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Causes of Earthquake and their Effects on Lives & Properties

Gp Capt Shafiullah, psc

Introduction

1. Earthquakes are natural phenomena that have to occur because

of internal geological requirements. They may occur all over the

world at any time of the day or without any warning. Normally,

earthquakes occur along the fault-lines but it was seen that

earthquakes occurred within the tectonic plates in areas which

were declared earthquake-free-zones. Japanese city of ‘Kobe’ is

an example. The city was considered quite safe and many

industries were developed there. A worst earthquake hit the city

on 19 Jan’95, causing losses of lives and properties of billions

of dollars within 20 to 30 seconds. Bangladesh is most likely to

be affected by any strong to major earthquake because of its

close proximity to the active seismic faults running along the

southeastern, eastern and northern periphery.

Expert geologists opine that if an earthquake of the Richter

scale of six or above occurs within the country or around the

close proximity of the Himalaya and lingers for 20 to 30 seconds

or more, then a widespread destruction of lives and properties

would take place on the major cities of Bangladesh. If

accompanied with aftershocks, like the ones happened during

recent earthquakes in Gujarat, northern Turkey and Algeria,

Pakistan etc, catastrophic devastation would occur particularly

over the mega-city of Dhaka. It would be very difficult for the1

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RESTRICTEDsurvivors to handle the situation during post disaster

management. Old buildings and structures would be the worst

affected. Multi-storied and non-engineered buildings, slumps,

roads, bridges, over bridges etc would be in ruins. Gas and

electric lines, sewerage lines, water lines etc established

haphazardly would be affected heavily. In this article, an

attempt is made to briefly describe the causes and effects of

earthquakes on lives and properties. Damage photographs of other

earthquake-hit countries were used to give a feeling of what

types of damages could occur in major cities of Bangladesh. If

viewed carefully, readers may develop a bitter taste of what a

strong to major earthquake can do if happens within or around our

country.

Aim

2. The aim of this article is to discuss the causes and effects

of strong to major earthquakes on lives and properties including

utility services and suggest some mitigatory measures for the

main city dwellers.

Sequence of Discussion

3. The sequence of discussion is as follows:

a. Occurrence and Background of earthquakes.

b. What is seismology?

c. Seismic waves & their characteristics.

d. What is Earthquake?2

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f. Effects on Lives and Properties.

g. Effects on Lifelines or Utility services.

h. Preparatory and Mitigatory Measures.

j. ‘Do’s and Don’ts’ before, during and after the earthquakes.

k. Recommendations.

l. Conclusions.

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RESTRICTEDOccurrence and background of earthquakes

4. When Earthquakes Started Occurring: Geologists believe that

Earthquakes had been occurring ever since the creation of the

earth. The earth is comprised of a dozen of ‘Tectonic plates’

known as ‘continental’ and ‘sea’ plates. At the beginning, all

the plates were clustered together to be known as ‘Super

continent Pangea’. The plates are of various thickness. For

example, the sea plates are about 8 to 10 km thick and made up of

heavy & denser basaltic rocks compared to the continental plates

which are about 65 to 70 km thick and made up of lighter granite

particles. As a result, the sea plates are comparatively heavier

than continental plates. While moving, they collide themselves

and produce quakes at the colliding boundaries. On a yearly

average, one to two great (M>8), 15 to 18 major (7<=M<7.9), 100

strong (6<=M<6.9), 800 moderate (5<=M<5.9), 6000 light

(4<=M<4.9), 50,000 minor (3<=M<3.9) and innumerable micro (M<3.0)

earth quakes occur throughout the globe.

What makes the Plates move?

5. Heat inside the earth is the driving force behind the movement

of tectonic plates. Immense internal heat was built-up at the

centre during the early days of tectonic plate formation. Heat is

also produced during breakdown of the radioactive materials like

uranium, thorium, Potassium etc in the outer and inner cores.

Different ‘Plate movement’ including Indian plate and Convective

heat cells form inside the earth which make the plates move

slowly @ of 2 cm per year.

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RESTRICTEDWhat is inside the Earth?

6. The structure of the earth resembles that of an Apple. The

core looks like the seed, the mantle looks like the white pulp

and the crust looks like the outer skin of an apple as shown in

Fig-6 and Fig-7. Below the earth’s crust is the mantle that

extends to a depth of about 2900 km. The mantle is divided into

two layers such as outer semi-liquid -layer and inner semi-solid

layer. Rock in the upper mantle is very hot and viscous in

nature, somewhat like the softened hot tar on summer street. Rock

in the lower mantle is more rigid and dense because of greater

pressure exerted by the earth crust. The core consists of nickel

& iron material. It has two parts: Inner & outer parts. The

inner core is solid due to intense pressure from the top layers,

which is about two million times more than earth’s surface. The

core produces earth’s magnetic field and may reach to a

temperature of about 73000 C. The density effects are more than

temperature effect and hence inner core is solid in nature.

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Internet

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Fig-1: Shows the apple like structure of the Interior of the

earth. The solid core in earth’s center looks like solid seeds in

apple’s center.

6RESTRICTED

RESTRICTEDPlate Motion and effects of Collision.

7. The Earth and its inner contents are in constant motion. The

surface is fractured into a dozen of rigid plates. The plates

float on the slowly-moving molten mantle causing the plates move

slowly. During movement, the plates either collide head-on, or

split apart, or simply grind their edges together, giving rise to

different major faults. During head-on collision in the ocean

areas, the edge of the heavier plate plunges into hot mantle

below the lighter plates and deep ocean trenches or mountain

ridges are created along the line of collision. If the head-on

collision takes between two continental plates, high mountains

are created. When the plates pull away from each other, hot

‘Magma’ comes out from below, creating features like mid-oceanic

ridges and rift valleys. When the plates push past one another,

large faults develop and Earthquakes occur. Such theories of

occurrence of earthquakes were unanimously accepted by the

geologists and it is known as ’Tectonic plate theory’. Thus, when

plates collide, earthquakes occur at the collision boundaries.

What is Seismology?

8. Seismology is the study of Seismic waves generated byearthquakes:

a. A seismologist is a scientist who studies earthquakesand seismic waves.

b. A Seismograph is the instrument that measures theearthquake.

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RESTRICTEDc. A Seismogram is the recording itself. The wiggles on a

seismogram are caused by seismic waves generated by the

movement of soils along a fault line.

Seismic Waves & their Characteristics

9. What are seismic waves? Seismic waves are natural

mechanical waves caused by earthquakes. Their names came from the

Greek word ‘Seismos’, meaning ’Shaking’. Seismic waves are the

waves of energy released by the sudden breakage of rocks within

the tectonic plates or along the boundary lines of plates or

within the plates inside the earth or due to a human made nuclear

explosion. The waves emanate from the source where the quake is

generated.

Types of Seismic waves

10. Mainly, seismic waves are labeled into two groups:

a. Surface waves. They move over the earth surface and

characterized by: Large amplitude, long wave length, wide

range of band frequency or large bandwidth, slow movement

and generally are produced by shallow focus earthquakes.

They are also known as ‘Long waves’, and are most

destructive for infrastructure. They are of two types:

(1) Shear surface waves, also known as ‘Love waves’.

They move at a speed of 3 to 6 km/sec & vibrate the

ground from side to side.

8RESTRICTED

RESTRICTED(2) Compressional surface waves or Raleigh waves.They are comparatively slower and move at a speed of 2

to 5 km/sec and vibrate the ground in an elliptical

pattern..

b. Body waves. They move through the inner body of

the earth from the focus of earthquake. They are of two

types:

(1) Primary or ‘P’ waves or Compressional body waves.

They are called primary waves, because they travel at a

faster speed, 10 to 15 km/sec, to reach the seismograph

before other waves. They travel through all types of

materials including solids, liquids or gases. The

motion produced by the ‘P’-waves is an alternating

compression and expansion.

(2) Secondary or ‘S’ waves or Shear body waves.

They are called secondary waves because they are second

fastest to reach the seismograph at speed 6 to 8

km/sec. They vibrate the ground in a shearing motion,

movement being perpendicular to the direction of wave.

They are often the largest waves capable doing most of

the damage.

What is Earthquake?

11. An EQ is a sudden and rapid shaking of the earth caused

by the breaking and shifting of rock beneath the Earth's surface.

9RESTRICTED

RESTRICTEDThis shaking can cause buildings and bridges to collapse; disrupt

gas, electric, and phone services; and sometimes trigger

landslides, avalanches, flash floods, fires, and huge

destructive ocean waves (tsunamis). Buildings with foundations

resting on the un-consolidated soft landfills, old waterways, or

other unstable soil are at the risk of collapse. Earthquakes

caused by the release of elastic strain energy are called

tectonic earthquakes. The strength or size of an earthquake at

its center is determined by using Richter's scales (normally

based on instrumental recordings) while an Intensity scale is

used for describing the effects:

a. American Red Cross. ‘An earthquake is the way the Earth

relieves its stress by transferring it to the people who live

on it’. It is a sudden and rapid shaking of the earth caused

by the breaking and shifting of rocks beneath the earth

surface. Tectonic plates slowly move over, under, and past

each other. At times, the plates are locked together, unable

to release the accumulated energy. When the accumulated energy

grows strong enough, the plates break free to make earthquake

at the breaking point.’ Most of the earthquakes are

accompanied with aftershocks generated to readjust the new

position of the displaced rocks.

b. Britain Geological Society (BGS). An earthquake

is the sudden release of strained energy in the earth’s

crust resulting into shaking waves that radiate outward from

earthquake source. When the stresses in the crust exceed the

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weakness either in a pre-existing fault or newly developed

fault plane. The point where earthquake starts is termed as

‘Focus’ or ‘hypocenter’. The point at the surface directly

above the focus is called ‘Epicenter’. The yellow portion is

the rupture surface where earthquake originates.

Where do the Earthquakes Occur?

12. Places of Occurrence: Earthquakes can occur anywhere

throughout the world, but the vast majority of the quakes occur

along narrow belts, which range from a few kilometers to hundreds

of kilometers in length and width. These belts are the boundaries

between the tectonic plates and are geologically very active.

Causes of earthquakes remained a mystery until 1960s. During that

decade, seismologists plotted the epicenters of thousands of

quakes and found that the earthquakes occur along some well-

defined belts round the globe.

The plates are irregularly shaped and move relative to each other

over upper layer of the ‘Mantle’ called ‘Asthenosphere’. Most

earthquakes are related to Compressional or tensional stresses

built up at the margins of moving plates. The mantle is hot

enough to move upward through the gaps between the plates causing

quakes to occur in the sea belt and over the fault-gap-containing

land areas over the lands. However, earthquakes can also occur

around the sub-faults within the tectonic plates as happened in

case Gujarat (26 Jan’01) and Kobe earthquakes (19 Jan’95).

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RESTRICTEDHow deep the Quakes originate?

13. Depth of the quakes depends on the depth of the faults

where the rupture takes place and it can be anywhere inside the

earth. Deep inside the earth, rocks are constantly being

pressurized to move due to tectonic plate movement. The pressure

keeps on developing and developing until the stress is so great

that the rocks can no longer bear the tension. Tensional pressure

is released at the point of rupture. Earthquakes with focal

depths (distance from epicenter to Focus) of about 70 km are

classified as shallow Quakes. Earthquakes with focal depths from

70 to 300 km are classified as intermediate and those with depth

more than 300 km are called deep earthquakes. The focuses of most

earthquakes are concentrated in the crust and upper mantle.

Why Indian Plate Boundary is so active?

14. World’s most destructive earthquakes occur along subduction

zones. Indian plate is a subducted plate. That is the reason why

the Indian plate boundary is so active. When a large continental

boundary breaks into smaller pieces under tensional stresses, a

series of cracks are created, which may develop into a major

system of faults. When two plates slide past one another in a

grinding or shearing manner, large faults or fractures develop

where severe quakes occur. Indian plate started its journey from

south and subducted steeply below the Eurasian plate to form

Himalayan mountain ranges, Like Himalayas and Tibetan plateau.

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L ikely Effects on Lives and Properties

15. The effects of earthquakes on lives and properties will

depend on a number of widely varying factors. These factors are:

a. Intrinsic to the earthquake . It depends on its magnitude,

type (moderate or severe), location (within the country or

outside), or depth of focus (shallow or deep).

b. Geologic conditions where effects are felt . It depends

on the distance from the epicenter, path of the seismic waves,

types of soil, and Liquefaction.

c. Societal/structural conditions reacting to the earthquake.

It depends on the quality of construction, preparedness of

populace, or time of day, season of the year etc. Damage

would be less if construction standards are relatively high,

and the populace relatively prepared. However, soft, highly

saturated soils near waterbeds or around the periphery loose

soils or deep ditches near the rivers or large reservoirs

would cause failures of large highway structures even if far

away from the epicenter.

d. A ftershocks. After shocks are associated with many

earthquakes. Such shocks cause further damages to the already

shaken structures. The damage of Gujarat city is an an example

what an moderate to severe earthquake could to the properties.

The damage list of Gujarat quake, shown in Table-1, gives an

idea how much damage Dhaka city might have in future quakes:

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Loss of lives 21000 persons.Population affected 15.9 million.

Cattle Death 20717 numbers.

Houses Destroyed 175000 Pucca, 167000 Kachcha &

16000 huts.Houses Damaged 490000 Pucca, 349000 Kachcha

& 34000 huts. 

Industrial establishments Rs. 50, 000 million.

Commercial establishments Rs. 30, 000 million.

Personal Properties Rs. 3, 870 million.

Household Properties Rs. 111, 950 million.

Public Utilities Rs. 6, 000 million.

Public Infrastructure &

Amenities

Rs. 10, 800 million.

Damage to Public Utilities Rs. 6, 000 million.

Total estimated loss Rs. 21, 2620 million.

16. All seismic waves such as ‘P’ and ‘S’ waves are likely to

shake the area wherever they penetrate from the hypocenter. They

affect severely in the areas close to epicenter. ‘Surface waves’

would also add to ground shaking to cause heavy structural

damage. Body and surface waves cause the ground, and consequently

a building, to vibrate in a complex manner. The catastrophic

damages to lives and properties that occurred in Gujarat, Kobe14

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Table-1: Loss of Lives and Properties (Approx) In Gujarat Quake (Source: Bhuj damage).

RESTRICTEDcity, Turkey, and Iran and very recently in northern Algeria

(May2003) bear the testimony of such seismic effects. A few

damage is shown below:

Effects on Lifelines / Utility Services

17. Lifelines or utility services are the linear systems

necessary to sustain human life and urban functions. These

systems include highways and bridges; power lines; gas lines;

hospitals; fire services; telecomm; water supply and sewerage

systems; railroads, river ports, airports etc. Dhaka city is well

clustered with the lifeline systems. Any earthquake of moderate

to severe magnitude for 20 to 30 seconds would certainly disrupt

the systems. If the Epicenters were originated within Bangladesh,

damage would certainly be more than those quakes originated

outside. Moreover, utility lines are not well structured in Dhaka

city. Lines may burst during intense body and surface seismic

wave shaking and cause massacre by igniting gas or electric fire.

Water and sewerage lines may burst or be blocked by ground

shaking or liquefaction, which practically happened in 1995 Kobe

earthquake, 2001 Gujarat quake and 2003 Algerian quakes.

Damages that are expected to occur on Dhaka city lifelines are

discussed below:

a. W ater. Moderate severe earthquake would disrupt the

lines as happened in Kobe city and Gujarat.

b. Wastewater and Sewerage lines. These lines are already in

shambles. Most of the drainages are blocked due accumulated waste15

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RESTRICTEDmaterials as can be understood from the inundation of roads due

to standing water during monsoon rains. If earthquakes occur,

these lines would be subject to further deterioration as happened

in recent Algerian quake.

c. Electrical Power Stations. When the present lines cannot

tolerate a moderate Tornado, how the old lines, both overhead &

underground, would sustain earthquake? Once damaged, it would

take long time to restore the systems. Moreover, damage of power

stations may lead to fire as practically in Kobe earthquake.

d. Natural Gas. Titas gas lines of different diameters inDhaka are pretty old. Any earthquake may disrupt the lines and

lead to leakage and devastating fires. Recently, a number of gas

stations have been established in Dhaka city, which are likely to

be affected leading to fire as happened in Kobe city shown below:

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RESTRICTEDe. Liquid Fuel. Dhaka city has a number of petrol pumps

scattered throughout the city. Earthquake shaking may lead to

leakage of petrol pumps leading to fire.

f. Roads and Highways. Dhaka city highways and narrow roads in

and around the dwelling houses would give up to the seismic wave

shaking. Some photos of damage highways in Kobe and Gujarat.

g. Railroads. Kamalapur railway complex and rail lines would

be subject to disruption as happened in Los Angeles and Gujarat

h. A irports . Zia Intl and Tejgaon airports would likely to be

affected as happened in other quake hit countries.

j. River ports and River bridges. Dhaka Sadar and

Pagla ghats are the river ports likely to be affected due to

liquefaction as happened in different river ports of California

and Japan quakes.

k. Educational Institutions, Hospitals & Medi-Care centre.

Most of educational institutions in Dhaka city are old and

fragile to tolerate earthquakes. All the hospitals in Dhaka city

are pretty old. As a result, educational institutes and medi-care

services would suffer heavily due seismic wave shaking. In

Gujarat and Algerian Quakes, most of the old hospitals and school

buildings suffered severe damages having the patients and

students killed due to falling debris. As per CNN correspondent

reports, during the recent earthquake that occurred on 8th

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RESTRICTEDOctober,2005 in Pakistan, it was seen that the hospitals and

medical centers made by the Govt employed contractors were

seriously damaged compared to privately owned ones.

18. Economic loss. The economy of the country would suffer

because of damage of business structures as well as lifelines.

Since authority is not well prepared, it would take months

together to start business activities afresh. The business and

dwelling apartments were heavily damaged in Gujarat and Kobe

cities causing losses worth of billion dollars. Economic and

lifeline losses in Gujarat alone are shown Table-2:

Railways Heavy damage to various station buildings, station

cabins, bridges, residential quarters and signaling

systems. Roads 650 km of national highways damaged, 100 km

severely.Bridges Most main road bridges were damaged. Ports Berths 1-5 at Kandla Port suffered major structural

damage.Telecomm 147 exchanges, 82,000 lines and optical fibre

systems damaged.Power 45 sub-stations, power supply to 50% of feeders and

nine towns were affected. Water Water supply to 18 towns and 1340 villages damaged

or destroyed. Fuel Jamnager refinery shutdown 26 January by power

failure. Crude oil and product pipelines were shut

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Schools Out of 1359 primary schools, 992 were destroyed.

Out of 38 secondary schools, 6 were destroyed, 14

suffered heavy damage and 12 were partially

damaged. Out of 128 non-government schools, 9 were

destroyed, 11 suffered heavy damage. Most of the

Govt owned schools and institutions were damaged

heavily.Environmenta

l

A huge loss in the gardens around the main city

centre.

Preparatory and Mitigatory Measures

19. Why to prepare for earthquake? Dhaka city has changed

significantly in last few decades. Population has increased

manifold. A large amount of infrastructures have come up which

might not have been designed to withstand intense seismic

shaking. Some older buildings particularly in old Dhaka would

hardly tolerate even moderate quakes. Any future earthquakes

would cause damage to buildings, displace items within buildings,

and disrupt basic utility services in the Dhaka city. No body can

stop the occurrence of earthquake but mitigatory steps could

reduce damages. By becoming aware of the hazards posed by

earthquakes and by taking precautions, we can drastically reduce

the loss of lives and properties, and make Dhaka city a safer

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RESTRICTEDplace to live. The choice is ours. A prepared person is never

caught in surprise.

What Mitigatory Measure?

24. Major causes of human deaths and injuries are due to the

collapse of structures people live in. Therefore, the mitigatory

measure should be making the dwelling structures strong enough to

withstand the earthquake seismic forces. This can be achieved by

developing a comprehensive building code with adequate provisions

for seismic design. The recently prepared Bangladesh National

Building Code has the provisions for earthquake resistant design

of buildings. In addition there are guidelines for non-engineered

construction of non-reinforced brick masonry, which are likely to

be damaged even with moderate seismic shaking.

However, the enforcement of the provisions of the code would

require intensive efforts from the appropriate authority. People

generally do not want to follow the building codes due to high

cost. The people require to be briefed that investment in pre-

earthquake planning and preparedness would yield much higher

returns than post-disaster measures in the form of relief and

rehabilitation. Keeping this in view, an integrated earthquake

management plans needs to be developed, particularly for large

urban areas, more so for Dhaka city. This would require a

comprehensive joint effort of various professionals including

engineers, fire fighters and civil defence personnel, geologists

and health care personnel. Special ‘Implementation cell’ and

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RESTRICTED‘Search and Rescue units with air elements’ have to be formed to

handle earthquake hazards. It will require specially trained

personnel, equipments, and sniper dogs to detect people buried

under debris of collapsed structures. Efforts are to be made to

study the strength of existing buildings of Dhaka city. If

possible, retrofitting of existing structures is to be undertaken

if found that the structures do not possess adequate strength.

This includes strengthening of existing structural components by

addition of reinforcing steel and concrete to existing beams,

columns, walls etc or by adding new structural elements. Urban

people would require to be awaked on the ‘Dos’ and ‘Don’ts’ of

the earthquake hazards.

Do’s and Don’ts to Reduce Earthquake Effects

25. What to Do Before an Earthquake. Following pointsare suggested:

a. Learn about the earthquakes and their impacts on lives

and properties. Learn how vulnerable your area or your

houses are to the earthquakes! Make sure that you have a

fire extinguisher, a battery-powered radio, a flashlight,

and extra batteries always available at home for emergency

uses.

b. Learn first aid and have a first aid kit box at home and

working place.

c. Learn how to turn off the gas, water, and electricity in

case of emergency.

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RESTRICTEDd. Make up a plan to educate and rehearse the family

members from time to time.

e. Don't leave heavy objects on shelves; they'll fall

during a quake.

f. Anchor or tie-up heavy furniture, cupboards, and

appliances to the walls or floor so that they do not fall

off during seismic shaking.

g. Check your house and other belongings from time to time

to see whether they are quake resistant. If not, take

precautionary measures as per the advice of the experts.

26. What to Do During an Earthquake. Here are some suggestions:

a. Stay calm! If you're indoors, stay inside. If you'reoutside, stay outside. Do not run abruptly because falling

objects might hit you.

b. If you're indoors, stand against a wall near the center

of the building; stand in a doorway, or crawl under heavy

furniture like a heavy desk or table and keep your head

covered up as shown in Fig-53. Stay away from windows and

outside doors.

c. If you're outdoors, stay in the open area away from

power lines or anything that might fall. Stay away from

buildings; loose stuff might fall off the building or the

building could fall on you. 22

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RESTRICTEDd. Don't use matches, candles, or any flame; broken gas

lines may leak and catch fire.

e. If you're in a car, stop the car and stay inside the car

until the earthquake stops.

f. Don't use elevators; they'll probably get stuck anyway.

27. What to Do After an Earthquake:

a. Check yourself and others for injuries; provide first

aid for anyone who needs it.

b. Check water, gas, and electric lines for damage. If

found damaged, shut-off the valves. Check for the smell of

gas. If you smell it, open all the windows and doors, leave

immediately, and report it to the authorities.

c. Turn on the radio to listen for any instruction.

d. Stay out of damaged buildings; debris may fall on you

due to aftershocks.

e. Be careful while walking around broken glass and debris.

Wear boots or sturdy shoes to save from cutting your feet.

Never walk on bare foot. If possible, wear helmet while

entering a damaged building.

f. Be careful of fallouts from the cracked roofs; they may

fall on you.

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RESTRICTEDg. Be careful of flushing the toilets before the sewerage

lines are checked. Be careful of children running here &

there to save them from aftershocks.

h. Stay away from damaged wall; they may fall on you during

aftershocks.

R ecommendations

28. Following recommendations are given:

a. Bangladesh National Building Code Provisions should be

strictly followed for design and construction of all

buildings and building services. Competent professionals

should evaluate the strength of existing structures to

withstand seismic shaking and retrofitting be done if

required.

b. A thorough and refined assessment of the seismic risk in

various parts of Dhaka city be done and the dwellers be

informed to take appropriate measures.

c. Study of liquefaction potentials in different parts of

Dhaka city close to river belts and arrange computerized

micro-seismic monitoring system, shown in Fig-54, for Dhaka

City.

d. Review and updating the building code at regular

intervals of 5 to 7 years to incorporate the findings of any

refined studies.

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RESTRICTEDe. Developing adequate facilities for education, training

and research. This should include:

(1) Training of teachers, students, dwellers etc.

(2) Organization of training programs for different

categories of engineers and technicians involved in

planning, design, construction and maintenance of Govt

and non-Govt installations.

f. Programmes for educating engineers specialized in

earthquakes, seismologists and geophysicists through

seminars or workshops.

g. Development of laboratory facilities for testing of

structures subjected to earthquakes.

h. Development of seismic observations, at least three, and

micro seismic instrumentation of selected new structures.

k. Development of Emergency Manual detailing the actions to

be taken before, during and after the earthquakes. This may

be made a part of the overall Disaster Preparedness Plan

under the Disaster Management Bureau.

l. Development of Public Awareness Programme including

simple instructions on do’s and don’ts through media like

radio, television, newspapers and periodicals. These may be

included in the school curriculum in high-risk areas.

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RESTRICTEDm. Organizing regular Earthquake drills in high-risk areas.

n. Development of simple guidelines for non-engineered

constructions, in Bangla, and disseminating them to people

living in the slumps through ward commissioners.

p. Establishment of at least three seismic centers at

Rangpur, Dhaka and Chittagong respectively for measuring the

location of epicenters and focus of the quakes generated

within or outside the country.

Conclusions

29. Most of the cities of the world including Dhaka city are

vulnerable to various types of natural disasters. Weak to

moderate earthquakes are occurring daily over the globe signaling

their presence and warning the people to be careful. Effects on

lives and properties any where would depend on the location of

epicenter and structural design of the affected area. The Gujarat

and Kobe Earthquakes are the striking examples of what

earthquakes can do to a modern industrialized society. Most of

what happened in quake-hit countries could have been reduced if

people were aware of what mitigatory measures could have been

adopted for quake prone areas. The loss of thousands of lives and

the hardships of hundreds of thousands of affected residents are

terribly awful. Similar situation is likely to occur in Dhaka

city at any time as warned by American Geologists and old seismic

records from UK and Indian Geological Archives say that Dhaka

city was affected in the past. People in Dhaka city are quite

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RESTRICTEDlucky in the sense that strong quakes have not occurred in or

outside the country close to Shillong massif or along Myanmar-

Bangladesh border in last fifty years. Mir Fazlul Karim,

Director, Geological Service of Bangladesh, opine that

northeastern parts of Indian plates are long due for a severe

quake. If so, Dhaka city with its massive infrastructures and

thickly concentrated population is going to be affected. Recent

quakes in northern parts of Afghanistan, Iran, Turkey and Algeria

remind us what would happen to our capital city. We have lots of

lessons to learn from those effects and the real lesson is that

we must motivate our people to rectify, replace or strengthen

deficient and faulty structures along with utility systems.

37. Vulnerable cities are fast growing in terms of

infrastructures and inhabitants. Although, Dhaka city is not

sitting on the faults, yet it is not too far away from active

faults created around Himalayas and Tibetan plateau. A good

number of faults and sub-faults were produced due to the tectonic

subduction and deformation due to Indian plate’s head-on

collision with Eurasian plates and quakes of various magnitudes

originated around the Himalayan regions.

30. The history of major earthquakes in Bangladesh and

surrounding areas indicates that the city experienced moderate

jolts during the earthquakes of 1897, 1918, 1934 and 1950. Those

earthquakes caused significant destruction in the then thinly

populated Dhaka city. Similar magnitude earthquakes will cause

unprecedented hazards in the present day mega-city of Dhaka

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RESTRICTEDhaving huge infrastructure and industrial set up. On 19 Dec’01,

an earthquake of magnitude 4.2 has severely jolted Dhaka city and

damaged Dhaka central jail. The damages caused by the quake are

insignificant but it created a very high sense of fear among

million of city dwellers. The Earthquake triggered the thinking

tanks of the city to rethink about urban structural design. It is

not known what will happen if there occurs an earthquake of

Magnitude more than Six. Study done by BUET students found that

almost all the structures in old Dhaka city would be smashed to

surface even with moderate quakes as happened to similar

structures in Gujarat and Iran.

31. For the safety of millions people and development of

earthquake hazard awareness, it is necessary for development of

micro-seismic monitoring system for Dhaka City and surrounding

regions for measurement of soil movement due to possible seismic

activity. At least three seismic centers are required to

accurately locate quake center.

32. Earthquakes cannot be predicted but damages caused by

their abrupt occurrence could be reduced if vulnerable

people are educated to make structural designs suiting to

tolerate the seismic wave shaking. Earthquakes have to occur

to meet the geological requirement inside the earth. On a

yearly average, one to two great (M>8), 15 to 18 major

(7<=M<7.9), 100 strong (6<=M<6.9), 800 moderate (5<=M<5.9),

6000 light (4<=M<4.9), 50,000 minor (3<=M<3.9) and

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RESTRICTEDinnumerable micro (M<3.0) earth quakes occur throughout the

globe. Most of them occur inside oceans, which saves us

from catastrophic damage. It is possible that major

earthquakes could take place in the Himalayan region.

Therefore, it would be appropriate to make relevant

strategic plans for Dhaka city to face any probable seismic

activity due to earthquake originating inside or outside the

country.

33. The occurrence of earthquake is a global phenomenon.

Earthquakes occur along the fault lines that were created through

tectonic and geological processes. Recent earthquake over the

Hill Tracts areas imply that Fault lines along the eastern side

of Bangladesh are getting active. In last thirty months, about

97 small magnitudes earthquakes occurred in the southeastern

parts of Bangladesh and jolted the areas resulting cracks in the

buildings, roads and hills. These mild earthquakes are the wakeup

calls to prepare city dwellers for a great earthquake in the

coming days. Photographs of recent earthquake in ‘Barkol’ area.

Earthquakes are the most disastrous of all the natural

calamities as they affect large areas causing death, injuries and

destruction of physical resources on a massive scale within few

seconds. They occur without any pre-warning. The extent of

devastation on any place depends on earthquake’s magnitude,

location, time and season of the year. Quakes may not be avoided

but damage in Dhaka city could be reduced if the inhabitants are

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RESTRICTEDmade aware and kept prepared for any eventuality. Finally,

earthquake disaster mitigation plan is required to be made for

Dhaka city incorporating pre, during and post-earthquake

measures.

References

1. Karim M.F, State of Earthquake Research and Monitoring in

Bangladesh and State of Building structures in Dhaka city,

presented in the International Workshop on Seismic Analysis in

the South Asian region, Kathmandu, Nepal, 10 to 14 Sep’01.

2. Ali, M.H. (1997). “Seismic Risk and Building Resistance inDhaka City”, Report submitted to United Nations Center for

Regional Development, Nagoya, Japan.

3. Upal Chandra, "Earthquakes of Peninsular India--A

seismotectonic study", Bulletin of the Seismological Society of

America, 1977, Vol. 67, No. 5, pp. 1387 to 1413.

4. US National Earthquake Information Centre http:// earthquakes.usgs. gov/

5. Active Tectonics, Active Tectonics Web Server

http: //www. muohio. edu/ tectonics /activetectonics.html ,

6. Lecture Notes on ‘Active tectonics, neotectonics, and crustaldeformation’ http://www- geology.ucdavis.edu/~GEL214/GEL214-2.html

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RESTRICTED7. http:

//www.seismo.unr.edu/ftp/pub/louie/class/100/interior.html

8. http: //www.seismo.unr.edu/ftp/pub/louie/class/100/seismic

waves.html

9. http: //www.asc.india.org/menu/seismic.htm.

10. http: //www.ege.com/publiccation/kobe/building.htm

11. http: //pubs.usgs.gov/publications/text/understanding.htm

12. http: //pubs.usgs.gov/publications/text/unanswered. htm

Bio-data

Group Captain Mohammad Shafiullah, psc was born on 30 June 1952

in the district of Noakhali. After completing MSc in Applied

Chemistry from Dhaka University, he joined Bangladesh Air Force

and was commissioned in the Meteorological branch in the year

1976. He attended various professional courses at home and

abroad. He attended Advance Meteorology, Cyclone & other

Disasters management and Satellite Courses in the Indian Air

Force officers’ Training Institute, Coimbatore, and Taminadu. He

also did advance courses in Officers’ Training Academy in

Mississippi and Connecticut, USA. He also attended Arabic

Language course & Advance Computer Course in BAF. He gained MBA

(Finance) degree from IBA, Dhaka University in 1996. He is a

graduate from DSCSC, Mirpur. He has number of publications in the

Military journals/Magazines. He presented a number of Keynote

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RESTRICTEDpapers on Earthquake, Disaster Management etc in different

seminars/symposiums. He is married and has two daughters. He held

various Command and Staff appointments in Bangladesh Air Force.

He served Director, Met Directorate, Education Directorate, and

Officer Commanding of Air Head Quarter (Unit). He also was the

Instructor at BAF Academy. At present he is serving as an

Assistant Professor and MBA Program Coordinator, School of

Business studies in Southeast University, Banani, Dhaka and

teaching MBA courses.

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MBA program Coordinator, Facultyoff Business Administration,Eastern University, Dhanmandi,