1. Earthquake-a tragedy to life
and property
• Topic - Earthquake
• Academic year - 2012-13
• Formative 2nd –
Summative1st
• Group - 1st
2. What is Earthquake ?
• An earthquake (also known as
a tremor or temblor) is the
result of a sudden release of
energy in the Earth's crust that
creates seismic waves
• The effects of earthquake
vary upon the magnitude and
intensity. Earthquakes occur
every now and then all round
the world, except in some
places where earthquakes
occur rarely. The devastation
of cities and towns is one of
the effects of earthquake.
• Landslides, Avalanches, Tsuna
mi(Tsu- harbour,Nami-
waves), Volcanoes are also
caused by movement of
earthquakes. Huge rocks come
tumbling down the mountains
sometimes blocking the path
of rivers. This can cause floods.
Houses are broken down by
earthquakes.
3. Causes of Earthquake
Earthquakes are caused by sudden release of energy
in rocks. Plates in the form of rocks are moving very
slowly and earthquake occur when moving plates
grind and scrape against each other. The point at
which an earthquake originates is the focus or
hypocenter and the point on the earth’s surface;
directly above this is epicenter. The study of
earthquake is called seismology.
4. Seismometers- The measurment of
earthquake
Earthquakes can be recorded by seismometers
up to great distances, because seismic waves
travel through the whole Earth's interior. The
absolute magnitude of a quake is
conventionally reported by numbers on the
Moment magnitude scale (formerly Richter
scale, magnitude 7 causing serious damage
over large areas).
5. What are seismic waves?
Every tremor produces different types of
seismic waves, which travel through rock with
different velocities:
• Longitudinal P-waves (shock- or pressure
waves)
• Transverse S-waves (both body waves)
• Surface waves — (Rayleigh and Love waves)
6. Body and Surface 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 - move
material perpendicular to
wave movement
• 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
• Body Waves: P and S
waves
• Surface Waves: R and L
waves
8. • The point of disturbance below the surface
of the Earth is called, FOCUS
9. Tectonic plates
• There are 7 large and 12 small such plates which
are in continuous distinctive types of
boundaries, that is :
convergent boundaries : where plates push
each other and one plate slides down the
other one.
divergent boundaries: where plates pull
away from each other.
• transformed boundaries :
• Earthquake occur due to several causes such as
volcanic eruption, etc. but the plate tectonic
theory is the most convincing and widely accepted
12. Seismological Zone
Depending upon the frequency and intensity of the
earthquakes, the whole country can be divided into
three broad seismological zones
Himalayan zone
The area s most prone to earthquake in India is
the Fold Mountains ranges of the Himalayan zone. The
states of Jammu and Kashmir, Himachal Pradesh,
Uttaranchal, Bihar, the Bihar- Nepal border and north
eastern states.
The earthquakes in these zones are primarily
due to plate tectonics. The region along the Himalayas
where two plates meet is highly earthquake prone and
hence known as the zone of maximum intensity
14. The peninsular zone
The peninsular India has presumably
remained a stable landmass and only few
earthquakes have been experienced in this
region. This region is, therefore, called the
zone of minimum intensity. But the sever
earthquakes of Konya (1967), Latur (1993) and
Jabalpur (1997) have raised doubts about the
seismic stability of this landmass
15. Study of Earthquake
• The study of
earthquake waves is
known as
SEISMOLOGY
• The experts who
study the pattern of
earthquakes are
known as
SEISMOLOGISTS
The machine which records the
intensity of earthquake is known as
SEISMOGRAPH
16. Hazardous Effects of
Earthquake
- Loss of life and property
- Damage to infrastructure
- Topographical changes
- Damage to transport system i.e. roads, railways,
highways, airports, marine.
- Chances of fire short-circuit.
- Chances of Floods – Dams and Embankments can
develop cracks
- Chances of outburst of epidemic
- Water pipes, sewers are disrupted
- Communications such as telephone wires are damaged.
- Economic activities like agriculture, industry, trade and
transport are severely affected.
19. • Date: 26 January 2001
• Origin line: 08 hrs.46 min. 42.9 sec. IST
• Epicenter: Latitude 23.40° N Longitude 70.28°E
• Magnitude: 7.7
• Focal Depth: 25 kms.
20. Bhuj Earthquake 26th January. 2001
On the morning of January
26, 2001, the Nation’s 52nd Republic
Day, a devastating earthquake
occurred in the and Chennai in the
south. Kutch district of the state
of Gujarat.
The earthquake was felt as far away
as Delhi in the north, Kolkata in the
east Bhuj town and the village
Bhachau, 60 km east of Bhuj, were
21. There were more than 20,000
deaths and 167 Around 300,000
families and at least 3 million
children aged 14 and under were
affected. Around 600,000
people were left homeless. In
the city of Bhuj, more than
3,000 inhabitants of the city
lost their lives; the main
hospital was crushed and close
23. Earthquake safety rules
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, office or theater
• Don’t run for an exit. Stampede could prove fatal
• take cover under a desk/table
• move to corner or side walls
• move away from window glass
• Do not go near electric points and cable. Keep away
from weak portion of the building and false ceiling
24. If you are in high rise building
- take protection under a desk/table
- don’t rush for exits
- stay in the building until the shaking stops
- don’t use elevator
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
25. After an Earthquake
• Keep calm, switch on the transistor radio and obey
instructions
• Keep away from beaches and low banks of river. A
huge wave may sweep in
• Expect aftershocks
• Turn off the water, gas and electricity
• Do not smoke, light match or use a cigarette lighter
• Do not turn on switches there may be gas leak or
short circuit
• If there is any fire, try to put it out or call fire
brigade
26. Earthquake proof building
An earthquake-proof building is
a building that has been built to
survive an earthquake. The
building is built with special
technology that has materials
made in earthquake areas. No
building, however, can be made
100% safe.
27. 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
28. 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
