 7.6 earthquake shook the Kashmir region (a disputed
territory controlled in part by Pakistan and India), along with sections of Pakistan, India and
Afghanistan.
More than 80,000 people perished as a result of the quake, while an estimated 4
million others were left homeless.
The epicenter of this earthquake was located
around Muzaffarabad, a city approximately 65
miles northeast of the Pakistani capital,
Islamabad. The hypocenter was estimated to
be 12 miles below the earth's surface. The
duration of 60 seconds was twice that of an
average earthquake.

15. The study of earthquake
Seismic waves
Seismic waves are waves that travel through or over Earth.
They are usually generated by movements of the Earth's
tectonic plates (earthquakes) but may also be caused by
explosions, volcanoes and landslides. They can tell us much
about the Earth's structure.
Earthquakes generate four principal types of elastic waves;
two, known as body waves, travel within the Earth, whereas
the other two, called surface waves, travel along its surface.

16. P-Waves
There are Four basic types of seismic waves
•P-waves,
•S-waves
•Rayleigh Waves and
•Love waves.
P-waves and S-waves are collectively called body waves.
TYPES OF SEISMIC WAVES
P-waves, also known as primary waves or pressure waves,
travel at the greatest velocity through the Earth.
They propagate through a material by alternately
compressing and expanding the medium.

17. P-Waves

18. S-Waves
S-waves, also known as secondary waves, shear waves or shaking waves,
are transverse waves that travel slower than P-waves.
In this case, particle motion is perpendicular to the direction of wave
propagation.

19. Love-Waves
Love waves, named after the
British seismologist A.E.H. Love,
who first predicted their existence.
They are propagated when the
solid medium near the surface has
varying vertical elastic properties.
Displacement of the medium by
the wave is entirely perpendicular
to the direction of propagation and
has no vertical or longitudinal
components

20. Rayleigh waves
Named after the British
physicist Lord Rayleigh, who first
mathematically demonstrated their
existence.
Rayleigh waves travel along the free
surface of an elastic solid such as the
Earth.
Their motion is a combination
of longitudinal compression and
dilation that results in an elliptical
motion of points on the surface.
Of all seismic waves, Rayleigh
waves spread out most in time,
producing a long wave duration on
seismographs.

21. After shocks
Aftershocks are a sequence of
earthquakes that happen after a
larger mainshock on a fault.

22. SEISMOGRAPH
Seismographs are instruments used to record the
motion of the ground during an earthquake.
 They are installed in the ground throughout the world
and operated as part of a seismographic network.
A seismograph is securely mounted onto the surface
of the earth so that when the earth shakes, the entire
unit shakes with it EXCEPT for the mass on the spring,
which has inertia and remains in the same place.
The recording device on the mass records the
relative motion between itself and the rest of the
instrument, thus recording the ground motion.

23. SEISMOGRAM
A seismogram is a graph output by a seismograph. It is a record of the
ground motion at a measuring station as a function of time.

24. Magnitude
Earthquake magnitude is a measure of the “size,” or amplitude, of the seismic
waves generated by an earthquake source and recorded by seismographs.
In 1935 the American seismologist Charles F. Richter set up a magnitude scale of
earthquakes as the logarithm to base 10 of the maximum seismic wave amplitude (in
thousandths of a millimetre) recorded on a standard seismograph (the Wood-
Anderson torsion pendulum seismograph) at a distance of 100 km from the
earthquake epicentre.

25. Richter scale of earthquake magnitude
Magnitude
level
Category Effects Earthquakes per year
less than 1.0
to 2.9
micro
generally not felt by people, though recorded on
local instruments
more than 100,000
3.0–3.9 minor felt by many people; no damage 12,000–100,000
4.0–4.9 light felt by all; minor breakage of objects 2,000–12,000
5.0–5.9 moderate some damage to weak structures 200–2,000
6.0–6.9 strong moderate damage in populated areas 20–200
7.0–7.9 major serious damage over large areas; loss of life 3–20
8.0 and higher great
severe destruction and loss of life over large
areas
fewer than 3