The document provides a comprehensive overview of earthquakes, including their definitions, types, causes, and effects, as well as information on seismic zones in Bangladesh. It emphasizes the significant earthquake risks faced by Dhaka and recommends preventive designs and safety measures for earthquake protection. Furthermore, it includes statistics on recent earthquakes and highlights key historical earthquakes around the world.

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2. Presentation
Engineering Geology & Geomorphology
CEN-223
Instructor
Anisuzzaman Khan
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3. Group Name
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4. Topic
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5. Group Members
Md. Saddam
Husain
ID# 12206023
Md. Hasan
Shahariar
ID#12206013
Md. Shakkik
Zunaed
ID#12206004
Arun Chandra
Acharjee
ID#12206066
Md. Oliullah
Sheik
ID#12206067
Md. Shariful
Haque Robin
ID#12206049
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6. Contents
Topic Topic
What is Earthquake Major Earthquakes Zone in the World
The Focus and Epicenter of an Earthquake Tsunami
Types of Earthquake Earthquakes Zone in Bangladesh
Elastic Rebound Theory Last 2 Years Earthquake Statistic in
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Bangladesh & Places Near Bangladesh
Seismic Waves Earthquake and Dhaka City
Faults Earthquake Preventive Design
How does earthquake occurs Effect of Earthquake
The Seismograph Positive Effects of Earthquake
The Richter Scale Basic Recommendations for Earthquake
Protection

7. What is Earthquake?
 A natural vibration of the
ground or the earth crust
produced by forces is
called earthquake or
seismic forces.
 An earthquake is what
happens when two
blocks of the earth
suddenly slip past one
another.
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8. The Focus and Epicenter of an Earthquake
•The point within Earth
where faulting begins is the
focus
•The point directly above the
focus on the surface is the
epicenter
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9. Types of Earthquake
An earthquake, simply defined as the shaking of the earth’s
surface. On the basis of depth of focus, earthquakes are
classified into three types. Following are the three types of
earthquakes:
Types Depth of focus (km)
Shallow Earthquake 60
Intermediate Earthquake 60-300
Deep Earthquake > 300
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10. Elastic Rebound
Theory
Rocks bend under stress
while storing elastic energy.
When the strain in the rocks
exceeds their strength,
breaking will
occur along the fault.
Stored elastic energy is
released as the earthquake.
Rocks "snap back”, or
rebound to their original
condition.
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11. Seismic Waves
 Two types:
Body waves Surface waves
P Wave S Wave R Wave L Wave
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12. Body Waves
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P Wave
S Wave

13. Surface Waves
 Rayleigh Waves and Love Waves
 Travel just below or along the ground’s surface
 Slower than body waves; rolling and side-to-side
movement
 Especially damaging to buildings
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15. Faults
 A fault is a fracture in the Earth's crust
 3 main fault groups
 Faults are classified depending on how they move.
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16. The Normal Fault
Types of Fault
Strike-Slip Fault
Thrust Fault
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17. Normal Fault
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18. Thrust Fault
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19. Strike Slip Fault
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20. How does earthquake occurs?
 Most earthquakes happen along the edge of the oceanic and
continental plates. [Oceanic plates are under water,
continental plates are above.] The earth's crust (the outer
layer of the planet) is made up of a bunch of pieces, called
plates. The plates get moved around by the liquid layers of
magma underneath the Earth's crust. The plates are always
bumping into each other, and pulling away from each other
or past each other. Earthquakes usually happen when two
plates are running into each other or sliding past each other.
They can also happen along faults, too though.
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21. The Seismogram
 The device which records
Earth tremors
 A pendulum swings when
the earth moves
 The pen attached to the
pendulum records the
movement
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22. The Richter Scale
 Measures earthquake magnitude.
 Based on the amplitude of the wave produced on the
Seismograph.
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23. How are Earthquakes Measured? Richter
Scale
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24. Major Earthquakes Zone in the World
• Red dots are
shallow
• Green are
intermediate
depth
• Blue and purple
are deep
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25. The 10 Most Powerful Recorded
Earthquakes
Location Date Magnitude
1. Chile 22 May 1960 9.5
2. Prince William Sound, Alaska 28 March 1964 9.2
3. Off the west coast of northern
Sumatra
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26 December 2004 9.1
4. Kamchatka 4 November 1952 9
5. Arica, Peru (now part of Chile) 13 August 1868 9
6. North Pacific coast of America 26 January 1700 9 (estimated)
7. Off Bio-Bio, Chile 27 February 2010 8.8
8. Coast of Ecuador 13 January 1906 8.8
9. Lisbon 1 November 1755 8.7
10. Assam-Tibet 15 August 1950 8.6

26. Tsunami
 A tsunami is a giant wave
(or series of waves) created
by an undersea earthquake,
volcanic eruption.
 Period 10 - 60 min,
Wavelength 100 - 800 km,
velocity 230 m/sec (500
mph)
 At coast waves slow down
and pile up and come on
shore like a very rapidly
rising tide
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27. Earthquakes in Bangladesh
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28. Earthquakes Zone in Bangladesh
 In the north and northeast of Bangladesh, there are
areas of high seismic activity and some of the major
earthquakes originating in these areas. The whole of
Bangladesh is divided into three seismic zones. The
northern part of the country that includes the greater
districts of Rangpur, Mymensingh, and Sylhet are in
the Zone-I where earthquake shock of maximum
intensity.
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29.  The Zone-II includes the
greater districts of
Dinajpur, Bogra, Dhaka
and Chittagong and the
shocks of intensity of VIII
are possible. The southern
part of the country, the
least active region, where
the maximum intensity is
not likely to exceed VII, is
in the Zone-III. The experts
suggest not to construct
normal buildings with
more than 60m height.
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Earthquakes Zone in
Bangladesh cont.

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31. Last 2 Years Earthquake Statistic in
Bangladesh & Places Near Bangladesh
1. 1 years ago, Sylhet,
Bangladesh, 60 km depth.
2. 1 years ago, Dhaka,
Bangladesh 45 km depth
3. 1 years ago, Sikkim, India,
57 km depth
4. 2 years ago, Assam, India
53 km depth.
5. 2 years ago,
Rangamati,Bangladesh,
48 km depth
6. 2 years ago, Manipur,
India, 69 km depth.
7. 2 years ago, Maulvi Bazar,
Sylhet, Bangladesh, 73 km
depth
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33. Earthquake and Dhaka City
 Geologically active faults within 50
to 500 km distance from Dhaka.
 Dhaka is among the 20 major
world cities that are at the greatest
risk from earthquakes.
 Some of these earthquakes
especially the 1762, 1812,
1865,1885 and 1897 happened in
Dhaka.
 If 7-8 grade in Richter Scale
earthquake happen in Dhaka 70-
80 percent of the concrete
structures in the city would just
collapse & 30,00,000 peoples will
die.
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34. Effect of Earthquake
 Ground shaking: Shaking of the ground caused by the
passage of seismic waves, especially surface waves near the
epicenter of the earthquake are responsible for the most
damage during an earthquake.
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35. Effect of Earthquake Cont.
 Damage to man-made structures: Damage to man-made
structures, such as roads, bridges, dams and buildings from
ground motion.
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36. Effect of Earthquake Cont.
 Fires: Fires, often associated with broken electrical
and gas lines, is one of the common side effects of
earthquakes. Gas is set free as gas lines are broken
and a spark will start bringing "inferno". To complicate
things water lines are broken and so there is no water
to extinguish the fire.
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37. Effect of Earthquake Cont.
 Flooding: Flooding can come from many sources such as
broken water main pipes, dams that fail due to the
earthquake and earthquake-generated tsunamis.
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38. Effect of Earthquake Cont.
 Tsunami:
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39. Positive Effects of Earthquake
 Give knowledge insight in Geology
 Push Minerals and Metals to the Surface
 Make Fossil Fuels Easier to Access
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40. Earthquake Preventive Design
 All structure should be designed according to BNBC – 2006
code
 33% extra reinforcement provision to reduce earthquake
effect
 Residential building (5/ 6 storied) may be constructed with
L-type corner column and 2/3 T-type inner column tied
with beam
 To make it tight 8”x 12” column section with 5” to 8” brick
wall thickness may be selected
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41. Earthquake Preventive Design Cont.
 Furthermore, the following general principles may be
followed:
 (a) Ht. of each floor should be 10’
 (b) Foundation must be laid on hard soil
 (c) Framed structure should be preferred rather than brick
structure
 (d) Where frame structure is not possible, brick wall should
be reinforced vertically & horizontally
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42. Basic Recommendations for Earthquake
Protection
 Have ready first-aid kit,
Before the Earthquake:
torches, battery-operated
radio, batteries etc and some
provisions in a place known to
everyone.
 Make an emergency action
plan and ensure that the
family gathers in a secure
place.
 Prepare a telephone list so
that, if necessary, you can call
the civil protection, fire,
medical emergency or police
services.
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43. Basic Recommendations for Earthquake
Protection
During the earthquake:
 If you are inside a building,
stay inside; if you're outside,
remain outside.
 Inside a building, look for
strong structures,
underneath a table or bed,
underneath a door lintel,
next to a pillar, supporting
wall or in a corner and
protect your head.
 Do not use the lift and never
run headlong towards the
exit.
 Extinguish all fires. Do not
use any type of flame
(match, lighter, candle, etc.)
during or immediately after
the tremor
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44. Basic Recommendations for Earthquake
Protection
After the Earthquake:
 keep calm and ensure that others do the same. Prevent any
panic situations.
 Check whether anyone is hurt; give them any necessary first
aid.
 Do not repair damage immediately, except if there is broken
glass or bottles containing toxic or inflammable substances.
 Keep away from damaged buildings. Move to open areas.
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