Challenges, Strategies and Solutions of Disasters

8/10/2019 Challenges, Strategies and Solutions of Disasters

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i

hallenges Strategies

an~

Solutions of Disasters due to

Earthquakes Landslides

Floods and their Management

Mrinal K.Ghose

Ph.D, D.Sc.

Emeritus Professor :Department of Biotechnology, West

Bengal University of Technology Kolkata-700064

[email protected]

Abstract

India is among the world's most disaster prone

areas and a large part of the country is exposed to

the natural hazards like floods, cyclones, droughts

and earthquakes. They are causing significant

disruption of socio-economic life of communities

leading to loss of life am :property. This paper

examines the unique geo-climatic conditions, which

have exposed this country to natural catastrophes

traditionally and it focuses the background of the

United Nations' declaration of 1990-2000 as

International Decade for Natural Disaster

Reduction This paper discusses the physical form

of geosphere causing earthquake arise from plate

tectonic processes, surface earth movement causing

lands slide, stream and river phenomena causing

floods. Concerned UJoiththe impact of natural

disasters preparedness and prevention are integral

components of the development process; the

Governments qt the Central and State levels are

gradually evolving strategies, policies and

programmes for natural disaster mitigations,

preparedness and prevention. The importance of

forecasting, satellite and remote sensing,

computerized systems of vulnerability and risk

assessment and other technologies for warning and

monitoring has been described. Hazard

vulnerability in respect of earthquakes, wind and

cycles, floods has been discussed. Land-use zoning

and design guidelines for improving hazard

resistant construction of buildings and housing

have been highlighted in this paper. Recognizing

the usefulness of the Vulnerability Atlas for

formulating pro-active policies to face the threat of

natural hazards, is being brought to the notice of

the development planners, decision makers,

professionals and householders. Seismic occurrence

and cyclone hazard monitoring by Indian

Meteorological Department (IMD) and flood

monitoring by the Central Water Commission are

being done. The Bureau of Indian Standards

Committees on Earthquake Engineering and Wind

Engineering has a Seismic Zoning Map and the

Wind Velocity Map including cyclonic winds for the

country. The Central Water Commission has a Flood

Atlas of India. Strategies to be adopted and

proposed Action Plan for consideration of the

Government for evolving a National Policy keeping

in view of the Govt. of India's commitment to the

Yokohama Strategy for Natural Disaster Reduction

are discussed. Recommendations and proposed

Action Plan and the major issues are highlighted

The objectives of India's National Policy for natural

disaster reduction, goals, legislation needed,

stakeholders in the process of disaster mitigation,

pre-disaster pro-active approach in disaster

management are discussed

eywords Hazard, tectonic, forecasting,

prevention, vulnerability, awareness

1.0 Introduction

The natural hazards like floods, cyclones,

droughts and earthquakes are not rare or unusual

phenomenon and India is among the world's most

disaster prone areas A large part of the country is

exposed to such natural hazards, which often turn

into disasters causing significant disruption of

socio-economic life of communities leading to loss

of life and property. The unique geo-climatic

conditions, which have exposed this country to

natural catastrophes traditionally and it focuses the

background ofthe United Nations' resolution. UN

declaration of 1990-2000 as International Decade

for Natural Disaster Reduction brings into sharp

focus the miseries caused by natural disasters and

the need to take action in this regard. Concerned

with the impact of natural disasters preparedness

and prevention are integral components of the

development process; the Governments at the

Central and State levels are gradually evolving

strategies, policies and programmes for natuTal

disaster mitigations, preparedness and prevention.

Recognizing the usefulness of the Vulnerability

Atlas for formulating pro-active policies to face the

threat of natural hazards, is being brought to the

notice of the development planners, decision

makers, professionals and householders. Seismic

occurrence and cyclone hazard monitoring by

Indian Meteorological Department (IMD) and flood

monitoring by the Central Water Commission are

being done. In addition Geological Survey of India

and the Department of Earthquake Engineering,

University of Roorkee makes noteworthy

*Key note address presented in the National Seminar On Environmental Issues: Protection, Conservation

Management held at Visva Bharati, Shantiniketan on

22- 23

Nov'2013.

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Mrinal K hose

contributions in this regard. The Bureau of Indian

Standards Committees on Earthquake Engineering

and Wind Engineering has a Seismic Zoning Map

and the Wind Velocity Map including cyclonicwinds

for the country. The Central Water Commission has

a Flood Atlas of India. The importance of



assessment and other technologies for warning and

monitoring cannot be tgnored. The objective of this

paper is 1i) tnalyze hazard vulnerability in respect

of earthquakes, landslides and floods with specific

reference to India and to focus on land-use zoning

and design guidelines for improving hazard

resistant construction of buildings and housing.

2.0 Physical form of geosphere

The geosphere has a highly varied, constantly

changing ph~sical form. Most of earth s land mass

is contained in several massive continents

separated by vast massive oceans. Towering moun-

tains rangespread across the continents, and in

some places the ocean is at extreme depths. Earth-

quakes, which often cause great destruction and

loss of life, volcanic eruptions, which sometimes

throw enough material into the atmosphere to

cause temporary changes in climate, serve as

reminders that the earth is a dynamic, living body

that continues to cb-ange. There is convincing

evidence that the close fit between the western

coast of Africa and the eastern coast of South

America, that widely separated continents were

once joined a hd have moved relative to each other.

The ongoing phenomenon is known as continental

drift. It is now believed that 200 million years ago

much ofthe earths land mass was all part of a super

continent, now called Gowanda land. This continent

spilt apart to form to present-day continents of

Antarctica, Australia, Africa, and South America,

Madagascar, the Seychelles Islands, and India are

described by the theory of plate tectonics (Candie

1997).

This theory views earth s solid as consisting

of several rigid plates, that move relative to each

other. These plates drift at an average rate of

several centimeters per year atop a relatively weak,

partially molten layer that is a part of earths upper

mantle called the asthenosphere. The science of

plate tectonics explains the large-scale phenomenon

that effect the geosphere, including the creation of

and enlargement of oceans as oceans floors open

up and spread, the collision and breaking apart

continents, the formation of mountain chains,

volcanic activities, the creation of islands of volcanic

origin, and earthquakes. The boundaries where the

most geological activity such as earthquakes and

volcanic activity occur. These boundaries are of

three following types.

.

Divergent boundaries, where plates are

moving away from each other, occurring on

ocean floors. These are the regions in which

hot magma flows upward and cools to produce

new solid lithosphere. This new solid material

creates ocean ridges.

Convergent boundaries where plates move

toward each other. One plate may be pushed

beneath the other in a subduction zone in

which matter is buried in the asthenosphere

and eventually remolded to form new magma.

When this does not occur, the lithosphere is

pushed up to form mountain ranges a collision

boundary.

Transform fault boundaries in which two

plates slide past each other. These boundaries

create faults that result in earthquakes.

.

.

3.0 rthqu kes

. -

Earthquakes usually arise from plate tectonic

processes and originate along the plate boundaries

occurring as motion of ground resulting from the

release of energy that accompanies in abrupt

slippage of rock formations subjected to stress along

a fault. Basically, two huge masses trend to move

relative to each other, but are locked together along

a fault line. This causes deformation of rock

formations, which increases with increasing stress.

Eventually, the friction between the two moving

bodies is insufficient to keep them locked in place,

and movement occurs along an existing fault, or a

new fault is formed. Freed from constraints on their

movement, the rock undergoes elastic rebo~nd,

causing the earth to shake. In addition to shaking

of ground, which can be quite violent, earthquakes

can cause ground to rupture, subside or rise (Keller

1996). Liquefaction is an important phenomenon

that occurs during earthquakes with ground that

that is poorly consolidated and in which the water

table may be high. Liquefaction results from

separation of soil particles accompanied by water

infiltration, when this o,~curs; the ground behaves

like a fluid.

The location of the initial movement along a

fault that causes an earthquake to occur is called

the focus of the earthquake. The surface location

directly above the focus is the epicenter. Energy is

transmitted from the focus by seismic waves.

Seismic waves that travel through the interior of

the earth are called body waves and those that

traverse the surface are surface waves. Body waves

are further categorized as P-waves, compressional

vibrations that result from the alternate

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compression of and expansion of geographical

material, and S-waves, consisting of shear waves

manifested by sideways oscillation ofmaterial. The

motions of these waves are detected by a

seismograph, often at a great distances from the

epicenter. The two types of waves move at different

rates, with P-waves moving faster. From the arrival

times of the two kinds of waves at different

seismographic locations, it is possible to locate the

epicenter of the earthquake.

The loss of life and destruction of property by

earthquakes make them some of nature s more

natural phenomena. The destructive effects of an

earthquake are due to the release of energy.

Literally millions oflives have been lost in the past

earthquakes, and the damage from a developed

urban area can be millions of dollars. Earthquakes

may

cause catastrophic secondary effects, especially

large, destructive ocean waves are called tsunamis.

Adding the terror of earthquakes is their lack

of predictability. An earthquake can strike at any

time. Although: .the exact prediction of earthquakes

has so far eluded the investigators, locations where

the most earthquakes are most likely to occur are

much more well-known. These are located along the

in lines corresponding to boundaries along which

tectonic plates collide and move relative to each

other, building up stresses that are suddenly

released when earthq~akes occur. Such inter plate

boundaries are locations of preexisting faults and

breaks. Occasionally, however, an earthquake will

occur within a plate, made more massive and

destructive because for it to occur the thick litho-

sphere has to be ruptured.

The scale of earthquakes can be estimated by

the degree of motion that they cause and by their

destructiveness. The former is termed as the

magnitude of an earthquake and is commonly

expressed by the Richter scale. The Richter scale is

an open-ended, and each unit is in the scale reflects

a ten-fold increase in magnitude. Hundred thousand

earthquakes from three to three occur each year,

they are detected in seismographs, but are not felt

by humans. Minor earthquakes range from four to

five on Richter scale and earthquakes cause damage

at a magnitude greater than about five. Great

earthquakes, which occur about once or twice a year,

register over eight on the Richter scale.

The intensity of an earthquake is a subjective

estimate of its potential destructive effect. On

Mercaulli intensity scale, an intensity III earth-

quake feels like the passage of heavy vehicles; one

with an intensity of VII cause difficulty in standing

, damage to plaster, and dislodging of loose brick,

whereas a quake with an intensity of XII causes

virtually of total destruction, throws objects

Mrinal hose

upward, and shifts huge masses of earthen

material. Intensity does not correlate exactly with

magnitude.

Distance from the epicenter, the nature of

identifying strata, and the types of structures

affected may all result variations in intensity from

the same earthquake. In general, structures on

bedrock will survive with much less damage than

those constructed on poorly consolidated material.

Displacement of ground along a fault can be

substantial, for example, up to six meters along the

San Andreas fault during the 1906 San Francisco

earthquake Such shifts can break pipelines and

destroy roadways. Highly destructive surface waves

can shake vulnerable structures apart. The shaking

and movement of ground are the most obvious

means by which earthquakes cause damage. In

addition to shaking it, earthquakes can cause the

ground to rupture, subside, or rise. Liquefaction is

an important phenomenon that occurs during

earthquakes with ground that is poorly consoli-

dated and in which the water table may be high.

Liquefaction results from separation of soil particles

accompanied by water infiltration such that the

ground behaves like a fluid.

Another devastating phenomenon consists of

tsunamis, large ocean waves resulting from

earthquake-induced movement of ocean floor

(Dudley and Min 1998). Tsunamis sweeping

onshore at speeds up to 1000kmlhr have destroyed

many homes and taken lives, often large distances

from the epicenter ofthe earthquake, itselfCSatake

et.al 1995). The effect occurs when a tsunami

approaches land and forms huge breakers, some as

high as 10-15 meters, or even higher. On April 1,

1946, an earthquake off the coast of Alaska

generated a tsunami estimated to be 30 meters high

that killed 5 people on a nearby lighthouse. About

5 hours later a Tsunami generated by the same

earthquake reached Hilo, Hawaii, and killed 159

people with a wave exceeding 15 meters high. The

March 27, 1964, Alaska earthquake generated a

tsunami over 10 meters high that hit a freighter

docked at Valdez, tossing it around like matchwood.

Miraculously, nobody on the freighter was killed,

but 28 people on the dock died.

Literally millions oflives have been lost in the

past earthquakes, and damage from the earthquake

in developed urban area can easily run into billions

of dollars. As examples, a massive earthquake in

Egypt and Syria in 121 AD took over 1million lives,

one in Tangshan, China in 1976 killed about 650,000

and in 1989 Loma Prieta earthquake in California

cost about 7 billion dollars.

Significant progress has been made in

designing structures that are earthquake resistant.

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Mrinal K hose

An evidence of that, during 1964 earthquake in

Niigata, Japan, some buildings tipped-over on their

sides due to liquefaction of the underlying soil, but

remained structurally intact Other areas of

endeavor that can lessen the impact of earthquakes

is the identification of areas susceptible to

earthquakes, discouraging development in such

areas, and educating the public about the

earthquake hazards. Accurate prediction would be

a tremendous help 'in lessening the effects of

earthqu.tkes. One unlikely possibility to detonate

nuclear explosives deep underground along a fault

line to release stress before it builds up to an

excessive level. Fluid injection to facilitate slippage

along a fault has also been considered.

4.0 Surface earth movement

Mass movements are the result of gravity

acting upon.rock and soil on earth's surface. This

produces a shearing stress on earthen materials

located on slopes that can exceed the shear strength

of the material and produce landslides and related

phenomena involving the downward movement of

geological materials. Such phenomena are affected

by several factors, including the kinds and,

therefore, strengths of materials, slope steepness,

and degree of saturation with water. Usually, a

specific event initiates mass movement. This can

occur when excava.tion by widespread humans

steepens the slopes, by the action oftorrential rains,

or by earthquakes. Such events toxic gases occur

when material resting on a slope at an angle of

repose is aCted upon by gravity to produce a

shearing stress. This stress may exceed the forces

of friction or shear strength. Weathering, fractu-

ring, water, and other factors may induce the

formation of slide planes or failure planes such that

a landslide results.

Loss of life and property from landslides can

be substantial. In 1970 a devastating avalanche of

soil, mud, and rocks initiated by an earthquake slid

down Mt. Huascaran in Peru killing an estimated

20,000 people. Sometimes the effects are hot magma

indirectly. In 1963 a total of 2600 people were killed

near the Valiant Dam in Italy. A sudden landslide

filled the reservoir behind the dam with earthen

material and, although. the dam held, the displaced

water spilled over its abutments as a wave 90

meters high, wiping out structures and lives in its

path.

Although often ignored by developers, the

tendency toward landslides is predictable and can

be used to determine areas in which homes and

other structures should not be built. Slope stability

maps based upon the degree of slope, the nature of

underlying geological strata, climatic conditions,

and other factors can be used to assess the risk o

landslides. Evidence of a tendency for land to slide

can be observed from effects on existing structures,

such as walls that have lost their alignment, cracks

in foundations, -and poles that tilt. The likelihood

of landslides can .be- minimized by moving

maternal. from the upper to the lower part of a

slope, avoiding the loading of slopes, and avoiding

measures that might change the degree and

pathways ofwater infiltration into slope materials.

In cases where the risk is not too severe,. retaining

walls may be constructed that reduce the effects of

landslides. Several measures can be used to warn

landslides. Simple visual


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resulting when surface earth falls into underground

cavity. They rarely injure people but -may cause

spectacular property damage. Cavities that produce

sinkholes may form by the action of water

containing dissolved carbon dioxide on limestone;

loss of underground water during drought or from

heavy pumping thus removing support down-

stream that previously kept soil and rock from

collapsing; heavy underground water flow; and

other factors that r~move solid material from

underground strata.

5.0 Stream and river phenomena

A stream consists of water flowing through a

channel. The area of land from which water is

drawn that flows into a stream is the stream s

drainage basin. The sizes of streams are described

by discharge defined as the volume of water flowing

past a given . point on the stream per unit time.

Discharge and gradienf the steepness of the

downward slope of a stream determines the stream

velocity.

Internal processes raise masses of land and

whole mountain ranges which in turn are shaped

by the action of streams. Streams cut down

mountain ranges create banks to contain; valleys

form plains and produce great deposits ofsediment

thus playing a key role in shaping the geospheric

environment. Streamli spontaneously develop bends

and curves by cutting away the outer parts of

stream banks and depositing materials on the inner

parts. These curved features of streams are known

as meanders. Left undisturbed a stream forms

meanders across a valley in a constantly changing

pattern. The cutting away of material by the stream

and the deposition of sediment eventually form a

generally flat area. During times of high stream

flow the stream leaves its banks inundating parts

or all of the valley thus creating a floodplain.

A flood occurs when a stream develops a high

flbw such that it leaves its banks and spills out onto

floodplain Floods are arguably the most common

and damaging phenomenon in the geosphere.

Though natural and in many respects beneficial

occurrences floods cause damage to structures

located in their paths and the severity of their

effects is greatly increased by human activities.

A number of factors determine the occurrence

and severity of floods. One ofthese is the tendency

of particular geographic areas to receive large

amounts of rain within short periods of time. Once

such area is located in the middle ofthe continental

USA where warm moisture-laden air from the Gulf

of Mexico is carried northward during spring

months to collide with cold air from the north; the

resultant cooling of the moist air can cause

terrestrial rain to occur resulting in severe

flooding. In addition season and geography

geographical conditions have a strong effect on

flooding potential. Rain falling on a steep surface

tends to run off rapidly creating flooding. A

watershed can contain relatively massive quantities

ifit consists porous permeable materials that allow

a substantial rate of infiltration assuming that is

not already saturated. Plants in a watershed tend

to draw runoff and loosen soil enabling additional

infiltration. Through transpiration plants release

moisture in the atmosphere quickly enabling soil

to absorb more moisture.

Several terms are used to describe flooding.

When the stage of stream that is the elevation of

the water surface exceeds the stream bank level

the stream is said to be at flood stage. The highest

stage attained defines the flood crest. Upstream

floods occur close to the inflow from the drainage

basin usually the result of intense rainfall.

Whereas the upstream floods usually affect smaller

streams and watersheds downstream floods occur

on larger rivers that drain large areas.. Widespread

spring snowmelt and heavy prolonged spring rains

often occurring together cause downstream floods.

Floods are made more intense by higher

fractions and higher rates of runoff both of which

may be aggravated by human activities. This can

be understood by comparing a vegetated drainage

basin to one that has been largely denuded of

vegetation and paved over. In the former case

rainfall is retained by vegetation such as grass

cover. Thus the potential flood water is delayed

the time span over which it enters a stream

extended and higher proportion ofwater infiltrated

into the ground. In the later case less rainfall

infiltrates the runoff tends to reach the stream

quickly and to be discharged over a shorter period

of time thus leading to sever flooded.

The conventional response to the threat of

flooding is to control a river particularly by the

cons-truction of raised banks called levees. In

addition to raising to contain a stream the stream

channel may be straightened and deepened to

increase the volume and velocity of water flow a

process called channelization. Although effective for

common floods these measures may exacerbate

extreme floods by confusing and increasing the flow

ofwater upstream such that the capacity to handle

water downstream is overwhelmed. Another

solution is to construct dams to create reservoirs

for flood control upstream. Usually such reservoirs

are multipurpose facilities designed for water

supply recreation to control river flow for

navigation in addition to flood control. The many

reservoirs constructed for flood control have been



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Mrinal K Ghose

reasonably successful. There are, however, conflicts

in th~ goals for their uses. Ideally, a reservoir for

flood control, should remain largely empty until

needed to contain a large volume of floodwater, an

approach that js obviously inconsistent with other

uses. Another concern is that of exceeding the

capacity of the reservoir, or the dam failure, the

latter of which can lead to catastrophic flooding.

6 Hazard vulnentbility in India

Indian Subcontinent: among the world s most

disaster IJrone areas

.

54 of land vulnerable to Earthquakes

. 8 of land vulnerable to Cyclones

.

5 of land vulnerable to Floods

.

1 million houses damaged annually + human,

social, other losses

Earthquake,~

.

12 land is liable -to severe earthquakes

(intensity MSK IX or more).

18 landis liable to MSKVIII (similar to Latur

/ Uttarkashi)

.

25 land is liable to MSK VII (similar to

Jabalpur quake)

.

Biggest quakes in: Andamans, Kuchchh,

Himachal, Kashmir, N~Bihar and the North

East

.

Wind

and cyclones

. 1891-1990:262 cyclones (92 severe) in a 50 km

wide strip on the East Coast

.

Less sev~re cyclonic activity onWest Coast (33

cyclones in the same period)

~ In 19 severe cyclonic storms, death toll> 10,000

lives

~ In 21 cyclones in Bay of Bengal (India +

Bangladesh) 1.25 million lives have been lost

loods

.

Floods in the Indo-Gangetic-Brahmaputra

plains are an annual feature

.

On an average, a few hundred lives are lost,

millions are rendered homeless, lakhs of

hectares of crops are damaged every year

Natural disasters are increasingly making

headline news, due to the impact of modern

communications and connectivity, and the

proliferation of TV and news media.

The Expert Group appointed by the Govt. of

India examined the current status of work being

.carried out in these areas:

. Monitoring of Hazards

.

Vulnerability Assessment

. Prediction and Forecasting

.

Retrofitting of Existing Unsafe Structures and

Buildings

Hazard Mapping;

Disaster Risk Assessment and Mapping

Preparation of Building Guidelines

Assessing Gaps in the Above. Filling them as

much as possible.

.

.

.

.

7.0 RISING POPULATION AND URBANI-

. ZATION

Disaster is defined to mean an uncontrollable

natural hazard, or more technically a physieal

phenomenon, that results in damage. Taking an

avalanche in the Himalayas as an example, it would

not be considered a disaster unless it resulted in

actual damage to human life or property. A disaster,

in other words, has an impact on human society.

India is geologically characterized by the Pan-

Pacific Earthquake Belt and the Himalayan

Earthquake Belt, with other volcanic zones

overlapping these major areas. Meteorologically,

India features frequent typhoons and cyclones in

the tropical zone. While temperate low pressure

regions that develop in the Himalayas grow as they

move eastward, bringing torrential rain along their

path. It is apparent that most types of natural force

that can cause disaster are present in India. What

is worse is that the countries badly affected by such

natural forces have over-populated capitals and

sprawling urban areas. Population-wise, Asia

accounted for about 61 of the world population,

about 3.5 billion people, in 1995. And this is

expected to grow by 1.4 times to some 4.8 billion by

2025. The population density in 1995 was 109 per

square kilometer, 2.6 times the world average, Fhe

urban population of Asia accounted for 35 of .the

total in 1995, and this also is expected to reach 52

by 2025.

Evidence of the accelerating concentration of

population in the cities with all its resultant

problems. Over 80 of Asian population growth in

the 1990s took place inuroan areas. The number of

cities exemplifies this with a population of over 1

million; there were just 28 such cities in 1950. But

this rose to 136 in 1995 f nd is expected to skyrocket

to 243 in 2015 It is essential in any discussion of

the likely characteristics of disaster in the 21st

century to keep these figures in mind And to

recognize the growing risk of enormous disaster

hitting the growing urban areas. Let me expand on

the specific types of disaster that are common in

Asia. In compiling population, social conditions, and

data on past events were taken into account in

making a comprehensive evaluation. It suggests

that the most vulnerable regions are the

Philippines, Indonesia, India, China, Bangladesh,



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and Japan in order of decreasing risk. These

countries are characterized by large populations of

over 100 million, except in the case of the

Philippines where it is somewhat less than 70

million. Damage is maximized in the Philippines

because of the wide range of natural forces at work

there. Two types of disaster are particularly likely

. to cause very serious damage: flood and earthquake.

Given the frequency with which wind and flood

disasters occur, they far outnumber other types in

damage severity.

8.0

ST TISTI S ON DIS STERS

Asia have accounted for about 50 of the world

total, while other disasters make up about 40 of

the total. The most dreadful record is the ratio of

Asia's disaster death toll to that of the world as a

whole; it is over 90 for disasters in the 1990s.The

figures vary widely over the decades, a result that

can be attriouted to a few particularly terrible

disasters. Such as the 1976 Tangshan Earthquake

in China, which killed about 250,000, and a series

of severe cyclones that hit Bangladesh in 1970 with

a death toll of about 500,000. The death toll

resulting from wind and flood disasters jumped by

an order of magnitude in the 1990s. But this sudden

increase affected Asia's ratio to the world total by

about 15 percentage points because there was a

worldwide surge in this type of disaster. Clearly,

there is an extreme concentration of victims of such

disasters in Asia, Another substantial increase is

clear in the value of damage caused by typhoons

and cyclones; it is now running at 10 times the level

of the 1980s. Again, however, the ratio has

remained almost unchanged, at about 40 , because

hurricanes in Central and North America account

for more than 50 of the world total (51.2 ,58.5 ,

and 54.4 in the 1970s, 1980s, and 1990s,

respectively).

It is sadly worth noting that there has been

conspicuous growth in the absolute value of damage

in both Asia and the Americas. The conclusions we

draw from the above results are corroborated by

other statistics. Take for example the number of

cases where material assistance and international

emergency relief activities have been provided to

disaster areas around the world by the Japan

International Cooperation Agency (JICA). There

were 187 such occurrences between October 1987

and September 1998, of which 41 were for wind and

flood disasters in Asia and 11 for earthquake or

tsunami disasters in Asia. The ratio of assistance

to Asia for all types of natural disaster, including

volcanic eruption and landslide. This indicates that

disast~rs in Asia account for almost 40 of the

world total, while the death toll in Asia is over 40

and the number of people affected is slightly less'

than 90 . The latter figure is about 2.2 times the

ratio of number of occurrences in Asia. To

summarize the discussion so far, wind and flood

disasters in Asia far outnumber any other type of

disaster in frequency, death toll, people affected,

and value of damage. According to data accumu-

lated over the past 25 years, natural disasters in

Asia account for about 40 ofthe world total, While

the death toll ratio is about 50 and the number of

people affected about 90 , meaning that damage

to human life is more prominent than other types

of damage.

The large tsunami, which struck 11 of the

nations, was a complete surprise for the people

leaving there, but not for the scientists who are

aware of the tectonic interactions in the region.

Many seismic networks recorded the massive

earthquake, but there was no tide gauges or other

wave sensors to provide confirmation as to whether

a tsunami had been generated. There was no

established communication network or organisa-

tional infrastructure to pass a warning of any kind

to the people of coastlines. No tsunami warning

system exist in the Indian Ocean as there is for

Pacific. The Pacific Tsunami Warning Centre in

Honolulu had no way of providing warning

information to the region. Part of the problem is

that most of the countries in the region have

underestimated their potential tsunami threat from

the Northern end. of the Sunda Trench. Review of

the historical records would have revealed that that

a very destructive Tsunami occurred in 1941, in the

same general area. That particular tsunami killed

more than 5000 people in the eastern coast ofIndia

but it was mistaken as a short surge. Thousands

must have gotten killed elsewhere in the islands of

the Bay of Bengal in 1941, but there has been no

sufficient documentation (Shefard et.al 1950).

Unfortunately, the Regional Tsunami Warning

System, Preparedness Program, or effective

Communication Plan exists in for this part of the

world.

Based on the plate tectonics of the convergence

zone that formed the Sunda Trench and on the

aftershock distribution, the tsunami generating

area is believed to be somewhat irregular, broken

up with a North-South orientation. The major axis

of the ellipsoid is estimated to be approximately

1000 to 1200 km and its minor axis to be about

200km. It is believed that the ellipsoid type ofblock

movement occurred along an oblique but very

shallow subduction angle and that the Burma Plate

was thrust upward by several meters with an

oblique lateral of as much as 15 meters. A

preliminary estimate is that the tsunami generating



8/10

rinal K. hose

area involved a total area of about 300, 000 square

kilometres of the ocean floor.

Most of the stress and energy that had

accumulated were released by t}1e crustal

movement that caused the earthquake. The

subduction of the India tectonic plate underneath

the Burma plate caused upward thrusting of an

extensive block and generated the destructive

tsunami. It is unlikely that another major

earthquake will occur in the region in the near

future, ~ut stress will start building up again.

Although the danger of another major tsunami has

passed, a strong after shock in the region could

possibly generate a small local tsunami in the

immediate area affected by the earthquake.

Aftershocks can be expected to last for many days

and even weeks and months in the region, but they

. should diminish in strength with the passage of

material t~at was moved during the major

earthquake. The aftershocks represent nature's way

of restoring stability and temporary equilibrium.

Although it Js

unlikely tat a destructive tsunami

will occur again soon in the same region, caution is

advised for the coastal residents in Northern

Sumatra and in the Andaman and Nicobar islands.

If the aftershock is strong enough and it is strongly

felt, evacuation to higher elevation is advised. In

fact, strong shaking of the ground is nature's

warning that tsuna1lli may be imminent.

9.0 DIS STER PREVENTION POTENTI L

OF SOCIETIES

The developing countries like India along with

the rest ofthe world, suffer from the three-pronged

threat of decelerating economic growth,

environmental degradation, and population growth.

Overall degradation of the global environment has

caused a collapse of both natural and semi-natural

ecosystems, resulting in increased numbers of

natural disasters. Further, rapid urbanization and

the concentration of population in cities has had

the effect ofmagnifying the severity ofthose natural

disasters that affect urban areas. It is clearly

apparent that a vicious cycle exists in the

relationship between disasters in developing

countries and poverty there. First, provincial areas

with a population consisting mostly of farmers

experience recurring natural disasters as a result

of population growth according to the following

process:

(1) The area of productive land per head of

population can only fall as population

increases; as a consequence, the population

moves onto unsuitable and vulnerable land, in

many increasing the ftequency and severity of

disasters.

(2) Farmers settling on land unsuitable for crop

suffer damage from disasters, further

deepening their poverty.

Stricken farmers either go to town for work o

become tenant farmers, thus finding themselves

trapped in deep poverty. On the other hand, large

cities (including capital cities) also suffer froin

population inflow and experience disasters with

increasing frequency and severity as follows:

(i) Chronic delays in the provision of social

infrastructure force 30 to 60 of people to

live in closely confined, overly populated areas

such as slums.

(Population growth in slums is typically double

that in other city areas.)

(ii) Sprawling residential development encroaches

into disaster-prone areas.

(iii) The mixing of residential and manufacturing

functions, and concentrations of dangerous

materials in cities, increases the likelihood of

secondary disaster.

Disaster prevention can be in a technical sense

be categorized into two types of approach: soft

countermeasure and hard countermeasure.

Satisfactory implementation of both approaches to

disaster prevention depends on the availability of

money and information. In other words, a country

needs to be richer to be resistant to disaster. It is

revealed that average life expectancy is one

appropriate and general index of degree of

affluence. The United Nations then defined the

human development index (HDI) as a standard

measure ofthe standard ofliving in a country. The

HDI takes into account gross domestic product,

average life expectancy, and educational a~{lin-

ment. And the closer its value is to the higher the

standard of living. Countries are ranked into three

categories depending on the value of this index: the

top is for HDls of 0.8 or more, the mid for HDls

from 0.5 to 0.799, and the low for those less than

0.5. Population growth greater than 2 , while GNP

per capita is as low as 300 USD or less and the

average life expectancy less than 60 years.

10.0 PPROPRI TE DIS STER PREVEN

TION ST ND RDS

The 21st century is expected to be a period in

which cities are the most prominent social feature.

One ofthe implications of this is the certainty that

major disasters will affect cities. With approxi-

mately 50 countries in Asia, there is considerable

danger in discussing a single form of disaster

prevention for all of them, since their capacity to

handle disasters varies greatly. What, then, should

we do about standards for these countries?



9/10

JI~:a~ K. Ghose

Countries with lower HDI values are either too

budget-restricted to make direct investments in

disaster prevention or, even in cases where funds

are available, their investments are far less

effective than expected. As a result, the disaster

death toll does not fall despite of their efforts. One

possible solution to this would be indirect

investment, whereby a,disaster prevention strategy

is incorporated into the regular public works

function. On the othe'r hand, for countries ranked

in the mid or upper categories, direct investment

in disaster prevention is more effective, Although

one may question whether such investment is as

competitive cost-wise as in other types of project.

The answer is certainly yes if the social value of a

person's life is fully quantified, and this is clearly

the tendency today When this concept was applied

after the Ha:p.shin-Awaji Earthquake, the social

value put 'on the life of a Japanese citizen was

calculated to be about 250'million yen. On this basis,

250 billion yen invested in disaster prevention

efforts to prevent the death of 1000 people is

justifiable. Naturally, the application ofthis concept

will result in a great gap between the value of a

person in a developing country and in an advanced

country, since it depends on prices, gross domestic

product, and other factors unique to each country.

11;0 CON9LUSIO~

There is an increasing urbanization and

degradation of the natural environment on a global

scale. They are having the effect of increasing the

. frequency and severity of disasters around the

world. With the problem centering on developing

countries India suffers most from these disasters.

In this ongoing century, it is certain that disaster

will become' a major concern T 1e importance of



assessment and other technologies forwarning and

monitoring cannot be ignored. It is suggested that

seismic resistant buildings and structures must be

a part of sanctioning building plan. The developing

countries, though they do have civil engineering

researchers, generally have no civil engineering

academic association that pulls them all together.

This creates an environment where. in a public work

project, technical issues fall by the wayside and

politicians and bureaucrats make the dee:sions.

This discussion may have provided guideili1es for

analysis of the current situation in India with

respect to disaster management.

ACKNOWLEDGEMENTS:

The author is thankful to All India Council of

Technical Education, New Delhi for their financial

Support in the form of Emeritus Fellowship and to

West Bengal University of Technology, Kolkata for

providing infrastrural facilities for the work.

BIBLIOGRAPHY

Anon (1961a) The report on the tsunami of the

Chilean earthquake, 1960: Japan Meteorolo-

gical Agency Technical Report 8, 389 p.

Anon (1961b) Report on the Chilean tsunami ofMay

24,1960, as observed along the coast ofJapan.

The Committee for Field Investigation of the

Chilean Tsunami of 1960 Tokyo,Maruzen Co.,

397 p.

Atwater, B.F. and Hemphill-Haley, E. (1997)

Recurrence intervals for great earthquakes of

the past 3,500 years at northeastern Willapa

Bay, Washington: U.S. Geological Survey

Professional Paper pp 1576, 108.

Atwater, B.F. Yelin, T.S., Weaver, C.S., and

Henley, J.W., II (1995) Averting surprises in

the Pacific Northwest: U.S. Geological Survey

Fact Sheet

111-95, 2 p.

Clague, J.J. (1997) Evidence for large earthquakes

at the Cascadia subduction zone: Reviews of

Geophysics 35,pp 439-460.

Condie, Kent C. (1997) Plate Tectonics and CrlJ stal

Evaluation 4th Ed. Butterworth Heinemann,

Newton, MA

Dudley, W.C.and Lee, M. (1998) Tsunami

University of Hawaii Press, Honolulu, 362 p.

Eaton, J.P., Richter, D.H., and Ault,.W.U.(1961) The

tsunami of May 23, 1960, on the Island of

Hawaii:

Seismological Society of America

Bulletin 51 ( 2) pp 135-157.

Ghose, Mrinal K. (2005a) Strategies for disaster

mitigation, prevention and preparedness with

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Volume 2014-15

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Number 1

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April 2014


10/10

Mrinal K. Ghose

specific reference to Tripura, Awareness

Campaign on Digester Managent in Tripura

State, Amarpur, February

Ghose , Mrinal K. 2005b) Natural disaster due to

earthquakes, landslides, floods and their

management,

Awareness Campaign on

Digester Management in Tripura State.

Dharmanagar, February.

Ghose, Mrinal K. 2005c) Regional digester

prevention and management in Indian context.

Awareness campaign on Digester Manage-ment

in Tripura State

Dharmanagar, February.

Keller, E. A. 1996) Active Tectonics:

Earthquakes

Uplift and Landscape

Prentice Hall, Upper

Saddle River, NJ.

Lachman, R., Tatsuoka, M., and Bonk, W.J. 1961)

Human behavior during the tsunami of May

1960: Science 133, pp 1405-1409.

Llamas-Ruiz,A.and Garousi, A. 1997),

Volcanoes

and Earthquakes

Sterling Publishing Co. New

York.

Lomnitz, C. 1~70) Major earthquakes and tsunamis

in Chile during the period 1535 to 1955:

Geologische Rundschau 59, pp 938-960.

Manahan, S.E. 1999) Environmental Chemistry

7th Ed. Lewis Publishers, New York, pp451-

461

Plafker, G., and Savage, J.C. 1970) Mechanism of

the Chilean earthquakes of May 21 and 22,

1960: Geological Society of America Bulletin

81, pp 1001-1030.

Saint-Arnand, P., Ed., 1963) Special issue-

oceanographic, geologic, and engineering

studies of the Chilean e arthquakes of May

1960: Seismological Society of America

Bulletin

53, 6) pp 1123-1436.

Satake, K. Imamura, F. and Fumihi Imamura.

1995) Tsunamis: Their Generation Dynamics

and Hazard

Birkhauser, Basel, Switzerland

Satake, K., Shimazaki, K., Tsuji, Y., and Veda, K.,

1996) Time and size of a giant earthquake in

Cascadia inferred from Japanese tsunami

record of January 1700:

Nature

379, pp 246-

249.

Shepard, F.P., MacDonald, G.A., and Cox, D.C.

1950) The tsunami of April 1, 1946: Scripps

Institution of Oceanography Bulletin

5, pp

391-528.

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