Earthquakes

15
EARTI{QUAKES
E*ent of eart\uate
d-n-ges
The Indian subcontinentsituatedon the boundariesof trvo continentalplatesis very prone to earthquakes.All five
SAARC nations --- India, Pakista4 Nepal, Bhutan -6 gengladesh-- who have the Himalayan range as their
boundary or are in close proximity to it, have a long history of seismictremors. In Maldives and Sri l,anka, there is
no record of any disastrousearthquakes,though some incidents of seismic activity have been noted in the records
of the former's National Centre for Historical and Linguistic Research.However, these two countries arc generally
consideredearthquakefree.
Massiveearthquakesgenerallyoccur near the junction of two crustal plates,for example,along the Himalayan renge
wherethe Indian plategoesbelowthe Eurasianplate.This is the commonestform of earthquakes,known as tectonic
earthquakes.The other forms being volcanic eart\uakes, impact earthquakes(due to the impact of meteorites),
reservoir induced earthquakes,and collapseearthquakes.Someof thesehavealso been found in the SAARC region.
Earthquakesare responsiblefor the loss of about 50,fi)0 lives every year in the world. Loss of property in a single
earthquake is some times enough to upset a whole national economy.The intensity of an earthquake is measured
on a 10point scaleoriginallydefinedby Richter in 1958.Earthquakesover5.5are progressivelydamagingto property
and human life.
Pakistanoccasionallyfalls victim to earthquakes.Quetta city was completelydestroyedby an earthquakein 1935and
30,000personswere killed. The epicentreof the earthquakewas very near Quetta and its intensity was7.2 on the
Richter scale.As regards the history of earthquakesin the country no reliable information about their (rccurrence
before 1933is available.The onll historical evidenceis about Debal city that was destroyedin an earthquakein 893
A.D. Sayuti in Tehrikh-e-Khulfa has given complete details of the calamity.Another tremor which causedextensive
in the land surfacetook placein the Rann of Kutch in 1819.During 1845-1861,
sfuanges
not lessthan sevenshocks
of low intensity were recorded in the Karachi region. In 1931,parts of Baluchistan and Sindh experienceda shock
of the magnitude of 8.3 on the Richter scalewhich lasted for about 30 seconds.The Makran earthquakeof 1945also
causedwidespread damage.During I955-L970,shocksof varied intensity were recorded in different parts of the
Pakistan.
The recent 191 earthquakewhich ravagedthe northern parts of the North West Frontier Province (NWFP) was less
disastrousthan the 1973Beshamearthquakewhich claimed5,000livesin Kohistan dbtrict. Though the intensityof
Beshamearthquakewas only 5.6 on the Richter scaleas comparedto 6.8 of the 199Learthquake,the damagesand
casualtieswas far less. The causeof large-scaledestruction n L973was becausethe area of Besham is rocky and
mountainousand becausejolts are usuallymore intensein mountainousregions as compared to the plains.ln 1973,
many villages and housesin Besham were razndto t\e ground as big rocks rolled down from the nearby mountains
and landslidesdestroyedthe villages.
Approxinately 10,000earthquakeshavebeen accuratelyrecorded within a 400 sq k- by 500 sq km area in northern
Pakistan.The data collectedby Water and Power DevelopmentAuthority and PakistanAtomic Energ5rCommission
include earthquakes of magnitudes 6 to 2. They reflect the high seismicity of the regioq which includes the
northwestern e:ffemity of the Indian plate, the Salt range, Potwar plateau" Hazara range, Peshawarbasin and the
lower and higher ranges of Indus Kohistan. Seismicactivity in the Hazara range is betr*,eenmoderate to high and
earthquakes here have caused oftensive damage. The Salt range has no known history of moderate or large
earthquakesbut, at low levels, the entirg Salt range is active, especiallyalong the long transversefault. The other
regionsof major seismicactivity in Pakistanare the Mir-Karakoram region, the Gardez, Kumar and SafedKoh fault
zones, the Chaman fault zone, the Ornach-Nal fault zone, the Sulai-an range, the Quetta transverse zone, the
northern and southernKirthar ranges,the coaptalregon southeastof Karachi"the Murray Ridge, the Makran region
and the Indus basin.
According to the Meteorological Upper Atmosphere ResearchStation in Peshawar,100,(m earthquakesof low and
high intensity occur everyyear in the Hindukush area.The Hindukush range is about 1,613km miles long and about
323 km wide running northeastto'southeast.The range ru"* througb Pakistanbefore entering Afghanistanand
fragmentinginto minor ranges.Theserangesare the main sourceof earthquakesthat jolt the NWFP and other parts
of Pakistanat regular intervals.During the recentearthquake,MalakandAgencyand Division,which are very close
to the Hindukush mountains,sufferedheavylossesas comparedto other parts of the country.
India has also not escapedmajor earthquakesthough accuratefigures are not available about monetary loss caused
by these earthquakes.Table 15.2 gives a list of the lives lost in some major earthquakesin India. India has been
divided into five seismic zones according to the maximum intensity of earthquakesexpected.Of these, Zone V is
seismically the most active, while Zone I is the least active. Tnne Y comprisesthe whole of northeast Indiq the
northern portion of Bihar adjoining Nepal, west Uttar Pradeshhills, Hinachal Pradesharound Mandi, Rann of
Kutch, and Andaman and Nicobar Islands. Tnne IY includes Himachal Pradesh"Delhi, parts of Punjab, Uttar
Pradeshand Bihar, Sikkim and adjoiningWestBengat a smallportion near Calcutt4 Maharashtranear Kolma(south
of Bombay), and a part of Gujarat. Znnelll comprisesls6eining portions of Punjab and a small part of Rajasthan,
Uttar Pradesh,Madhya Prades\ Bihar and adjoining West Bengal, Gujarat and Maharashtra and a small portion
parallel to the west coast of peninsular India, a very small portion of Karnataka and Andhra Pradesb, and
l"akshadweep.Tnne II includesTamil Nadrr,parts of Karnatak4 Andhra Pradesh,parts of Maharashtra, Rajasthan,
Uttar Pradesh,Madhya Pradesh,Bihar, Orissaand West Bengal.Tnne I comprisesls6eining parts of Karnataka,
Andhra Pradesh,Maharashtra,Oriss4 Rajasthan,MadhyaPradeshand Uttar Pradesh.
Nepal lying on the southern slopesof the Himalaya is subjectto high seismicactivity. A chronolog5rof earthquakes
of magnitudessixhnd aboveon the Richter scaleindicatesthat beween 1800and 1975,23 major earthquakeshave
occurred in Nepal. Earthquakesof lower intensity occur frequently especiallyduring the rainy season.
Observationssuggestthat large earthquakesoccur aboutoncein 50 years.There havebeenthree major earthquakes
in the last 55 years.The 1934earthquakewhich affectedBihar and Nepal destroyed3,400lives in Kathmandu valley
alone.In 1980,the areaof Bajhangin westernNepalwasstruckby a powerfulearthquakein which manypeopledied,
and considerablepropertywas lost. On August 21,198f,,an earthquakeof m"gnitude 6.6 on the Richter scale,with
its epicentre at Udaipur in easternNepal, killed 7L7 people and destroyedseveral thousand houses.
The principal fault lines in the Nepal Himalaya are the transverseMain Central Thrust and the Main Boundary
Thrust. However, aside from these,there are many longitudinal faults which divide the Hinalaya into "blocks"from
eastto west.The epicentreof major earthquakesare often locatedalong thesefault lines.Most of the earthquakes
between 1964and 1986have been clustered in western Nepal.
Bhutan $ng in the northeasternpart of the Himalayan belt has a high seismicityrate. Earthquakes of magnitude 7
to 7.5on the Richter scalehavebeenrecordedin the country.Areas adjoiningBhutanhaveexperiencedearthquakes
more than 8. The seismiczoningmap preparedby the Indian StandardsInstitution doesnot coverBhutan but from
the studyof the seismiczoningmap of adjoiningareas,the entire countrycan be taken to be within seismiczone V
correspondingto the highest seismiczone of India.
Bhutan,however,has not been hit by any major earthquakein the past.The mosl recentearthquakewhich affected
the country in August 1988causedonly minor crack on the TashigangDzong. In view of the fact that the past few
earthquakeswhich hit the country had not been major ones and had caused only slight damagesto structures,
earthquake disastermanagementhas not been a priority for the government.No infrastructure specifically charged
with earthquake managementhas been set up. Nevertheless,the governmentenforces strict building specifications
which take into account the seismicityof the country.
Bangladesh,particularly the northeastern region, has in the past experiencedearthquakes of moderate to high
intensity. The great earthqmke of 189, which had its epicentre in the Shillong plateau of India, causedwidespread
damage.Two other major earthquakes,the Bengalearthquakeof 1885and Srimangalearthquakeof 1918,caused
severeda-ages in limited areassurrogndingtheir epicentres.
B*ngtadeshon the east€rnflank of the Himalayanfoothills hasbeen dividedinto four seismiczones.The north and
northeasternpart including Sylhet,Mymensingband Rangpur towns are in Zone 1, which is the most active zone of
the country. Dinajpur, Bogrc T-g"tt" Dhaka, Comilla and Chittagong Hill Tracts fall in Zone 2, where the shocks
are moderate. Rajshahi, Pabna"Faridpur, Noakhali, Chittagong and Co:CsBazar, where minor shocksoccur, are in
includingJessore,Khur.a, Barisaland Patuakhali,fall in Zone 4 where
Tnne 3. The southwesternpart of Bangladesh,
negligible shocls are observed.
Danragemidgntim meiesures
When earthquakesoccur major disasterstake place.Buildingscan collapse;Frresmay be induced;floods may occur
and landslidestake place;tidal waveson coastal
due to collapseof damsand protectiveworks on rivers;avalanches
r77
belts can occur; hazardoussubstancesand gasescan be released;and essentialserviceslike water supply, electricity,
sewagesystems,communicationlines,31d 6ensportc:" be disrupted.The major factor contributingto both economic
and human loss is the collapsesf guildings during earthquakes.
Earthquake forecastingis a relatively complex task. It eimg 4t forecastinglocation, time and mrgrritude of an
impending earthquake.A network of 56 seismographicstationshas been set up in India and more are being planned
under the jurisdiction or coordination of the India Meteorological Department (IMD) which measuresdailyseismic
activity parameters,namely, velocity of prinary and secondarywavesand micro-earthquakesover the point where
the instrumentis set.Apart from theseparameters,variousother ground paremetersare also taken into accountfor
prediction purposeslike crustal deformation; chengein seismicwavevelocity due to stressesin rocks; large decrease
in magnetic susceptibility of rocks just before earthquakes;and, changein electrical resistivity of rocks. Sea level
changeshavebeen noticed prior to the occurrenceofan earthquakeand so hasunusualbehaviour ofcertain animxls,
particularly fishesand mammals.Dogs hanebeenseenhowling and chimpanzeeshavebcen seento spendtheir nights
on the ground rather than on trees a few days before the occurrence of an earthquake. The behaviour of these
enimals can probably be monitored for a rough estimate of the onset of an earthquake. These parameters are
empirical and no constant factor has besn found to predict accuratelythe occurrenceof earthquakes.
Although no definite researchfinding is available on the most suitable e"gl"eering structure f61 fuildings situated
in active seismicZOtr€Se
the Governnent of India has issuedguidelinesregarding construction of buildingsand other
e"glneeringstructuresfor the statessituatedin seismiczonesIV and V. The salientpoints of theserecommendations
are that buildings and structures in earthquake zones should be strengthened and retrofitted against future
earthquakes.For this purpose,appropriate technicalguidancewill be provided by the Earthquake Reslarch Centre
of the Roorkee University and by the Department of Agriculture and Cooperation. Rural buildings and structural
designsshould be built al p€r the existing rural housingschemetn Tnne V. The Housing and Urban Development
Corporation has been askedhelp in the evaluationof suitable designs.In north Bihar, special cells are to be created
in Darbhanga,Madhubani,Monghyrand other districtsto coordinatework on strengtheningof build;'F".An institute
for the study of seismicphenomenain northeasternstatesis to be set up and the inginsering departirents of these
statesare f6ing encouragedto developearthquakeresistant designs.Municipal bylaws for building construction for
cities in zones IV and V are being suitably arnendedto incorporate earthquake resistant construction features. A
seismiccode which is meant to outline the stepsnecessaryin the eventof earthquakes,so as to minimise damage
to life and property, is to be drawn up.
The basic responsibility for undertaking relief and rescueoperationsis of the state government. In caseof a severe
disaster, the Union Government provides frnancial and material support. The Department of Agriculture and
Cooperation is the nodal department.The relief commissionerfunctions as the nodal officer, who liaises with
ministriesand departmentsthrough the Crisis ManagementGroup (CMG). The relief qommissioneris responsible
for senditg centralteemsto the affectedstatesfor assess;ng
danage.In the states,the staterelief commissioner(or,
in his absence,the secretary,revenuedepartment) is the nodal point for rescueand relief operations.[n seriougcases,
the stategovernmentmay also form a group of cabinetministersto overseerelief anrl rescueoperations.
However, it is at the district level that all relief and rescueoperationsare actually implemented.The district collector
is overall in charge of relief and operations, who is assistedby revenue officers as well as other departments and
agenciesat the district level. Every district is responsiblefor drawing up a district contingencyplan for timely action
in case of earthquakes, in seismically active zones. The contingency plan involves three tlpes of aciioos -preparedness,actual relief and rescueoperations,and rehabilitation. The preparednessphaseinvolves coordination
with IMD seismologicalobselvatoriesstationsand All India Radio and Doordarshanfor advancewarning whenever
possible.Evacuationcentreswith strongly built structuresare eannruked for people in areas likely to bJaffected by
earthquakes.However, in most cases,relief and rescue organisationshave no prior intimation about impending
earthquakes.
The stress,therefore, is on actual relief and rescueoperations -- phpical evacuation of people trapped in debris,
establishmentof alternate me.ns of mobile comrnnnications,and construction of temporary bridges, culverts,
provision of medical facilities, supply of food and other nutritional requirements. Voluntary and charitable
organisationsalso help in theseoperations.Rehabilitation of affectedpeopleis a time consumingpr@essand involves
strenuousrebuildi"g of the collapsedstructureg restoration of communications,provision of cashrelief to the affected
people, employm.entgeneratio& and restoration of the ecos)4stem
etc.
In Nepal, the seismologicalcentre of the Department of Mines and Geology operates a network of Frveseismic
stations clusteredin the central developmentregion. However, a network of 15 to 20 stations are required to
accuratelyrecord quakesof lower intensity.Extensivetime seriesdata is indispensablefor seismiczoning and for
preparingvulnerabilityprofiles.
According to a study of the consequencesof earthquakesin Nepal" the August 1!)88(Udayapur) earthquake'which
wasof a moderatecategory,left6,63 injured, of which 1,68 werc serious.A total of 63,003buildinSswere damaged,
of which 2!,832werc totally destroyed.A total of 1,483headsof cattle were killed. The study pointed out that damage
to ordinary buildings and structures wursfar more than to RCC structures which appeared to have withstood the
shocksmore effectively.Ground fissuring was prominent. I-andslidesin the Churia and Mahabharat Range affected
an area of 0.62 million hectare. Thesehad seriousconsequencesfor the stability of irrigation canals,and roads and
trails. In someportions of the Terai regon, the earthquakecausedliquefaction in subsurfaceground layers and sand
boils. This extensivedanage causedby a relatively mild earthquake indicates an overall lack of preparednessfor
facing such exigencies.
The Earthquake Affected Areas Reconstruction and Rehabilitation Project (EAARRP) was launched after the
earthquakeof 1988.The Department of Housing and Phpical planning initiated a programme of rehabilitation which
in the desip sf $uildings and other infrastructures.However, the implementation of the
will also introduce qfuenges
programme has been obstructed by financial constraints.Under the Natural Calamities Relief Act of 1982and the
Soit and Watershed ConservationAct, eight long term plans and a Natural Calamities AssistanceFund have been
established.
Considerablefinancial and technical aid has been received from e:rternal donor agencies.The major focus of the
assistancehasbeeir on rehabilitation and reconstruction.Severaldonorshavealsobeen involvedin integrated sectoral
progam6ss and income generation activities in the affected areas. UNDP has initiated a long term technical
u..irtao"" progrrrnme to formulate a national building code, and to introduce improved building materials and
constructiontechniques.The agencyis also aiding Nepal in enhancingits level of preparedness.One outcome of this
assistanceis going to be a national housing strategy.
In Pakistan, identification of seismic zones is done by the Geological Survey of Pakistan. The GSP regularly
undertakessurve)6 and researchto monitor changesin earthquakeprone areas.In 1976,the Geologicd Survey of
Pakistan and the National ScienceFoundation of USA, started the Geodpamics of Pakistan Project which has
providedPakistaniearth scientistswith an opportunity to expandtheir knowledgeabout the geodynamicsof their land.
The project has led to a better understandingof the geodynamicsof Baluchistan.
Building codes prepared by the Environ-ent and Urban Affairs Division provide specificationsfor the design of
earthquakeresistantbuildings.The building regulationsformulated by urban developmentauthorities are specificand
safetymeasuresare ensuredin everybuilding. There are specialrules for high rise buildinp. In rural areas,however,
these specificationsare rarely followed.
The government's emphasis is on connecting far-flung areas with the national road network and modern
communicationsystems.Relief work is often delayedbecauseof the absenceof a road and communication link with
affected areas.Accessto remote areasduring heavysnowfall or bad weather becomesimpossible.Establishmsnt of
basecampsin aboveareasfor relief operation is an important work done by the government.No arrangementshave
so far been made for fire outbreaks. In urban areas,nunicipalities have arrangementsfor fire fighting. But in the
remote mountain settlementswhere earthquakescausedevastatingdem&ge,evacuation,relief work, fire fighting and
rehabilitation is done with the help of armed forces. Emergency plans are prepared both by provincial and local
authorities. Evacuation centres are establishedand with the help and assistanceof other departmentsand agencies,
supply of food and water and arrangementsfor prevention of epidemicsare made. The armed forces play a crucial
role in all these arrangementsin Pakistan.
On December 2l!, 19'l,4,an earthquakeof mrgnitude 6.0 occurred in the remote and barely accessibleregion of Swat
and Indus Kohistan, south of Hindukush and Karakoram rangeof mounteins.Severalthousandpeople died and some
60,000to 100,000were affected.The Karaftoran highway,which was at that time under construction and renovation,
wasvery badly danaged and was unusablethroughout most of the relief operation. Helicopters were usedto Pattan,
where a hospital camp was establishd even though the village was very badly damaged.
Perceptims of strcngtts and wa&nesses
The Government of India feels the need to develop an integrated large scale warning s'rstemfor earthquakesto
6inimise the impact of earthquakesin future. Although a large number of paremctcrs are being monitored,
integratedresearchis still neededto developearthquakeforecastmodelsfor accurateforecasting.
In Nepal, too, an increasein the scientific capacity for monitoring seismologicalevents is consideredto be
indispensable.As a first step, the number and distribution of seismologicalstations must be increasedto cover all
the regionsof the country. Considerablescientificwork is required to delineateseismiczonesbefore any level of
179
accuracyin earthquakeforecastingand modelling can be achieved.The current data baseis both poor and extremely
unreliable. On the organizationalfront, a programmeto integrate the work of numerous governmeDtand private
agenciesis needed.
The governmentfeelsthat infrastructure developmentactivitiesmust conform to universallyacceptedstandards.euick
responsemeasuresfor relief and rehabilitation needto be establishedat the national level. UNDP assistanceto Nepal
is expectedto contribute substantiallytowards ameliorating severalof these deficiencies.
Earthquakesof low intensity occuu'elmost every week or month and severeearthquakesalso occur occasionallyin
Pakistan.There is, thug a need for earthquakemanagementto be strengthenedin Pakistan.
Table 15.1
Significant eattbquates of intensity greater than 6.0 m thc Rkhter scah in atrd aroud Bang|dcsh (1951 wards)
Date
Origin tine
Epicentre
Magnitude
h.
m.
s,
"N
"E
(Richter scale)
06.03.1951
18
58
13.5
?4.8
95.1.
6.4
L2.03.r95r
L4
52
17.2
28.2
94.5
6.5
ut.M.rgsr
m
29
L2.4
8.8
90.4
6.8
14.04.1951
A
4
49.4
28.2
94.r
6.4
23.02.L954
06
4
32.0
n.8
9t,7
6.25to
6.5
2r.03.1954
23
42
L7.0
24.2
95.1
7.25
0L.07.t957
19
30
22.0
24.4
93.8
7.25
22.W.1%2
06
51
32.3
?5.5
97.0
6.25
L2.07.L9&
n
r
59.0
24.9
95.3
6.7
12.01.1%5
L3
32
24.0
n.6
88.0
6.1
Table L5.2
Lives hst h sme naja eart\uafes in South Asia
Place
Loss of lives
Kangra
(1e0t
?n,m
Bihar & Nepal
(1e34)
10,000
Quetta
(1e3s)
(1e50)
60,000
Assam
?6,m
180
Table 15.3
Pereptims of strengths and *taknesses
Bangladesh
1.
SeigmologicalStation 1 No.
Project for 3 stations are under
consideration
L.
,,
1.
)
Lack of study,researchand monitoring
Lack of organisational infrastructure
NA
NA
Bhutan
India
Weatnesscs
Strengths
CJmtry
stations
A network of 56 seismographic
have been set up
Guidelines for appropriate building
structures for different seismic zones
has been provided
1.
2.
Lack of integrated large scale warning
s)4stem
I"ack of integrated research and
accurateforecasting models
Maldives
Nepal
1". Mapping of Active Fault Zones
1.
2.
3.
4.
5.
6.
Pakistan
Sri Lanka
Inadequate number and poorly
distributed seismologicalstations
Inadequatescientificcapacityto monitor
seismologicalevents
Poor and unreliabledatabase
Lack of integration betweennumerous
government and private agencies
Inadequateorganisationalinfrastructure
Slow responsemeasuresto relief and
rehabilitation
NA
NA
1. Recording capability
MeteorologicalDepartment
NA : Not Available
181
with
1.
Defunct recordinginstrument