Earthquake

Presentation

Engineering Geology & GeomorphologyCEN-223

Instructor

Anisuzzaman Khan

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Group Name

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Topic

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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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Contents

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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

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

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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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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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:

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Types Depth of focus (km)

Shallow Earthquake 60

Intermediate Earthquake 60-300

Deep Earthquake > 300

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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Seismic Waves

Two types:

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Body waves Surface waves

P Wave S Wave R Wave L Wave

Body Waves

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P Wave

S Wave

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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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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The Normal Fault Strike-Slip Fault

Thrust Fault

Types of Fault

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Normal Fault

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Thrust Fault

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Strike Slip Fault

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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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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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The Richter Scale

Measures earthquake magnitude.

Based on the amplitude of the wave produced on the

Seismograph.

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How are Earthquakes Measured? Richter

Scale

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Major Earthquakes Zone in the World

• Red dots are

shallow

• Green are

intermediate

depth

• Blue and purple

are deep

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The 10 Most Powerful Recorded

Earthquakes

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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

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

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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Earthquakes in Bangladesh

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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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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.29

Earthquakes Zone in

Bangladesh cont.

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

depth31

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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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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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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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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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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Tsunami:

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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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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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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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Basic Recommendations for Earthquake

Protection

Have ready first-aid kit, 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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Before the Earthquake:


Protection

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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During the earthquake:


Protection

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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After the Earthquake:

Earthquake

Environment

Transcript of Earthquake