A classroom presentation with a case study on earthquake

2. EARTHQUAKE
 Earthquake is defined as the shaking of
Earth’s surface due to any reason which
results in release of large amount of energy.
 Earthquakes are a major cause of concern
for Civil Engineers because the effect of
this disaster is measured in terms of extent
damage.

3. Basic Terms Related to
Earthquake
1. Focus - The point
inside the surface of the
earth from where the
earthquake originates is
the focus or hypocenter.
2. Epicenter- The point
on the earth’s surface
vertically above the focus
is the epicenter.

4. 3. Magnitude – Magnitude is a quantitative measure of
the earthquake size. It is a measure of amount of energy
release during the earthquake. The magnitude of an
earthquake is generally measured on Richter scale.
 A relationship b/w energy released by an earthquake
and its magnitude is given as follows :-
log E = 11.4+1.5M
4. Intensity – Intensity is a qualitative measure of the
earthquake. It is a way of measuring or rating the effects of
an earthquake at different sites.

5. Causes of Earthquake
Earthquakes are primarily caused due to two
reasons:-
1. Natural disturbances
2. Artificial disturbances
Natural disturbances are further divided in
two categories:-
a) Volcanic causes
b) Tectonic causes

6. Natural Disturbances
1. Volcanic causes – Volcanic activity
keeps on taking place in several parts of
the world, it produces sudden out burst or
explosion. These earthquakes are not very
deep and of mild intensity. The damage
caused due to this type of earthquake is
confined within a few kilometers. All
volcanic eruption don’t produce
earthquake.

7. 2. Tectonic Causes-
Tectonic causes are those which occur inside the
earth surface.
According to the theory of plate tectonics, the Crust is made
up of rocks and is divided into many plates. These plates are
constantly in motion in different directions and with
different speeds. These plates have strain energy stored in
them.
The earthquake which occur due to sudden release of strain
energy as a result of sudden slip of fault is called as tectonic
earthquake.
 More than 90% of total earthquakes are because of tectonic
reasons.

8. Artificial Disturbances
Sometimes the surface of earth vibrates due to
man-made or artificial disturbance. These vibration
are very mild and affect the surrounding area.
Some of the artificial disturbances causing earthquakes
are :-
i. Nuclear tests and explosion.
ii. Mining blasts in the mining area.
iii. Large and deep excavations.
iv. A massive landslide along hill slopes caused because
of deforestation.

9. What to do ?
Before an earthquake
During an earthquake
After an earthquake

10. Before an Earthquake
• Place heavier objects on lower shelves to prevent
breakage and personal injury.
• You should have a fire extinguisher, first aid kit.
• Learn how to turn off the gas, water, and
electricity.
• Install latches on cupboard doors to prevent them
from opening.

11. During an
Earthquake
• Stay calm! If you're indoors, stay inside. If you're
outside, stay outside.
• Immediately take a safe location , if inside sit under a
table or desk, if outside come in an open atmosphere.
• Cover the back of your head and your eyes to minimize
injury from flying debris.
• Do not take elevators during an earthquake.

12. After an Earthquake
• Check yourself and others for injuries. Provide first aid for
anyone who needs it.
• Stay out of damaged buildings and damaged area.
• Be careful around broken glass. Wear boots or sturdy shoes
to keep from cutting your feet.
• Check gas, water, electrical lines, and appliances for
damage. If you smell gas or see a broken line, shut off the
main valve. Do not switch on the gas or electricity again
until the power company checks your home.

13. Seismology
The waves generated by the earthquake are called
Seismic waves. The study of earthquake and
seismic waves is called Seismology and the
researchers are called Seismologists.
Seismic waves are divided into two broad
categories:-
1. Body Waves
2. Surface Waves

14. Body Waves
In Body waves the speed decreases with increasing
density of rock and increases with increasing rock
elasticity. Rock elasticity increases faster than density
with depth.
There are two kinds of body waves
1. P-waves
2. S-waves

15. Difference in P waves and S waves
P waves S waves
 The P-waves are called
primary, push or longitudinal
waves.
 They vibrate parallel to the
direction of wave movement.
 They have shortest
wavelength, fastest speed {5-
7 km/s}.
 They can travel through
solid, liquid or gas.
 The S-waves are called
secondary, shock , sheer or
transverse waves.
 They vibrate perpendicular to
the direction of wave
movement.
 They have a medium
wavelength, Their velocity is 3
to 4 km per second.
 They only travel through solids
because liquids and gases have
no sheer strength.

16. Surface Waves
A seismic wave that travels across the surface of the
Earth as opposed to through it.
Surface waves usually have larger amplitudes and longer
wavelengths than body waves, and they travel more
slowly than body waves do.
There are two kinds of Surface waves:-
1. Love waves
2. Rayleigh waves

17. Love Waves and Rayleigh
Waves
Love waves make the ground vibrate at right angles to the
direction of waves . They are a variety of S-waves where
the particles of an elastic medium vibrate transversely to
the direction of wave propagation, with no vertical
components.
Rayleigh waves travel near the earth’s surface and within a
depth of 30-32 kilometers from the surface. These are
called Rayleigh waves after Lord Rayleigh who first
described these waves. Generally slower than Love waves.

18. What is Earthquake
Engineering ?
Earthquake Engineering as a profession in India is a
newly introduced field in academics and industry. Since
60% of Indian geography is declared sensitive to
earthquakes, the role of earthquake engineers proves
vital in building quake resistant structures.
Traditionally, it has been narrowly defined as the study
of the behaviour of structures and geo-structures
subjected to seismic loading, thus considered as a
subset of both structural and geotechnical engineering.

19. Cont..
India was struck with several earthquakes in the
past causing damage to life and property.
Government of India has constituted National
Information Center on Earthquake
Engineering (NICEE). It is the Apex Body of
Government of India on Earthquake Researches
and damage control.

20. Requirements for Earthquake
resistant structure ?
 Tie up the walls, floor, roof, and foundations into a rigid
box that holds together when shaken by a quake.
Provide adequate reinforcement
Column should be placed adjacent to one another to
resist the force due to wind coming from different
directions.
 Structure should be as light as possible.

21. Base isolation
Energy dissipation technique
Sill-anchoring technique

22. Base Isolation
A base isolated structure
is supported by a series of
bearing pads which are
placed between the
building and the building’s
foundation. A variety of
different types of base
isolation bearing pads have
now been developed

23. Energy
Dissipation
Devices
The second of the major
new techniques for
improving the earthquake
resistance of buildings also
relies upon damping and
energy dissipation, but it
greatly extends the damping
and energy dissipation
provided by lead-rubber
bearings.

24.  A sill plate, also known as a
sole plate, is the bottom
horizontal member of a
wall or building to which
the vertical studs will be
attached.
 It does keep the boards
attached to the foundation
during an earthquake
allows a building to move
with its foundation
SILL-ANCHORING TECHNIQUE

25. CASE STUDY:-
GUJARAT EARTHQUAKE
26th Jan, 2001

26. INTRODUCTION TO
GUJARAT
Gujarat, one of the western state in India. Its capital
is Gandhinagar. It has an area of 196,024 km2.
Gujarat is bounded by the Arabian Sea in the west,
by Rajasthan in the north, by Madhya Pradesh in the
east and by Maharashtra in the south and south east.
The best time to visit Gujarat is from October to
March.

27. GUJARAT EARTHQUAKE
26TH JANUARY, 2001
On the morning of January 26, 2001, The nation’s 52nd
Republic Day. A devastating earthquake occurred in the
Kutch district of the state of Gujarat.
The earthquake was felt as far away as Delhi in the
north, Kolkata in the east and Chennai in the south.
Bhuj town and the village Bhachau,60km east of Bhuj
were the worst affected and many other areas of
Gujarat including its state headquarters Ahmedabad,
were badly affected .

30. DAMAGES BY EARTHQUAKE

32. MAJOR DEFECTS OF STRUCTURE
IN GUJARAT
Floating column
Pounding
Soft storey building
Unsymmetry

33. FLOATING COLUMN
When the columnand
shear wall donot
continueup to the
groundbut endat an
upperlevel as shown
in fig.

34. When the roofs of two adjacent
buildings are at diff. levels then
,during Earthquakes ,the
brickworks faces hit against each
other this is calledaspounding.
POUNDING

35. SOFT STOREY IRREGULAR
BUILDING
 Due to the absence
of infill wall in the
groung floor
structure of the
building , it behaves
a separate unit w.r.t
the upper floors and
known as ground
soft story .

36. IRREGULARITIES & UNSYMMETRY
 The building as a wholeor
its various blocks should be
kept symmetrical bout both
the axes .
 A building shouldbe lightas
possible & should besimple
.

37. EFFECTS ON STRUCTRAL
MONUMENTS
 The earthquake
devastated Kutch.
Practically all buildings
and structures of Kutch
were brought down.
 Ahmedabad, Rajkot,
Jamnagar,
Surendaranagar and
Patan were heavily
damaged.

38. EFFECTS ON HUMAN LIFE
 Nearly 19,000 people died.
Kutch alone reported more
than 17,000 deaths.
 1.66 lakh people were
injured. Most were
handicapped for the rest
of their lives.
 The dead included 7,065
children (0-14 years) and
9,110 women.
 There were 348 orphans
and 826 widows.