CONTENTS
PART-I: SEISMIC MICROZONATION OF COXS BAZAR MUNICIPAL
AREA---------------------------------------------------------------------------31
PART-II: EARTHQUAKE VULNERABILITY ASSESSMENT AT
OLD DHAKA (WARD NO.68)------------------------------------------123
111
PART-III:STRONGMOTIONMONITORINGSYSTEMSIN131
BANGLADESH: 2007 TO 2009-----------------------------------------148
PART-IV: GEOPHYSICAL SURVEYS AT SRIMANGAL AREA,
143
SYLHET---------------------------------------------------------------------160
PART-V: ANALYSIS OF CLIMATE CHANGE PHENOMENA IN
163
BANGLADESH------------------------------------------------------------180

177
PART-VI: WORKSHOPS, SEMINARS AND MEETINGS-------------------194

PART-I
SEISMIC MICROZONATION OF COXS BAZARMUNICIPAL AREA

Prepared By
Afifa Imtiaz
Mehedi Ahmed Ansary

BANGLADESH NETWORK OFFICE FOR URBAN SAFETY(BNUS), BUET, DHAKA

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ABSTRACTThe purpose of this study is to develop geotechnical microzonation maps using Geographical
Information Systems (GIS). Coxs Bazar Municipal Area, located in the Southeastern regionof Bangladesh, beside the Bay of Bengal, has been chosen as the study area. The model
inputs include site amplification, liquefaction potential study and slope stability analyses. It is
now well known, and widely accepted amongst the earthquake engineering community, thatthe effects of surface geology on seismic motion exist and can be large. Nearly all recent
destructive earthquakes have brought additional evidence of the dramatic importance of site
effects. Accounting for such "site effects" in seismic regulations, land use planning or designof critical facilities thus has become one goal of earthquake hazard reduction programs.
Coxs Bazar area, having been a great tourist resort, has experienced a rapid urbanization in
the last few decades including various establishments, construction of significant number ofbuildings and other structures in an unregulated manner and without seismic design
considerations. Landslide and related casualties have also become very common in the hilly
areas of the locality. In order to assess seismic vulnerability based on ground susceptibility
and adopt mitigation strategies for urban areas, seismic microzonation is considered to be thefirst step. This study deals with the microzonation of the Coxs Bazar Municipal Area using
geographic information system (GIS) where reflection of ground shaking and the site
attributes of soil amplification, liquefaction and landslide are the salient features. The
probable earthquake hazard and expected ground motion for this area were assessed using
probabilistic approach. The liquefaction potential was estimated from Standard Penetration
Test (SPT) following the methods suggested by Seed and Idriss combined with Japanese
Code of Bridge Design. SHAKE analysis was performed for estimation of 1D site
amplification. Slope stability analyses were performed for samples from the hilly regions of
the area using the program XSTABL. The results obtained for site amplification, liquefaction
and landslide potential were exported in GIS environment and presented as microzonation
maps.
The findings of the study show that the rock level Peak Ground Acceleration (PGA) of thearea is 0.18g for a 7.5 magnitude earthquake having a return period of 200 years. The surface
PGA could be as high as 0.41g for an average 2.3 times amplification factor if extreme ormost severe condition is considered. For this, ground shaking amplified by 2, 2.5 and 3 times

1March 2010

can affect 47%, 42% and 11% of the municipal area respectively. 87% of the study area ishighly susceptible to liquefaction and approximately 8% of the municipality consists of hilly
region whose 97% is very unsafe regarding natural slope stability. On the other hand, surface
PGA will be 0.31g for an average amplification factor of 1.7 if a refined hazard condition isassumed based on average horizontal spectral acceleration technique. 89% area will beaffected by 1.7 times amplification of ground shaking and 58% area will be prone to highliquefaction potential. 96% of the hilly region will become vulnerable if high landslide
associates with only 1.7 times amplification of ground shaking.
1.1 Background
Bangladesh runs a high risk of experiencing earthquakes due to her geological and tectonic
structures. The northern region of Bangladesh lies above the seam of the Indian and Eurasian
tectonic plates and the eastern part is above the joint of the Burmese and Indian plates. The
Indian plate is edging north-east while the Burmese plate is moving north-west. The
countrys position adjacent to the very active Himalayan front and ongoing deformation in
nearby parts of south-east Asia expose it to strong shaking. In the recent past, a good numberof tremors of moderate to severe intensity had already taken place in and around Bangladesh.
Coxs Bazar, located in the southeastern part of Bangladesh, is a strategically andeconomically important area of the country. The district is exposed to the most devastating
natural disasters of the country. In the seismic zoning map of Bangladesh, provided in BNBC
(Bangladesh National Building Code 1993), Coxs Bazar has been shown under Zone II withdesign Peak Ground Acceleration (PGA) value of 0.15g (Z=0.15). This level of acceleration
may be considered as more or less equivalent to a seismic intensity between VII and VIII.
Historical information reveals that earthquakes of magnitude between 6 and 7 have occurred
around the area in the past. Thus Coxs Bazar and the nearby area are considered to fall in theHigh Risk Zone for earthquakes. The frequent earthquakes in and around the country,
particularly Chittagong and Coxs Bazar regions, also point toward the potential of suchintensity earthquakes, even much higher than that projected. Therefore, it is essential toassess the earthquake hazard and related secondary effects for the region in order to aid theearthquake risk mitigation efforts.
Cox's Bazar, having been a great tourist resort, a rapid urbanization has occurred in the lastfew decades including various establishments, construction of significant number of2

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buildings and other structures in an unregulated manner and without seismic design
considerations. The consequences of moderate to strong earthquake event can be catastrophic
if such a densely populated urban area is affected and may have very severe long-term
consequences for the entire country.
One of the major concerns during an earthquake is the presence of vulnerable soil near the
ground surface. In order to assess seismic vulnerability based on ground susceptibility,
seismic microzonation is considered to be the first step towards a seismic risk analysis andmitigation strategy for urban areas. Therefore this study deals with the microzonation of theCoxs Bazar Municipal Area based on liquefaction potential, site amplification and land slide
potential. Figure 1.1 shows the location map of Coxs Bazar Municipal area.
Liquefaction phenomena can affect buildings, bridges, buried pipelines, lifelines and otherconstructed facilities in many different ways. Coxs Bazar is mostly a hilly region consistingof alluvial flood plain and sandy sea shore area. The area bottom of the hill can liquefy if theintensity of shaking is high, which may cause land slide in the hilly region. On the other handfloodplains and sea shore areas consisting of fine sand and silt deposit with shallow watertable in most of the places may liquefy during a strong earthquake.
Site Amplification is an important basis of microzonation. The basic intention of
amplification assessment is to estimate the effect of local site conditions through the site
response analysis. This factor is highly dependent on the local soil conditions and on the
expected earthquakes. Local soil effects can amplify the ground motion and thus lead tointensity greater than the projected ones in certain areas causing more damage. In theurbanization process it has become a common practice to fill up many low lying lands orshallow water bodies in the town area for construction. The filled soils in many cases are notproperly compacted or consolidated. Furthermore, the low lying lands may also possess soft
soils. These soft soil sites may cause amplification and modification of ground motion,
producing larger seismic forces in buildings. Coxs Bazar area is also characterized by asignificant amount of sediment and landfill, which may greatly amplify seismic waves and isanother issue of concern for studying the site effects.
Landslide has become very common in the hilly areas of southeastern Bangladesh, especiallyin Bandarban, Rangamati, Khagrachhari and Cox's Bazar. Illegal hill-cutting due to rampant3

March 2010

building has left some 70,000 (IRIN, 2008) people at risk of landslides in 18 sub-districts of
the hill districts, as well as the city of Chittagong, warned specialists. Every year especially inthe rainy season landslides take place in both natural and man-induced slopes. Considerable
number of buildings, roads and other infrastructures are damaged and valuable lives are lostin these incidents. The loss of lives and properties due to landslide events in Coxs Bazar isalso very significant. Now time has come to find out the cause of such events in the area andto take necessary preventions to avoid repeated casualties. Therefore assessment of landslide
potential of Coxs Bazar has become very essential. Indiscriminate Hill cutting is one of the
major causes of landslide. Landslide may be caused by earthquake in steep hill and loose landof steep periphery. Gentle angle or slope is mostly absent in the hills of Coxs Bazar due tohuman activities. Rock strata in this area are mostly found as soft or brittle sedimentary rocks
which may easily be broken or slide. Since Coxs Bazar is on the threat of probable
earthquake events, the hill-tops loosened by any means can cause massive destruction if amoderate to major tremor takes place.

Seismic hazard due to local site effects such as soil amplification, liquefaction, and landslide
can be estimated by combining the available soil parameter data with the current hazard
status of the region. Moreover, for accomplishing comprehensive regional hazard assessment,
geographic information system (GIS) provides a perfect environment. Therefore this study
deals with the microzonation of the Coxs Bazar Municipal Area using geographic
information system where reflection of ground shaking and the site attributes of soil
amplification, liquefaction and landslide are the salient features. Microzonation maps can beused for planning locations and construction of future facilities. The GIS-based analysis isuseful to engineers, planners, emergency personnel, government officials, and anyone else
who may be concerned with the potential consequences of seismic activity in a given region.
Microzonation maps presented on a GIS platform provides the results of a regional seismic
hazard and risk analysis that serve as an effective means of transferring information from thescientific community to the professional community of decision makers involved in hazard
and risk mitigation. Hence these zonation maps will add value in planning of the coastal town
Coxs Bazar by helping in finalizing design of many important structures and saving
construction time and cost.

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1.2 Objectives of the Study
The goal of the study is to develop maps showing local site effects such as the liquefaction
potential, site amplification and landslide potential for Coxs Bazar Municipal area in
Bangladesh. The following are the specific objectives of the research:1.

To compile a subsoil investigation database for different locations of Coxs Bazar
Municipal area

2.

To determine the Site Amplification of the Area based on 1D-SHAKE analysis

3.

To determine the Liquefaction Potential of the Area based on Geology, standard
penetration test (SPT) and laboratory test results.

4.

To demarcate the regions susceptible to Landslides due to natural slope instability

5.

To determine the combined effects of the aforementioned hazards to ground shaking.

6.

To present the results of the study in GIS based Maps.

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1.3 Methodology of the Study
Bore-hole soil data, geophysical measurements, historical data, reports and published papers
have been used to identify the vulnerable locations and estimate necessary soil parameters.
Standard analytical methods have been used to develop site amplification scenarios,liquefaction potential and landslide potential of Cox's Bazar district. Figure 1.2 shows themethodology adopted for this study.

Figure 1.2: Methodology of the study

2.1 Overview of the Study Area
Cox's Bazar is a town; a fishing port and a district headquarter in Bangladesh. It is known for
its wide sandy beach which is claimed to be the longest natural sandy sea beach in the world.
It is located along the Bay of Bengal in Southeastern Bangladesh and 150 km south of
Chittagong. Cox's Bazar derives its name from Captain Cox, an officer serving in British
India. Cox's Bazar thana was first established in 1854 and the municipality was constituted in
107March 2010

1869 (Banglapedia, 2004). In 1959 the municipality was turned into a town committee. The
town committee was replaced by municipality in 1972 and it was elevated to B grade in 1989.
Cox's Bazar municipality covers an area of 6.85 sq km with 27 mahallas and 9 wards, islocated at 21.58333°N 92.01667°E and bounded by Bakkhali River on the North and East,
Bay of Bengal in the West, and Jhilwanja Union in the South. Population of the area is 51918(BBS, 2001). As one of the most beautiful and famous tourist spots of Bangladesh, the major
source of economy of Cox's Bazar is tourism. Millions of foreigners and Bangladeshi natives
visit this coastal town every year. Therefore, a number of hotels, guest houses, and motels
have been built in the town and coastal region.
2.2.1 Geomorphology of Coxs Bazar District
The district of Cox's Bazar is bounded on the west and south by the Bay of Bengal, on theeast by the hill ranges of elevation around 100-200 m. Basin of Matamuhuri River andBakkhali river form the morphological pattern on the North of the district. The landmass ofthe district of Cox's Bazar includes two distinct geological settings namely Tertiary folded
belt and coastal deposits. The tertiary folded belt extends north-south as part of the IndoBurmese mobile belt, which is characterized by long narrow folds (Alam et al., 1990). Floodplain and coastal deposit of Holocene age overlies late Tertiary formations at places
presenting the surface form. The present day morphology of the area are believed to be
influenced by the Holocene sea level rise, tidal and fluvial discharges and very special type ofphysical set up of the plain around Tertiary Hills (Huq and Ahmed, 1997).
Alam et al. (1999) present the morphology of Cox's Bazar coastal plain as shown in Figure
2.2. The schematic cross-section shows that the plain is elevated landward and graduallyslope toward the sea. The elevation of the marginal part of the plain is of the order of 2 to 3 m
above mean sea level. The characteristics of different landforms are shown in Table 2.1.
Table shows that sediment of the plain varies from very fine silt to medium sand with finerparticles at the flood plain and largest grain size for tidal creeks.

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Table 2.1: Landform Characteristics of the Cox's Bazar Coastal Plain(after Alam et al., 1999)

Figure 2.1: Map showing 9 wards in Coxs Bazar Municpal Area

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Figure 2.2: Morphology of Coxs Bazar Sadar (Alam et al., 1999)

2.2.2 Geology of Coxs Bazar Municipal Area
Coxs Bazar town is located at the Middle-West part of the district bounded by the BakkhaliRiver on the North and North-East. The area lies within the Eastern flank of Inani Anticline,
trending towards NNW-SSW, whose Western Flank is eroded. The existing Eastern Flank of
the anticline is also in the process of continuous erosion. Figure 2.3 shows the Surface
Geology of Cox's Bazar Municipal area according to the Geological Map of Bangladesh(after Alam et al., 1990). The Western Figure reveals that the area around the Cox's Bazar
municipality predominantly composed of Valley Alluvium and Colluvium and Dihing
Formation of Pliocene-Pleistocene age. Rocks of the Pliestocene, Pliocene and Neogene ages
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are also exposed in the area. The exposed rock units are mostly composed of sandstone andclaystone. Six Lithostratigraphic units have been observed from the Geological Map ofBangladesh.
To the West of the Municipal Boundary, the strand of Coastal Deposit, Beach and Dune
Sand, lies extending towards south. This is a narrow zone of Coastal Deposit along thewestern edge of the tectonically active Fold Belt. Beach and Dune Sand are characterized aslight to whitish grey sand being medium to fine, well sorted, subrounded; containing
concretion, shell fragments, heavy minerals, and rare clasts. It also includes small mud-flat
deposits. This formation uncomfortably overlies Late Tertiary formations.
To the East of Beach and Sandstone, there lies another narrow zone of Boka Bil Formationof Neogene age. It is greenish to bluish-grey and yellowish grey shale, siltstone andsandstone. Sandstone is very fine to medium grained; flaser bedding and starved ripple
marks are found to be very common. In the upper and lower parts of the formation, shalecommonly dominates and is interbedded with siltstone and sandstone; middle part isdominated by massive, hard, locally calcerous, conglomeratic sandstone. Middle and lower
parts contain calcareous lenses and concretions. It locally contains some fossiliferous beds aswell.
A slight narrow zone Tipam Sandstone of Neogene age forms the Eastern side of Boka Bilzone. The layer is light yellow to yellowish grey, grey, brownish-grey, and orange, fine tomedium-grained pebby sandstone, sub angular to sub rounded; siltstone, and shale; massive
to thin-bedded, containing intraformational clasts and ferruginous concretions; soft andfriable. It locally contains silicified wood and lignite. Upper and lower parts of the formation
are predominantly sandstone; middle part is predominantly shale, silty shale and siltstone.
The Neogene rock units represent sediments derived from the Himalayan and Shilong Plateau
of India and derived from the Arakan-Yoma Mountains of Myanmar. These formations areprobably time transgressive to the south and to the west; their lithology varies vertically andhorizontally with distance from the source.
Along the East of Tipam Sandstone zone, another formation of Bedrock from Tipam Group
that is Girujan Clay of Pleistocene and Neogene age lies. This zone is composed of Grey to
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greenish grey, red mottled, silty shale, shale and claystone and interbedded with subordinate
thin-bedded siltstone and crossbedded sandstone. This formation contains calcareous
claystone nodules, ferruginous sandy concretions, clay galls, quartzite pebbles, thin lignite
beds, silicified wood and leaf impressions.
The North Eastern boundary of the town consists of Alluvial Deposits of Valley Alluvium
and Colluvium. This formation consists of medium to dark-grey or light-brown silt, clayey
silt, and fine to medium sand; locally contains coarse debris derived from local bedrock andorganic matter. Colluvium is flushed into narrow valleys and reworked by alluvial processes.
This unit is susceptoble to mass-movement processes such as landslides, earth slump andmud flows.
The south eastern part of the town has basically Dihing Formation Bedrock which ischaracterized by yellow to yellowish-grey, massive, fine to medium grained poorly
consolidated sandstone and clayey sandstone. Mottled clay and pebble beds occur locally. In
Fold Belt, pebbles are quartzite. It is highly weathered and contains silicified wood;
ferruginous crust is present locally. Dupi Tila Formation of Pleistocene and Pilocene age lies
to the south of Dihing Formation which might have a slight influence in the surface geologyof the town. Dupi Tila is characterized as yellow to ochre, pink, light-brown, light-grey tograyish-white or bluish grey sandstone, siltstone and conglomerate. It is massive to thinbedded, containing quartz and shale pebbles, clay galls and pellets, silicified wood and lignite
fragments. Upper part of the formation is dominated by fine to medium grained sandstone,
subordinate thin beds of siltstone and claystone, intraformational siltstone breccias at top.
Lower part is dominated by sandstone and the zone is locally crossbeded.

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Figure 2.3: Geology of Cox's Bazar Municipal (Alam et al, 1990)

Figure 2.3: Geology of Cox's Bazar Municipal (Alam et al, 1990)

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in Bangladesh
2.3 Status
StatusofofEarthquakes
Earthquakes
in Bangladesh

Bangladesh is a country located in south Asia. Figure 2.4 shows the seismicity of southern
Asia according to British Geological Survey. It shows that Bangladesh is covered by many
points indicating earthquake events. It is obvious that Bangladesh is surrounded by theregions of high seismicity, which include the Himalayan Arc and Shillong Platue in the north,the Burmese Arc, Arakan Yoma anticlinorium in the east and complex Naga-Disang-Jaflong
thrust zones in the northeast (Rahman 2008, Sarker et al. 2004). It is also the site of the Dauki
Fault system along with numerous subsurface active faults and a flexure zone called Hinge
Zone. These weak regions are believed to provide the necessary zones for movements within
the basin area.
Earthquake catalogue for Bangladesh and surrounding area (Sharfuddin, 2001) shows that1200 earthquakes with magnitude 4.0 have occurred between 1865 to 1999. During the last
150 years, seven major earthquakes with magnitude 7.0 have affected Bangladesh. Two ofthem had their epicentres within Bangladesh and caused considerable damage locally. The
1897 Great Indian earthquake (M=8.7) in Shillong, considered to be one of the strongest
earthquakes of the world, had its epicentre only 230 km away from Dhaka and caused
extensive damage to brick masonry structures in Bangladesh including Dhaka. Figure 2.5
reveals earthquakes of different magnitudes in and around Bangladesh. It shows that theearthquakes of the greater magnitude occurred in the northern part of the country. From theCoxs Bazar area also fall under moderate
figure it can be seen that Chittagong and Cox�searthquake zone having magnitude of 6 to 7 in Richter scale.

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Bangladesh

Figure 2.4: Seismicity of Southern Asia (The Tsunami Page, 2005)

Figure 2.5: Earthquake in and around Bangladesh (1865-1995)(after Ansary, 2009)18
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2.4 Historical Earthquakes in Bangladesh
Accurate historical information on earthquakes is very important in evaluating the seismicityof Bangladesh. Information on earthquakes in and around Bangladesh is available for the last
250 years. Appendix A provides a list of the historic earthquakes recorded in and around
Bangladesh according to Scribd, 2008. The earthquake record suggests that since 1900 morethan 100 moderate to large earthquakes occurred in Bangladesh, out of which more than 65
events occurred after 1960. This brings to light an increased frequency of earthquakes in thelast 30 years. This increase in earthquake activity is an indication of fresh tectonic activity or
propagation of fractures from the adjacent seismic zones. The Meteorological Department of
Bangladesh established a seismic observatory at Chittagong in 1954 which is the only
observatory in the country.
The major earthquakes that have affected Bangladesh since the middle of the last century arepresented in Table 2.2.
Table 2.2: Great historical earthquakes in and around Bangladesh
Name

Epicentre

10-01-1869

Cachar Earthquake

Jantia Hill, Assam

7.5

14-07-1885

Bengal Earthquake

Sirajgonj, Bangladesh

7.0

12-06-1897

Great Indian Earthquake

Shillong Plateau

8.7*

18-07-1918

Srimangal Earthquake

Srimangal, Sylhet

7.6

02-07-1930

Dhubri Earthquake

Dhubri, Assam

7.1

15-01-1934

Bihar-Nepal Earthquake

Bihar, India

8.3

Date

*

Magnitude (M)Recently modified as 8.1(M) (Ambraseys, 2000)

2.5 Major Seismic Sources
The seismic hazard is typically determined using a combination of seismological,
morphological, geological and geotechnical investigations, combined with the history ofearthquake in the region. Figure 2.6 shows the tectonic features of Bangladesh and adjoining
areas. Figure 2.7 shows the distribution of faults and lineaments in Bangladesh.
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Bolt (1987) analyzed different seismic sources in and around Bangladesh and arrived atconclusions related to maximum likely earthquake magnitude (Bolt, 1987). Bolt identified thefollowing four major sources:(i)

Assam fault zone(ii)

Tripura fault zone(iii)

Sylhet fault zone(iv)

Bogra fault zone

Recently, Whitneyhashasadded
two twomajor
possiblesourcesourcezones, namely
Shahzibazar
Fault andRecently,
Whitney(2004)(2004)
added
major
possiblezones, namely
Shahzibazar

Fault
Figure2.8 shows lineaments
seismotectonic
lineaments
faults capableofTanor andFault.Tanor
FigureFault.
2.8 showsseismotectonic
and faults
capable andof producing
damaging
producingearthquakes
in Bangladesh.
The magnitudes
earthquake
earthquakesdamaging
in Bangladesh.
The magnitudesof earthquake
suggested by ofBolt
is shown insuggested
Table 2.3
byis shown in
Table 2.3
are the maximum
magnitude
generatedthese blocks
asin these blocks
as recordedin thein historicalseismic
are Bolt
the maximum
magnitude
generatedrecordedthehistoricalhistoricalseismic
catalogue.
historicalseismic catalogue
of ofthe(starting
regioncatalogue.inThe
seismic
catalogueof the The
regioncovers approximately
250 years
coversapproximatelyof (starting1762)
earthquake
example,the Assam1762) earthquake
data.250
For years
example,the Assam
and Tripura
fault data.
zonesFor
containsignificant
faultsand Tripura fault zones contain significant faults capable of producing magnitude 8.6 and 8.0
capable of producing magnitude 8.6 and 8.0 earthquakes respectively in future. Similarly maximum

earthquakes respectively in future. Similarly maximum magnitude of 7.5 in Sub-Dauki fault
magnitude of 7.5 in Sub Dauki fault zone and Bogra fault zones are not unlikely events.

zone and Bogra fault zones are not unlikely events.

Table 2.3: Significant seismic sources and maximum likely earthquake magnitude in
Bangladesh (after Bolt, 1987)
Location
Assam fault zone
Tripura fault zone

8.0
7.0

Sylhet fault zone

7.3

Bogra fault zone

7.0

After a thorough review of available data, Ali and Choudhury (1992) recommended
After a thorough review of available data, Ali and Choudhury (1992) recommended magnitudes ofmagnitudes of Operational Basis Earthquakes and Maximum Credible Earthquakes as shown
OperationalinTable 2.4.Basis Earthquakes and Maximum Credible Earthquakes as shown in Table 2.4.
Table 2.4: Operational basis earthquake, maximum credible Earthquake and depth of focus ofearthquakes for different seismic sources (after Ali and Chowdhury, 1992)
Location
Operational basis
Maximum
Depth of focus (km)earthquakes (Richter)
Credibleearthquakes

Assam fault zone

8.0

8.7

0 70

Tripura fault zone

7.0

8.0

0 70

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Sylhet fault zone

7.3

7.5

0 70

Bogra fault zone

7.0

7.5

0 70

Sylhet fault zone

7.3

7.5

0 70

Bogra fault zone

7.0

7.5

0 70

Figure 2.6: Generalized tectonic map of Bangladesh and adjoining areas

Figure 2.6: Generalized tectonic map of Bangladesh and adjoining areas

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Figure 2.7: Distribution of faults and lineaments in Bangladesh (Banglapedia, 2004)

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2.6 Historical Earthquakes in and around Coxs Bazar
In recent years, earthquakes have occurred quite frequently in Bangladesh and have caused
alarm especially in Chittagong and Moheshkhali causing structural damage and casualties.
2.6.1 Chittagong Earthquake of 1762
Historical documents mention the occurrence of a large earthquake on April 2, 1762 (Rastogi
et al., 2006) near Chittagong in the south-east which caused sea flooding, river waves inland,
land mass changes etc. It is among the earliest known large earthquakes in South Asia. The
earthquake, a major one (possibly M>7.0), was centred 40 km SE of Chittagong and 257 km
SE of Dhaka, 61 km north of Cox's Bazar district. Chittagong suffered very severely; great
explosion heard at first; earth opened in many places; quantities of water gushed out, greatchasms remained unclosed and filled with water. Water spouted out like a fountain together
with fine sand or mud, evidence of liquefaction. The great earthquake of April 2 raised thecoast of some islands by several metres and also caused a permanent submergence of 155.40
sq km near Chittagong. At Dollazari houses fell. Near Luckipore, a circuit of land, about 15
miles in circumference, was swallowed up, and all the inhabitants and cattle perished. The
earthquake also agitated the rivers and lakes of the country causing deaths inside the country.
2.6.2 Chittagong Earthquake of 1997
In November 21, 1997 another damaging earthquakes of body-wave magnitude 6.0 haveoccurred in Bangladesh (Sharfuddin, 2001). During this earthquake, 23 people were killed
after collapse of an under-construction building in Chittagong. In Chittagong many low to
middle rise buildings have suffered minor cracks although major damage has not been
observed. The epicentral area (22.225N, 92.743E) is close to Ruma in Bandarban district ofChittagong Hill Tracts region. Many houses were damaged and old trees were uprooted in theepicentral region. Partial collapse of a long earthen dam (Prantik lake) has been observed.
2.6.3 Moheskhali Earthquake of 1999

On July 22, 1999, at 4:42 pm (local time), an intense earthquake shook the island ofMoheskhali causing damage to several houses and some buildings, killing 6 people andinjuring 200 people. The main damage has been reported to be in Shaplapur and Huanok
Unions. Dineshpur and Kaidabad under Shaplapur Union were reported to have heavy
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damages. Cracking and spalling in reinforced concrete columns at the beam-column joint
occurred in a cyclone shelter at Dineshpur. Several rural houses with mud walls and thatchedor tin roof construction were severely damaged. At Kaidabad EU cyclone shelter was also
badly damaged. Severe cracking was formed in many mudwall houses at Bara Maheshkhali
and Huanok Union. Some landslides were also observed which could have been triggered by
the earthquake.

Figure 2.9: Isoseismal of Maheshkhali Earthquake of 1999 (Ansary et al., 1999)

The hypocentre of the earthquake was initially estimated to be at 21.47oN, 91.90oE (focal
depth = 10 km, origin time 16:42:12) (Sharfuddin, 2001). The focal depth of this earthquake
was quite shallow. The location of the hypocenter was later corrected as at 21.54oN, 91.88oE.
The magnitude of the main shock was 5.1 on bodywave magnitude scale. Three more
aftershocks of smaller intensity occurred in the same island on the following night. Figure 2.9
shows the seismic intensity map based on the observed damage and questionnaire survey(Ansary et al., 2001).

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2.6.4 Database of Earthquakes in and around Coxs Bazar
Historical data (1923-2008) for seismic activity affecting Coxs Bazar and surrounding area
show that the area has undergone through frequent earthquakes of magnitude ranging from 5
to 6 in Richter scale. Epicenters of these earthquakes (Appendix B) with reference to the 250
km radius of the municipality reveal that the earthquake with the highest magnitude (6.5 in
Richter scale) occurred in this region in 1955. Again, considering 450 km radius around thestudy area, it is observed that the highest magnitude earthquakes experienced occurred in
1664, 1858, 1912 with magnitudes 7.8, 7.66, 7.9 consecutively (Ansary, 2009). Figure 2.10
shows the plot of frequency of the earthquakes occurring from 1919 to 2008 over the decades.
The figure depicts that earthquakes having magnitude higher than 5.0 are recurring in almost
every decade in this region. Again the frequency of earthquakes with magnitude varied from
4.0 to 5.0 has increased markedly over the last four decades. These historical records andobservations indicate the probable occurrence of moderate to high intensity earthquakes in
the upcoming years in and around Cox's Bazar.
2.7 Seismic Zoning Maps
In the Bangladesh National Building Code (BNBC) published in 1993, a new seismic zoning
map for Bangladesh has been presented. The pattern of ground surface acceleration contours
having 200 year return period forms the basis of this seismic zoning map. The 1993 BNBC
zoning map is shown in Figure 2.11. In this zoning map the country has been divided into
three generalized seismic zones: zone-I, zone-II and zone-III.
Zone-I comprising the Northern and Eastern regions of Bangladesh with the presence of the
Dauki Fault system of Eastern Sylhet and the deep seated Sylhet Fault, and proximity to thehighly disturbed southeastern Assam region with the Jaflong thrust, Naga thrust and Disang
thrust, is a zone of high seismic risk with a basic seismic zoning co-efficient of 0.25 (Rahman
2008, Sarker et al. 2004). Northern Bangladesh comprising greater Rangpur and Dinajpur
districts is also a region of high seismicity because of the presence of the Jamuna Fault andthe proximity to the active east-west running fault and the Main Boundary Fault to the northin India (Rahman 2008, Sarker et al. 2004). The Chittagong-Tripura Folded Belt experiences
frequent earthquakes, as just to its east is the Burmese Arc where a large number of shallow
depth earthquakes originate.

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Figure 2.10: Earthquake Occurrences in and around Coxs Bazar municipal area (19192008) (after Ansary, 2009)
Zone-II comprising the central part of Bangladesh represents the regions of recent uplifted
Pleistocene blocks of the Barind and Madhupur Tracts, and the western extension of thefolded belt. The zone extends to the south covering Chittagong and Coxs Bazar. Seismic
zoning coefficient for Zone II is 0.15.

The Zone-III comprising the southwestern part of Bangladesh is seismically quiet, with anestimated basic seismic zoning co-efficient of 0.075.

Bangladesh National Building Code (BNBC, 1993) placed Coxs Bazar in Seismic zone 2.
The zoning map has recently been updated (Sharfuddin, 2001) and shown as Figure 2.12. The
zoning in this updated map was based on consistent ground motion criterion such as equalpeak ground acceleration levels. According to this map, Coxs Bazar falls in Zone 3. Basedon the philosophy behind this seismic zoning and experience from recent earthquakes, it canreasonably be assumed that a major earthquake event in Coxs Bazar and surrounding region
is liable to higher damage than that assumed in the existing zoning map (BNBC 1993).
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Figure2.11:
2.11:Seismic
SeismicZoning
ZoningMap
MapofofBanglades
Bangladesh
Figureh(BNBC,1993)
1993)(BNBC,

258585

March 2010

Figure 2.12: Updated Seismic Zoning Map of Bangladesh(Ansary, 2009)

2.8 Seismic Microzonation
Seismic microzonation can be defined as the subdivision of a region into zones that haverelatively similar exposure to various earthquake related effects. It is the mapping of seismic
hazard at local scales to incorporate the effects of local soil conditions. The earthquake

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damages are controlled basically by three interacting factor groups; earthquake source andpath characteristics, local geological and geotechnical site conditions, structural design andconstruction features. Seismic microzonation can be considered as the assessment of the firsttwo groups of factors. In general terms, it is the process for estimating the response of soil
layers under earthquake excitations and thus the variation of earthquake characteristics on the
ground surface. Seismic microzonation is the initial phase of earthquake risk mitigation andrequires multidisciplinary approach with major contributions from geology, seismology,
geotechnical and structural engineering. The final output contains recommendations suitable
for application by local administrators, urban planners and engineers.
The national seismic zoning maps are generally prepared in small scales such as 1:1,000,000
or less neglecting numerous source and site factors that are important in assessing groundmotion characteristics. Seismic microzonation maps are prepared based on larger scales for aparticular region taking into consideration both earthquake source and regional geologicaland geotechnical site conditions in order to be used for urban and landuse planning. A
Seismic microzonation study consists of four stages: (1) estimation of the regional seismic
hazard that is asessment of the expected input motion, (2) determination of the local
geological and geotechnical site conditions (3) assessment of the probable ground response
and ground motion parameters on the ground surface (4) finally, preparation of
microzonation maps.
2.8.1 Function of GIS in Microzonation
The regional earthquake hazard analysis requires a map of the region that identifies thepotential seismic sources. This procedure typically requires several geologic and geographic
maps of the region. The bedrock motion in the region resulting from the seismic event mustfirst be determined. This is often done by applying one of the attenuation functions within the
GIS or by linking the function as an external executable program. The GIS-based procedure
for estimating regional bedrock motion is straight-forward. Quantifying and integrating theseismic hazard due to local site effects (soil amplification, liquefaction, and landslide) is themain areas of development presented in this dissertation. The procedure involves developing
models for each of the effects, assembling the necessary geologic and geographic maps anddatabases, applying the models either within the GIS or as linked external programs and thenoverlaying and combining the resulting hazard maps.

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The resultsfrom the analysis
analysis are microzonation
microzonation maps
study area. These
These maps
The
results obtained
obtained frommaps forfor thethe study
typically requirea detailed
layoutfor thea quantificationof the regional
hazardandtypicallyrequirea detailed
layoutforregion,
the region,a quantificationof theseismic
regional
seismic
accountsandof susceptibility
to the expected
The spatial
databaseof a GIS
hazardaccounts of due
susceptibility
due tohazards.
the expectedhazards.
Thestructure
spatial databaseenvironment
idealenvironment
for this procedure.
this
study
MapInfoInProfessional
7.0 software
has been
structureof aisGIS
is idealInfor
this
procedure.
this study “MapInfo
Professional
used softwarefor developing
maps.
7.0”
has beenused for developing maps.

2.9 Attenuation Law of Peak Ground Acceleration
The quantitative assessment of seismic hazard at any particular site within a region requires
an attenuation law for the Peak Ground Acceleration (PGA). This describes the transfer ofground motions from the source to a particular site as a function of magnitude, distance andsoil conditions. The maximum ground motion to be expected in the site constitutes a crucial
problem in earthquake engineering. For Bangladesh, as in many other parts of the world, no
PGA attenuation law has been developed, due mainly to the shortage of strong motion data.
However, in order to assess the seismic hazard in this region, an attenuation law needs to be
adopted from the literature. PGA attenuation relationships, predicting strong ground motionsin terms of magnitudes, distance, site geology, and in some cases other factors, using various
models and data sets are established for different parts of the world. Reviews of these laws
are presented in Campbell (1997) and Joyner and Boore (1988). Some of the publishedattenuation functions are presented in Table 2.5. Attenuation relationships of ground motions
are of the form:
log(y) = b1 + b2 (Ms) b3 log (r) b4 (r)) + P(2.1)

where y is the ground motion parameter in consideration, M is earthquake magnitude, b 1,2,3,4
are constants determined for the ground motion parameter,is the standard deviation

representing the scatter of data in the attenuation relationship and P is a parameter whichtakes the value of 0 (zero) when the predicted value represents the mean and P equals one
when the predicted value represents the mean plus one standard deviation. r is a distanceparameter, usually of the form r = (d2 + h2).

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Table 2.5: Published attenuation function (after Islam, 2005)
AuthorLaw

Duggal (1989)

y=227x100.308M(d+30) 1.2

McGuire (1978)

y=0.0306e0.89Mr 1.17e 0.2S ; Where S=0 for rock and S=1 for alluvium

Katayama (1974)

logy=2.308-1 637log(r+30)+0.411M

Sadigh, et al. (1986)

ln y = 1.406 + 1.1 M  2.051 (R + 1.353 e0.406M ); Where M > 6.5

Joyner and Boore (1988)

log y = 0.43 + 0.23 (M  6)  log (r2 + h2) 1/2  0.0027(r2 + h2 )1/2; for rockAmbraseys (1995)

log y=-l.43+0.245Ms-0.001r-0.786logr; here, r=(d2+2.72)1/2
ln y = 0.2424 + 0.527(M 6)  0.778 ln r  0.371 ln Vs / 1.396

Boore et al. (1997)

where, r = ( rb 2 + 5.572 ) 1/2 , rb = epicentral distance in km,
Vs = average shear wave velocity of surface 30 m

Joynner and Boore(1981)

y = 0.0955 e(.573M) d( 1)* e( 0.00587D), d= (r2+h2)0.5, for rock

Where, y=PGA; M= surface magnitude; d=epicentral distance; r=hypocentral distance; h=focal depth

2.10 Seismic Hazard Assessment
The first step in microzonation is the estimation of seismic hazard. This involves theassessment of expected ground motion using the deterministic or probabilistic seismic hazard
analysis. Numerous methods for earthquake hazard assessment in a given site are available today.
Lomnitz and Epstein (1966) employed the Poisson process for the occurrence of large earthquakes

which is still used. Cornell (1968) and Esteva (1968) derived the general basis for the mostcomplete analysis of the whole seismic hazard problem with the inclusion of the propagation
mechanism of the ground motion. Shah and Vagliente (1972) used the Markov model ofearthquake prediction in seismic hazard analysis. A methodology for seismic hazard
estimation based on historical earthquake occurrences is presented in detail in Tomatsu andKatayama (1988) and Molas and Yamazaki (1994). In Japan, the seismic risk method
proposed by Kawasumi (1951) is still popular while in the United States, the basic method
proposed by Cornell (1968) is often used

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2.10.1 Deterministic Seismic Hazard Analysis
Krinitzsky (2005) highlights that a Deterministic Seismic Hazard Analysis (DSHA) uses
geology and seismic history to identify earthquake sources and to interpret the strongest
earthquake each source is capable of producing regardless of time. Those are the Maximum
Credible Earthquakes (MCEs), the largest earthquake that appears possible along arecognized fault under the presently known or presumed tectonic activity which will cause
the most severe consequences to the site.
The methodology followed for Deterministic Seismic Hazard Analysis is described asfollowed:
1. Source characterization, that includes identification and characterization of allearthquake sources which may cause significant ground motion in the study area.
Here historic data of the earthquakes as well as the availability of the source ofearthquake such as faults are used to determine the potential of the earthquake
occurrence.
2. Selection of the shortest distance between the source and site of interest.
3. Selection of controlling earthquake, that is, the earthquake that is expected to produce
the strongest level of shaking. Controlling earthquake has been evaluated based on
historic data and assumed subsurface fault rupture length.
4. Defining the hazard at the site formally in terms of the ground motion produced at thesite by the controlling earthquakes.

2.10.2 Probabilistic Seismic Hazard Analysis
PSHA is the most commonly used approach to evaluate the seismic design load for theimportant engineering projects. PSHA method was initially developed by Cornell (1968) andits computer form was developed by McGuire (1978). Site ground motions are estimated forselected values of the probability of ground motion exceedance in a design period of thestructures or for selected values of annual frequency or return period for ground motion
exceedance. The probabilistic approach offers a rational framework for risk management by
taking account of the frequency or probability of exceedance of the ground motion against
which a structure or facility is designed. The occurrence of earthquakes in a seismic source isassumed as the Poisson distribution. The probability distribution is defined in terms of the30

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annual rate of exceeding the ground motion level z at the site under consideration, due to allannualannual rate
rate ofof exceedingexceeding thethe groundground motion
motion level
level zz at
at thethe sitesite under
under consideration,
consideration, due
due toto allallpossible pairs (M, R) of the magnitude and epicentral distance of the earthquake event
possiblepossible pairs
pairs (M,(M, R)
R) ofof thethe magnitude
magnitude andand epicentral
epicentral distancedistance ofof thethe earthquake
earthquake event
event
expected around the site, considering its random nature. This procedure can be described in
expected
expected aroundaround thethe site,site, considering
considering its
its random
random nature.
nature. This
This procedure
procedure cancan bebe described
described ininthe following four steps:thethe following
following four
four steps:
steps:
1. Identification of earthquake sources such as active faults, which may affect the study

1. Identification of earthquake sources such as active faults, which may affect the study area.
1.
Identificationofsources
such
which
may
the
Characterize
the probabilityof faults,
potential
rupturelocations
withinarea.
the
1. area.
Identificationof earthquake
earthquake
sourcesdistribution
such asas active
activefaults,which
may affectaffectthe study
study
area.
Characterize the probability distribution of potential rupture locations within the source.
Characterize
source.
Characterize thethe probability
probability distribution
distribution ofof potential
potential rupture
rupture locations
locations within
within thethe source.
source.
2. Characterization of the seismicity of each source zone using a recurrence relationship, which
which
Characterizationofeachsourcezone
using
aa recurrence
relationship,which
2. Characterization
Characterization ofoftheseismicity
of of
each
sourcezonezoneusingusing
recurrence
relationship,
2.2.
ofthe
theseismicity
seismicity
eachsourcea recurrence
relationship,
specifies the average rate at which an earthquake of some size will be exceeded.
specifies
therateearthquakeofwill
exceeded.
which
specifies
the averagerate atan
an earthquakeof somewill be exceeded.
specifies
the average
averagerate at
at whichwhich
anwhichearthquakeof somesome size
size
will bebesizeexceeded.
3. Estimation of the ground motion produced at the site by earthquakes of any possible size
3. Estimation
groundmotionproducedatsitebyearthquakesofpossiblesize
Estimation ofof thethegroundmotionproducedatatthe
the
site
byby
earthquakesof anyany
possiblesize
3.3. Estimation
thegroundpoint
motionproduced
thesiteearthquakesof anypossibleoccurring atofanypossiblein eachsource zone
using
predictive
relationships.
occurring
at
point
zone
predictive
relationships.
occurringat anyany possible
possiblepoint inin eacheachinsource
sourcezone using
using
predictive
relationships.
occurring
any possible
eachmotion
sourcezone
usingwill
predictive
relationships.
4. size
Obtaining
the atprobability
that point
the groundparameter
be exceeded
during a
4.
Obtainingtheprobability
thatthegroundmotionparameter
willbeexceededduring
4.
Obtainingtheprobability
thatthegroundmotionparameter
willbeexceededduring aaa
4. Obtaining
the probability
that the ground motion parameter will be exceeded during
particular time
period.
particularparticular time
time period.
period.

particular time period.

2.11 Local Site effects and Site Response Study
2.11
2.11 Local
Local Site
Site effects
effects andand Site
Site Response
Response Study
Study
Site response analysis aims at determining the response of a soil deposit to the motion of the
Site
Site response
response analysis
analysis aims
aims at
at determining
determining thethe response
response ofof aa soil
soil deposit
deposit toto thethe motion
motion ofof thethebedrock immediately beneath it. The overburden stress plays a very important role inbedrock
bedrock immediately
immediately beneathbeneath it.
it. TheThe overburden
overburden stressstress plays
plays aa very
very important
important rolerole inin
determining the characteristics of the ground surface motion thus emphasizing the need for
determining
determining thethe characteristics
characteristics ofof thethe groundground surface
surface motion
motion thus
thus emphasizing
emphasizing thethe needneed forforground response analysis. A number of techniques have been developed for ground response
groundground response
response analysis.
analysis. A
A numbernumber ofof techniques
techniques have
have been
been developed
developed forfor groundground response
response
analysis. These techniques can be grouped as one-, two-, and three-dimensional analyses
analysis.
analysis. These
These techniques
techniques cancan bebe groupedgrouped asas one-,one-, two-,
two-, andand three-dimensional
three-dimensional analyses
analysesaccording to the dimensionality of the problems they can address. A one-dimensional method
accordingtothedimensionalityoftheproblems
theycanaddress.
A
one-dimensional
according to the dimensionality of the problems they can address. A one-dimensional method
methodcan be used if the soil structure is essentially horizontal.
cancan bebe usedused if
if thethe soil
soil structure
structure isis essentiallyessentially horizontal.
horizontal.
2.11.1 Assessment of Site Amplification
2.11.1
2.11.1 Assessment
Assessment ofof SiteSite Amplification
Amplification
For Seismic Microzonation, obtaining a proper understanding of the local subsurface
For
For Seismic
Seismic Microzonation,
Microzonation, obtaining
obtaining aa proper
proper understanding
understanding ofof thethe local
local subsurface
subsurface
conditions and to evaluate ground shaking effects is essential. The effect of local soil
conditions
is essential.
The effecteffect ofof local
local soil
conditions andand toto evaluate
evaluate groundground shaking
shaking effects
effects isessential. The
soil
conditions on the amplitude and frequency content of earthquake motions has been theconditions
conditions onon thethe amplitude
amplitude andand frequency
frequency content
content ofof earthquake
earthquake motions
motions has
has been
been thethesubject of considerable interest and research in recent years. Physically the problem is tosubject
subject ofof considerable
considerable interest
interest andand researchresearch inin recentrecent years.
years. Physically
Physically thethe problem
problem isis totopredict the characteristics of the seismic motions that can be expected at the free surface (orpredict
predict thethe characteristics
characteristics ofof thethe seismic
seismic motions
motions thatthat cancan bebe expected
expected at
at thethe freefree surface
surface (or(orat any depth) of a soil stratum. Mathematically the problem is one of wave propagation in a
at
at anyany depth)
depth) ofof aa soil
soil stratum.
stratum. MathematicallyMathematically thethe problem
problem isis oneone ofof wavewave propagation
propagation inin aacontinuous medium. If the medium is linearly elastic and the geometry is relatively simple,
continuous
continuous medium.
medium. If
If thethe medium
medium isis linearlylinearly elastic
elastic andand thethe geometrygeometry is
is relatively
relatively simple,
simple,analytical solutions can be obtained for any kind of waves. In practice, since the wave content
analyticalanalytical solutions
solutions cancan bebe obtained
obtained forfor any
any kindkind ofof waves.
waves. In
In practice,practice, since
since thethe wave
wave content
content
91 31
91
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March 2010of a potential earthquake is hard to predict, solutions are often limited to the simple case ofshear wave propagating vertically.

Many results for this case have been presented, and a discrete model with lumped masses andsprings, based on a finite difference formulation, has enjoyed great popularity among
practicing engineers. The continuous and the discrete formulations are equivalent. This partof the report describes the use of a one-dimensional wave propagation program to develop a
microzonation map of Coxs Bazar District.

When P and S wave reach the ground surface, most of their energy is reflected back in to thecrust, so that surface is affected simultaneously by upward and downward moving waves. For
this reason considerable amplification of shaking typically occurs near the surface andenhances the shaking damages at the surface. Different types of ground affected by the same
earthquake waves may vary in their severity of ground shaking and consequent
destructiveness by one or more degrees of intensity.

Certain building types are more vulnerable to different frequencies of ground motion
vibration than others. Seismic micro zoning can show the frequency content of vibration due
to different local ground condition. It can be used to ensure that a match does not occur
between buildings vulnerable to certain frequencies of vibration and ground conditions thatare likely to vibrate in that frequency range and thus avoiding building being damaged byresonance effect in zones where the ground is likely to vibrate in certain frequency ranges.
Buildings should be designed either to have frequencies of natural vibration well outside thecritical range or to be designed for the much higher seismic forces they are likely toexperience. The frequency map could be used to impose restrictions on the types of building
structures that may have similar frequency.

2.11.2 Methodology Review
Several methods for evaluating the effect of local soil conditions on ground response during
earthquake are presently available. Most of these methods are based on the assumptions thatthe main response in a soil deposit are caused by the upward propagation of shear waves from32

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the underlying rock formation. Analytical procedures based on this concept incorporating
non-linear soil behavior, have been shown to give results in good agreement with fieldobservations in a number of cases. Accordingly they are found in increasing use inearthquake engineering for predicting responses within soil deposits and the characteristics ofground surface motions.
The analytical procedure generally involves the following steps:
Determination of the characteristics of the motions likely to develop in the rockformation underlying the site, and selection of an accelerogram with thesecharacteristics for use in the analysis: The maximum acceleration, predominant period, andeffective duration are the most important parameters of an earthquake motion. Empirical
relationships between these parameters and the distance from the causative fault to the site
have been established for different magnitude of earthquakes (Gutenberg and Richter, 1954,
Seed et al., 1969, Schnable et al., 1972). A design motion with the desired characteristics canbe selected from the strong motion accelerograms that have been recorded during previous
earthquakes (Seed and Idriss, 1969) or from artificially generated accelerograms (Housner
and Jennings, 1964).

Determination of the dynamic properties of the soil Deposit: Average relationships
between the dynamic shear moduli and damping ratios of soils, as functions of shear strain
and static properties; have been established for various soil types (Hardin and Drnevich, 1970,
Seed and Idriss, 1970). Thus a relatively simple testing program to obtain the static properties
for use in these relationships will often serve to establish the dynamic properties with asufficient degree of accuracy. However, more elaborate dynamic testing procedures are
required for special problems and for cases involving soil types for which empirical
relationships with static properties have not been established.
Computation of the response of the soil deposit to the base rock motion: A one
dimensional method of analysis can be used if the soil structure is essentially horizontal.
Programs developed for performing this analysis are in general based on either the solution to
the wave equation (Kanai, 1951) or on a lumped mass simulation (Idriss and Seed, 1968).
More irregular soil deposits may require a finite element analysis.

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March 2010

2.11.3 Method for Amplification Anlysis

One dimensional method of ground response analysis is widely used in earthquake
geotechnical engineering A number of different techniques are available for one-dimensional
response analysis, which can be broadly categorized as linear analysis, equivalent linear
analysis and nonlinear analysis. The most popular method used in professional practice is theequivalent linear approach which is incorporated in the computer program SHAKE. The
program SHAKE is capable of computing the responses for a known motion given
anywhere in a system. It requires three input parameters such as bedrock motion, dynamic
material properties and site specific soil properties The peak surface acceleration, groundresponse spectrum and period of soil column are obtained as output from this analysis. The
accelerograms measured on a known soil deposit can be used to predict underlying rockmotions using SHAKE, which, in turn, can be used to obtain the surface motion for othersoil deposits as shown in Fig. 2.13 (after Schnable et al., 1971). The rock motion is assumed
not to vary within a region. The program incorporates non-linear soil behavior, the effect of
the elasticity of the base rock and systems with variable damping.

a. Theory to the Program: The theory (behind SHAKE) considers the responses
associated with vertical propagation of shear waves through the linear visco-elastic
system shown in Figure 2.14. The system consists of N horizontal layers which
extend to infinity in the horizontal direction and has a half space as the bottom layer.
Each layer is homogeneous and isotropic, and is characterized by the thickness, h,mass density, , shear modulus, G, and damping factor, .

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Figure 2.13: Schematic representation of procedure for computing effects of local soil conditions on
ground motions (Schanbel et al., 1971)

Figure 2.14: One dimensional wave propagation system (Schanbel et al., 1971)

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March 2010

2.11.4 Description of the Program SHAKE
Program SHAKE computes the responses in a system of homogeneous, visco-elastic layers of
infinite horizontal extent subjected to vertically travelling shear waves. The system is shownin Figure 2.14. The program is based on the continuous solution to the wave- equation
adapted for use with transient motions through the fast Fourier transform algorithm. The
nonlinearity of the shear modulus and damping is accounted for by the use of equivalentlinear soil properties using an iterative procedure to obtain values for modulus and damping
compatible with the effective strains in each layer. The following assumptions are implied in
the analysis:
The soil system extends infinitely in the horizontal direction. Each layer in the system iscompletely defined by its value of shear modulus, critical damping ratio, density, andthickness. These values are independent of frequency.
The responses in the system are caused by the upward propagation of shear waves fromthe underlying rock formation.
The shear waves are given as acceleration values of equally spaced time intervals. Cyclic
repetition of the acceleration time history is implied in the solution.
The strain dependence of modulus and damping is accounted for by an equivalent linear
procedure based on an average effective strain level computed for each layer.
The program is able to handle systems with variation in both moduli and damping, and takes
into account the effect of the elastic base. The motion used as a basis for the analysis, theobject motion, can be given in any one layer in the system and new motions can be computedin any other layer. The set of operations can be performed by the program:
Read the input motion, find the maximum acceleration, scale the values up or down, andcompute the predominant period.
Read data for the soil deposit and compute the fundamental period of the deposit.
Compute the maximum stresses and strains in the middle of each sub-layer and obtainnew values for modulus and damping compatible with a specified percentage of the
maximum strain.
Compute new motions at the top of any sub-layer inside the system or outcropping fromthe system.

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2.11.5 Use of SPT-value for Shear Wave Velocity
There are several empirical relations correlating the SPT-N value and Shear Wave Velocity(Vs) as Shown in Table 2.6. The Standard Penetration Test (SPT) has been widely used toinvestigate soil deposit for identifying subsurface soil profiles. The empirical relationships
presented here can be used to convert SPT-N value into Shear Wave Velocity which is needed
as one of the input parameters for the program SHAKE.
Table 2.6: Empirical Relations Correlating SPT-N value and Shear Wave Velocity(After TC4, 1993)
Researchers

Equation

Imai and Yoshimura (1970)

Vs = 76 N0.33

Ohba and Toriumi (1970)

Vs = 84 N0.31
Vs = 69 N0.17 D0.2 F1 F2
Where
F1 = 1.0 (H);

Ohta and Goto (1978)

F2 = 1.00 (clay)= 1.3 (P);= 1.09 (f. sand)= 1.07 (m. sand)= 1.14 (c. sand)= 1.15 (g. sand)= 1.45 (gravel)

Vs = a Nb

Where
Imai (1977)

a = 102;b = 0.29 (H. clay)= 81;= 0.33 (H. sand)= 114= 0.29 (P. clay)= 97= 0.32 (P. sand)Okamoto et al. (1989)

Vs = 125 N0.3 (P. clay)

Tamura and Yamazaki (2002)

Vs = 105 N0.187 D0.179

Here,
Vs = Shear Wave Velocity (m/s); N = Corrected SPT blow countD = Depth (m); H = Holocene; P = Pleistocene
f = Fine; m = Medium; c = Coarse; g = Gravel
97 37

March 20102.12 Liquefaction Analysis
Soil liquefaction is a phenomenon in which a soil below the ground water table loses a
substantial amount of strength due to pore pressure generation from strong earthquake groundshaking. Earthquake shaking induces shear stresses in the soil that cause the saturated
cohesion less granular soil particles to rearrange and excess pore pressures to build up.
Liquefaction can occur in moderate to major earthquakes resulting in severe damages tostructures. It can have a significant and sometimes devastating effect on buildings supported
on the upper soil layers constructed without consideration of its consequences of liquefaction.
The damaging effects of soil liquefaction have been well recognized since the Niigata andAlaska earthquakes of the early 1960s. The types of failures associated with liquefaction
include:(i).

Sinking or overturning of the structures,(ii).

Excessive differential settlement of the structures,(iii).

Sand boils; and(iv).

Surface lateral spreading.

2.12.1 Causes of Soil Liquefaction

The general trend on understanding about the basic causes of liquefaction of sands is a quite
qualitative measure. If a loose saturated sand deposit is subjected to ground vibrations, it
tends to compact and decrease in volume. The effective stress in the sand deposit is equal tothe difference between the overburden pressure and the pore water pressure. If drainage isunable to occur, the tendency to decrease in volume results in an increase in pore waterpressure. So, with increasing oscillation, the pore water pressure will be equal to the
overburden pressure causing the effective stress to become zero. Since the shear strength of acohesionless soil is directly proportional to the effective stress, the sand loses its strengthcompletely and develops a liquefied state.

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In more quantitative terms, it is now generally believed that the basic cause of liquefaction insaturated cohesionless soil during earthquake is the buildup of excess hydrostatic pressure
due to the application of cyclic shear stress induced by the ground motions. These stresses are
generally considered to be due primarily to upward propagation of shear waves in a soil
deposit; although other forms of wave motions are also expected to occur. Thus, soil elements
can be considered to undergo a series of cyclic stress conditions, the stress series being
somewhat random in pattern but nevertheless cyclic in nature.

There are several factors that influence liquefaction such as the geologic history of thedeposit, the depth of ground water table, the grain size distribution, the density of soil,
duration of earthquake, amplitude and frequency of shaking, distance from epicenter,cohesion of the soil and permeability of the layer and ground slope. The liquefaction hazards
are commonly associated with saturated sandy and silty soils having low plasticity anddensity.

2.12.2 Methodology for Liquefaction Analysis
Liquefaction susceptibility is a measure of a soils inherent resistance to liquefaction, and canrange from not susceptible, regardless of seismic loading, to highly susceptible, which meansthat very little seismic energy is required to induce liquefaction. There are a number ofdifferent methods by which the potential for liquefaction of a soil can be evaluated. The typesof methods can be classified into four categories:
Category-1: Evaluation of liquefaction potential roughly based on topographical andgeological information
Category-2: Evaluation of liquefaction potential from N-value and grain size distribution data,and estimates of peak surface acceleration.
Category-3: Evaluation of liquefaction potential from laboratory cyclic shear testing of
undisturbed samples, in light of dynamic response analysis.
Category-4: Evaluation of liquefaction potential by conducting in-situ cyclic or blasting tests,or laboratory shaking table tests.

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Because of their simplicity, methods that fall in the first and second category are generally
useful for formulating microzonation maps of liquefaction potential for wide areas. Methods
in the last two categories provide a more rigorous examination of liquefaction at a single site,
but are too tedious and costly for survey-type applications. In this study, the second
procedure was adopted to formulate microzonation map of liquefaction potential.
The second procedure involves a more direct use of geotechnical data, such as SPT-N value
and means particle diameter, and estimates of peak surface acceleration (Seed and Idriss,1971). A liquefaction resistance factor FL, is calculated which is used to evaluate theliquefaction potential index, IL. The method is briefly explained below.
2.12.3 Liquefaction Potential Based On SPT N-Values
The first step in calculation of liquefaction potential is to determine whether the soil has thepotential to liquefy during the earthquake. This analysis is usually carried out by using
simplified empirical procedure, originally developed by Seed and Idriss (1971). This method
has been used here to evaluate the Liquefaction Resistance Factor, FL which can also be
termed as Factor of Safety. It is the most common and traditional method that uses
correlations between the liquefaction characteristics of soils and the Standard penetration
Tests or N-value along with other parameters such as grain size distribution curves of soils,
overburden pressure, and estimated peak surface acceleration. The assessment of theliquefaction resistance factor at any depth involves comparison of the predicted cyclic stressratio (t/ ´0) that would be induced by a given design earthquake (L) with the cyclic stressratio required to induce liquefaction (R). For this method, FL is calculated for a given depth ofsoil layer by the following formula.
FL

R
L

(2.1)

Liquefaction is assumed to occur at that depth if FL is less than 1.0. Here, R is the in-situ
capacity of soil to resist liquefaction expressed by Cyclic Resistance Ratio (CRR) forearthquake of magnitude 7.5 and L is the earthquake load induced by a seismic motion
expressed by Cyclic Stress Ratio (CSR). Cyclic Resistance Ratio for earthquake of magnitude
7.5 is determined based on corrected SPT and mean soil particle size (Seed et al. 1983).

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Table 2.7: Magnitude Scaling Factor after Seed and Idriss (1983)

Earthquake Magnitude

MSF

6

1.32

6.75

1.13

7.5

1.00

8.5

0.89

Magnitude Scaling Factor (MSF), obtained from Table 2.7, is used to determine the Factor of
Safety against Liquefaction for earthquakes other than that of magnitude 7.5 and calculated as

FS FL

CRR 7.5
MSF
CSR

(2.2)

The shear stresses developed at any point in a soil deposit during an earthquake appear to be
due primarily to the vertical propagation of shear waves in the deposit. If the soil column
above a soil element at depth h behaved as a rigid body, the maximum stresses on the soil
element would behg( max ) r

smax

0

g

smax

(2.3)

where

g

o

=

total overburden pressure

Smax

=

estimated peak surface acceleration (in percentage of g)=

Unit weight of the soil=

acceleration due to gravity;

Figure 2.15
thetheprocedure
for fordetermining
cycliccyclic
shear shear
stress stresson a soil
duringFigure2.15illustrates
illustrates
procedure
determining
on elementa soil element

duringground andshaking
2.16theillustrates
determining
maximumground shaking
Figureand
2.16Figure
illustrates
procedurethe
for procedure
determiningfor
maximumshear stress.
shear stress.

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Figure 2.15: Cyclic shear stresses on a soil element during ground shaking(Iwasaki, 1982)

Figure 2.16: Procedure for determining maximum shear stress(Seed et al. 1983)

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Because the soil column behaves as a deformable body, the actual shear stress at depth h,(τmax)d, as determined by the ground response analysis will be less than (τmax)r and might
be expressed by(τmax)d, = rd (τmax)r

(2.4)

Where
rd = a stress reduction factor with a value less than 1 given by (1‐ 0.015z) in whichz = depth of ground surface in meters.

Computations of the value of rd for a wide variety of earthquake motions and soil
conditions having sand in the upper 50 ft. have shown that rd generally falls within therange of values shown in Figure 2.17. It may be seen that in the upper 30 or 40 ft., thescatter of the results is not so great and, for any of the deposits, the error involved inusing the average values shown by the dashed line would generally be less than about 5%.
Thus to a depth of about 40 ft., a reasonably accurate assessment of the maximum shear
stress developed during an earthquake can be made for the relationship given in equation(3.3) by using values of rd to be taken from the dashed line in Figure 2.17.
The actual time history of shear stress at any depth in a soil deposit during an earthquake
will have an irregular form such as that shown in Figure 2.18. From such relationships it isnecessary to determine the equivalent uniform average shear stress. By appropriate
weighting of the individual stress cycles, based on laboratory test data, this determination
can readily be made. However, after making these determinations for a number ofdifferent cases it has been found that with a reasonable degree of accuracy, the average
equivalent uniform shear stress, τav, is about 65% of the maximum shear stress, τmax.
Combining this result with the above expression for τmax, the average cyclic stress ratio(τav / б´0) induced by an earthquake is given by the expression (Seed et al., 1983)
CSR = L =⎞⎛ σ ⎞⎛ατ av= 0.65 ⎜⎜ s max ⎟⎟⎜⎜ 0 ⎟⎟ rd
σ 0′⎝ g ⎠⎝ σ 0′ ⎠(2.5)

Where,
б´0 = effective overburden pressure43March 2010

The cyclic stress ratio required to cause liquefaction has been evaluated using empirical
relationship between cyclic stress ratio and N values. This curve is presented in Figure 2.19.

Figure 2.17: Range of Values of rd for different soil profiles (Seed et al., 1983)

Figure 2.18: Time history of shear stresses during earthquake (Seed et al., 1983)44

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Figure 2.19: Correlation between field liquefaction behavior of Silty sands under level groundconditions and standard penetration resistance (after Seed et al., 1983)

Since the standard penetration resistance, N, measured in the field actually reflects theinfluence of the soil properties and the effective confining pressure, it has been founddesirable to eliminate the influence of confining pressure by using a normalized penetration
resistance N1, where N is the measured penetration resistance of the soil under an effective
overburden pressure of 1 ton per sq. ft. Thus, before using the graph in Figure 2.20,
normalized to the field SPT-N value is estimated as follows:

N1 = CN . N(2.6)

Where,
N1= modified N valuesCN= a correction factor

The correction factor, CN was provided by Murthy (1991) and presented here as Figure 2.20.

105 45

March 2010

Figure2.20:
2.20:Recommen
Recommended
Curvesfor
forCorrection
CorrectionFactor
Factorfrom
fromEffective
EffectiveOverburde
Overburden
Pressure(after(afterFigureded Curves
n Pressure
Murthy,1991)
1991)
Murthy,Theseverity
severityof
offoundation
foundationdamage
damagecaused
causedby
bysoilsoilliquefactio
liquefaction
dependstotoaagreat
greatextent
extentononThen depends
theseverity
severityofofliquefactio
liquefaction,
whichcannot
cannotbe
beevaluatedevaluatedsolely
solelyby
bythe
theFFLL. .Generally
Generallyspeaking,speaking,
then, whichliquefaction
underthethefollowing
followingcondition
conditiontends
tendstotobe
besevere:severe:liquefaction under
Theliquefiedliquefiedlayer
layerisisthick
thick
1.1.The
Theliquefiedliquefiedlayer
layerisisshallow
shallow
2.2.The
TheFFL Lofofthe
theliquefiedliquefiedlayer
layerisisfar
farless
lessthanthan1.00
1.00
3.3.Theordertotoaccountaccountfor
forthese
theseeffects,
effects,thetheJapaneseJapaneseBridge
BridgeCode
Code(Japanese(JapaneseRoad
RoadAssociatio
Association,
InInordern,1991)recommen
recommended
modification
theprocedure
proceduresuggested
suggestedininSeed
Seedetetalal(1983).
(1983).InInthis
this
1991)
ded a amodificati
on totothe
method thethe factor
factor ofof safety
safety values,
values, FFL L (Seed(Seed andand Idriss,
Idriss, 1971)1971) against
against resistanceresistance toto
methodliquefaction
havebeen
beencomputed
computedupuptototop
top2020meters
metersdepth
depthforforallallthe
theboreboreholes
holesandandthesetheseliquefactio
n havevalueshave
havebeen
beensubsequen
subsequently
convertedinto
intoliquefactio
liquefaction
potentialindex
index(I(IvaluesL) given by the
tly converted
n potentialL) given by thefollowingequation
equation(Iwasaki(Iwasakietetal.,al.,1982):
1982):
following46

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IL

20

F(z)w(z)dz

(2.7)

0

Where,F (z)=(1 FL)

for FL 1.0

F (z)

=

0

for FLW (z)=(10  0.5 Z)

for z 20 m

W (z)

=

0

for z >20 m

1.0

The
valueofofliquefactionliquefaction
potential,
IL indicatesa soilismass
is susceptible
to liquefactionthat athat
soil masssusceptible
to liquefaction
if IL > 0. If if
The valuepotential,
IL indicatesvalue
of value
IL is large,
is very
susceptibleliquefaction.
If theof Ithelarge,
the soilis veryfor
susceptible
for liquefaction.
Ithe
L>0.
L is soil

Severity of liquefaction is then expressed as shown below:
IL

= 0,

No Liquefaction= 0-5,

Low Liquefaction= 5-15,Moderate Liquefaction= >15,High Liquefaction

IL has been used to express the measure of liquefaction potential for a particular location andfor further zonation of the area based on a particular range of this index. Table 2.8 shows theinterpretation of liquefaction potential in terms of intensity and ground susceptibility.
Table 2.8: Summary of the Liquefaction Potential Index (Iwasaki et al., 1986)
Liquefaction

Criteria

Explanation

PotentialHigh

15 < IL

Moderate

5 < IL 15

Low

0< IL 5

Very low

IL=0

Ground Improvement is indispensable
Ground Improvement is required. `Investigationof important structures is indispensable
Investigation of important structures is required
No measure is required

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March 20102.15 Landslide
A landslide is a geological phenomenon which includes a wide range of ground movement,such as rock falls, deep failure of slopes and shallow debris flows. Although the action ofgravity on an over-steepened slope is the primary reason for a landslide, there are othercontributing factors affecting the original slope stability. Typically, pre-conditional factors
build up specific sub-surface conditions that make the area/slope prone to failure, whereas theactual landslide often requires a trigger before being released.
Landslides and other gravity-stimulated mass movements are a continual source of concern
for geotechnical engineers and engineering geologists throughout the world, particularly ingeologically active regions. They occur worldwide and are described as sudden, short-lived
geomorphic events that involve the rapid to slow descent of soil or rock in sloping terrains.
They can occur on any terrain give the right conditions of soil, moisture and the angle ofslope. Risks of landslides are enhanced in the tropics, where thick, loose residual soil, theresult of deep weathering, can be easily eroded.
2.15.1 Types of Landslides
The term "landslide" describes a wide variety of processes that result in the downward andoutward movement of slope-forming materials including rock, soil, artificial fill, or a
combination of these. The materials may move by falling, toppling, sliding, spreading, or
flowing. Figure 2.21 shows a graphic illustration of a landslide, with the commonly accepted
terminology describing its features.

The various types of landslides can be differentiated by the kinds of material involved and themode of movement. A classification system based on these parameters is shown in Table 2.9.

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Table 2.9: Types of landslides, Abbreviated version of Varnes', 1978 classification of slope
movements (National Atlas, 2008)

The most common types of landslides are described as follows and are illustrated in Figure
2.22.
Slides: The term Slide refers to mass movements, where there is a distinct zone of weakness
that separates the slide material from more stable underlying material. The two major types ofslides are rotational slides and translational slides.
Rotational slide is a slide in which the surface of rupture is curved concavely upward and theslide movement is roughly rotational about an axis that is parallel to the ground surface andtransverse across the slide (Figure 2.22A).
In Translational slide, the landslide mass moves along a roughly planar surface with little
rotation or backward tilting (Figure 2.22B).
A block slide is a translational slide in which the moving mass consists of a single unit or a
few closely related units that move downslope as a relatively coherent mass (Figure 2.22C).

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Falls: Falls are abrupt movements of masses of geologic materials, such as rocks andboulders, that become detached from steep slopes or cliffs (Figure 2.22 D).
Topples: Toppling failures are distinguished by the forward rotation of a unit or units aboutsome pivotal point, below or low in the unit, under the actions of gravity and forces exerted
by adjacent units or by fluids in cracks (Figure 2.22 E).
Flows: There are five basic categories of flows that differ from one another in fundamental
ways.
a. Debris flow: A debris flow is a form of rapid mass movement in which a combination ofloose soil, rock, organic matter, air, and water mobilize as a slurry that flows downslope(Figure 2.22 F). Debris flows include <50% fines. Debris flows are commonly caused byintense surface-water flow, due to heavy precipitation or rapid snowmelt, that erodes andmobilizes loose soil or rock on steep slopes. Debris flows also commonly mobilize fromother types of landslides that occur on steep slopes, are nearly saturated, and consist of a large
proportion of silt- and sand-sized material. Debris-flow source areas are often associated withsteep gullies, and debris-flow deposits are usually indicated by the presence of debris fans at
the mouths of gullies. Fires that denude slopes of vegetation intensify the susceptibility ofslopes to debris flows.
b. Debris avalanche: This is a variety of very rapid to extremely rapid debris flow (Figure
2.22 G).
c. Earthflow: Earthflows have a characteristic "hourglass" shape (Figure 2.22 H). The slope
material liquefies and runs out, forming a bowl or depression at the head. The flow itself iselongate and usually occurs in fine-grained materials or clay-bearing rocks on moderateslopes and under saturated conditions. However, dry flows of granular material are also
possible.
d. Mudflow: A mudflow is an earthflow consisting of material that is wet enough to flow
rapidly and that contains at least 50 percent sand-, silt-, and clay-sized particles. In someinstances, for example in many newspaper reports, mudflows and debris flows are commonlyreferred to as "mudslides."50

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e. Creep: Creep is the imperceptibly slow, steady, downward movement of slope-forming soil
or rock. Movement is caused by shear stress sufficient to produce permanent deformation, but
too small to produce shear failure. There are generally three types of creep: (1) seasonal,
where movement is within the depth of soil affected by seasonal changes in soil moisture andsoil temperature; (2) continuous, where shear stress continuously exceeds the strength of thematerial; and (3) progressive, where slopes are reaching the point of failure as other types ofmass movements. Creep is indicated by curved tree trunks, bent fences or retaining walls,
tilted poles or fences, and small soil ripples or ridges (Figure 2.22 I).
Lateral spreads: Lateral spreads are distinctive because they usually occur on very gentle
slopes or flat terrain (Figure 2.22 J). The dominant mode of movement is lateral extension
accompanied by shear or tensile fractures. The failure is caused by liquefaction, the process
whereby saturated, loose, cohesionless sediments (usually sands and silts) are transformed
from a solid into a liquefied state. Failure is usually triggered by rapid ground motion, such asthat experienced during an earthquake, but can also be artificially induced. When coherent
material, either bedrock or soil, rests on materials that liquefy, the upper units may undergo
fracturing and extension and may then subside, translate, rotate, disintegrate, or liquefy andflow. Lateral spreading in fine-grained materials on shallow slopes is usually progressive.
The failure starts suddenly in a small area and spreads rapidly. Often the initial failure is aslump, but in some materials movement occurs for no apparent reason. Combination of two
or more of the above types is known as a complex landslide.

Figure 2.21: An idealized slump earth flow showing commonly used nomenclature for labeling theparts of a landslide (National Atlas, 2008)

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Figure 2.22: Schematics illustrating the major types of landslide movements (National Atlas,
2008)
2.15.2 Landslide in the South Eastern Bangladesh

Landslide is a regular geologic hazard in Bangladesh, especially in the South-Eastern part ofthe country. The steepness of a hill is the main factor for the movement of the materials thatflow down towards the foot of the hill. Steep slope push down debris or mud converting
gravitational energy into kinetic energy. A natural hill is a stable surface of the earth systemhaving a balance of its components. Every natural hill is maintaining its stability by natural
condition of the system that sometimes disturbed by improper interactions of human being.
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Landslide induced by human activities has become very common in the hilly areas ofsoutheastern Bangladesh, especially in Bandarban, Rangamati, Khagrachhari and Cox's Bazar.
Illegal hill-cutting due to rampant building has left some 70,000 (IRIN, 2008) people at riskof landslides in 18 sub-districts of the hill districts, as well as the city of Chittagong, warned
specialists. Every year especially in the rainy season landslides take place in both natural andman-induced slopes. Considerable number of buildings, roads and other infrastructures aredamaged and valuable lives are lost in these incidents. The loss of lives and properties due toLandslide events in Coxs Bazar is also very significant. In 15th June of 2003 (International
Landslide Centre, 2006) total 6 casualties were reported at Coxs Bazar due to Landslides
caused by heavy rain. The earthquake of July 30, 2003(Natural Hazards, 2007) with amagnitude of 5.9 hit the Chittagong area causing casualties of six persons in Cox's Bazar bylandslide. In September 2006 landslide triggered by heavy rain killed two children andinjured six people in the village Rajarkol. Nineteen people died in landslides in Cox's Bazar
district in the first half of July 2008 (International Herald Tribune, 2006) alone. On 14 July
two people died under a mudslide at Himchhari. On August 11, 2008 three members of afamily were buried alive as their mud-hut collapsed in Coxs Bazar. Very recently, on July 31,
2009, ten people were killed in Bandarban due to landslide (South Asian Media Net, 2009).
Types, major nature and processes that cause landslides in Bangladesh are 1) removal oflateral support: a) erosion by rivers, b) previous slope movements such as slumps that create
new slopes, c) human modifications of slopes such as cuts, pits, and canals; 2) addition ofweight to the slope: a) accumulation of rain, b) increase in vegetation, c) construction of fill,d) weight of buildings and other structures, e) weight of water from leaking pipelines, sewers,
canals, and reservoirs; 3) earthquakes; 4) regional tilting; 5) removal of underlying support:a) undercutting by rivers and waves; b) swelling of clays; 6) anthropogenic activities as jhum
cultivation
Since Coxs Bazar, the study area for this dissertation, is one of the most landslide prone
areas of the country, assessment of landslide potential of Coxs Bazar has become very
essential. Indiscriminate Hill cutting is one of the major causes of landslide in this area. Landslide may also be caused by earthquake in steep hill and loose land of steep periphery. Gentle
angle or slope is mostly absent in the hills of Coxs Bazar. Rock strata in this area are mostly
found as soft or brittle sedimentary rocks which may easily be broken or slide. Since Coxs
Bazar is on the threat of probable earthquake events, the hill-tops loosened by any means cancause massive destruction if a moderate to major tremor takes place.
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The southern part of the municipal area is mostly hilly which consists of Dupi Tila Formation(Figure 2.3). Lower hill of the area are mainly underlain by little-consolidated sands andshales of the Dupi Tila formation, which may be from late-Miocence age (Brammer, 1996).
These hills are mainly composed by unconsolidated or little-consolidated beds of sandstones,
siltstones and shales, together with minor beds of limestone and conglomerates. Nature ofparent materials strongly determines the texture of the soils. Shale results heavy silt loam orsilty clay loam subsoil. Soils developed on sandstone have dominant textural class of sandy
loams with occasional loamy sand or loam texture
There also exist hills of Tipam and Bokabil Formation, sparsely in the area. Previous studies
on erosional hazards of Chittagong City (Banglapedia, 2006) disclose that the hills formed of
Dupi Tila Formation is prone to three types of landslides and slope failures which are lateral
spreading movement, rotational and translational movements. Planar or block movement
have been observed to occur in Bokabil Formation and rotational, translational and planar or
block failures occur in Tipam Formation.
The major landslide occurrences in and around Coxs Bazar municipal area have been listed
in Appendix C (Banglapedia, 2006).
2.15.3 Landslide Hazard Analysis Method
The effects of earthquake-induced landslide have received much less research attention than
the seismic effects of soil amplification and liquefaction. Landslide hazard is typically very
difficult to quantify because landslide come in many forms and are caused by a variety ofprocesses. The local site factors that affect landslides generally include slope stability,
geology, slope angle, hydrological conditions, vegetation, land use, and severity of theearthquake. Most of these factors are necessary for the investigation of an individual slope,
but for seismically induced landslide analysis on a broad regional basis, magnitude of theseismic event, and distance from the seismic source (Hansen and Franks, 1991).
As with liquefaction, regional landslide hazard has traditionally been analyzed in a qualitative
manner utilizing expert opinion, although recently more quantitative geotechnical methods
have been proposed. The qualitative methods typically produce microzone maps indicating
the relative susceptibility of various regions to landslides with no investigation into thepossible triggering mechanisms for the land movement. The maps often result from an expert

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analysis of regional factors such as previous landslide locations, geologic deposits, andtopography.
The complicated nature of the landslide process has made regional estimates of this local site
effect very difficult to define quantitatively. Most of the recent research in this field has
focused on determining the critical level of a given ground motion parameter that will trigger
landslide in various geologic deposits. Wieczorek, et al. (1985) models a landslide as atranslational failure in an infinite slope with a depth of 3 meters. They define three classes ofgeological units, assign shear strength parameters for each class, and then perform stability
analyses using dry and saturated conditions to obtain the static factor of safety (FS) for eachclass. Based on the static FS, the critical acceleration to begin the process of slope failure, ac,
is computed as
ac =(FS 1) g sin

Where,(2.8)= slope angle
FS = factor of safety determined from a static slope stability analysis
G = acceleration of gravity

These ac values are compared to the regional estimates of surface peak ground acceleration to
give a prediction for the occurrence of damaging earthquake-induced landslides in the area.
There have been very few implementations of quantitative landslide hazard models in the
GIS environment instead, a qualitative approach utilizing regional maps showing relative
susceptibility of landslides in various geologic deposits will be used to describe earthquakeinduced landslide hazard.
2.15.4 Slope Stability Analysis
The evolution of slope stability analyses in geotechnical engineering has followed closely thedevelopments in soil and rock mechanics as a whole. Slopes either occur naturally or are
engineered by humans. Slope stability problems have been faced throughout history whenhuman or nature has disrupted the delicate balance of natural soil slopes. An understanding ofgeology, hydrology, and soil properties is central to applying slope stability principles
properly. Analyses must be based upon a model that accurately represents site subsurface
conditions, ground behavior, and applied loads. Judgments regarding acceptable risk or safety
factors must be made to assess the results of analyses.

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Civil engineers often are expected to make calculations to check the safety of natural slopes,
slopes of excavations and compacted embankments. This check involves determining theshear stress developed along most likely rupture surface and comparing it with the shear
strength of the soil. This process is called slope stability analysis. The most likely rupture
surface is the critical surface that has the minimum factor of safety.
The stability analysis of a slope is difficult to perform. Evaluations of variables such as soil
stratification and its in-place shear strength parameters may prove be a formidable task.
Seepage through the slope and the choice of a potential slip surface add to the complexity ofthe problem. The forces of gravity tends to move soil from high levels to low levels and theforces that resists this action are on account of shear strength of soil. Presence of water
increases weight reduces strength and decreases stability. The factor of safety is therefore
chosen as a ratio of the available shear strength to that required to keep the slope stable.
2.15.5 Common Features of Slope Stability Analysis Methods
Sliding surfaces in landslides are commonly bowl- or dish-shaped in three dimensions. The
widths of the slides are often the same order of magnitude as the down slope length, andstresses parallel to the strike of the ground surface are thought to influence the failure to only
a limited extent. It is common to examine the stability of a series of two-dimensional sectionsin the dip direction and to calculate weights, forces and moments for unit width in the strikedirection, Lodalen, Norway (Sevaldson, 1956). A section through the deepest part of the slide
mass usually gives a conservative estimate of the stability. Averaging techniques (Lambe andWhitman, 1969) are available. Analysis of slides in jointed rock masses must often formallyconsider three-dimensional limiting equilibrium.
Various techniques of slope stability analysis include three broad categories Limit
Equilibrium Methods, Limit Analysis Solutions and Probabilistic Methods. However, Limit
Equilibrium Methods are more commonly used in practice. The basic assumptions of Limit
Equilibrium Methods approach is that Coulombs failure criterion is satisfied along anassumed failure surface, which can be a straight line, an arc of a circle, a logarithmic spiral or
any other irregular surface.

Common Features of Slope Stability Analysis Methods include:

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1. Safety Factor: F = S/Sm where S = shear strength and Sm = mobilized shear resistance.
F = 1: failure, F > 1: safety
2. Shape and location of failure is not known a priori but assumed (trial and error to findminimum F)
3. Static equilibrium (equilibrium of forces and moments on a sliding mass)
4. Two-dimensional analysis

Most Critical Failure Surface: In homogeneous soils relatively unaffected by faults or
bedding, deep seated shear failure surfaces tend to form in a circular, rotational manner. The
stability analysis aims to find the most dangerous, ie., the most critical surface, and using theassumption above, this surface can be found using "trial circles". This provides a basis forseveral methods used to assess the stability of slopes.
The method is as follows:1. A series of slip circles of different radii but the same centre of rotation is considered(Figure 2.23). The Factor of Safety (FoS) for each of these circles against radius isplotted (Figure 2.24), and the minimum FoS is found out.
2. This should be repeated for several circles, each investigated from an array of centres.
The simplest way to do this is to form a rectangular grid from the centres (Figure2.25).
3. Each centre will have a minimum FoS, and the overall lowest FoS from all the centres
shows tha FoS for the whole slope. This assumes that enough circles, with a large
spread of radii, and a large grid of centres have been investigated. Then an overall
failure, surface, with smaller individual ones is also found out. (Figure 2.26).
4. Submerged Slopes: When an external water load is applied to a slope (Figure 2.27),
the pressure it exerts tends to have a stabilising effect on the slope. The vertical andhorizontal forces due to the water must be taken into account in our analysis of theslope.
Assumptions in Limit Equilibrium: Certain assumptions are needed to be made in analysing
slopes using limit equilibrium:1. Assuming a Failure Mechanism: The shape and location of a failure surface rather are
assumed then determining it by analysis.

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2. Assuming Plane-Strain (2-D): 3-D effects (although of course in reality slopes are inthree dimensions) are ignored. By neglecting these effects the analysis becomes
conservative, ie. higher FoS is achieved by taking them into account.
3. Assuming Rigid Block Movement: The soil mass is assumed to be moved as a rigid
block, with the movement only taking place on the failure surface itself.
4. Assuming Uniform Localisation of Shear Stresses: The shear stresses are not usually
uniformly mobilised over the whole length of the failure surface but for the purpose of
the analysis, it assumed that they are.

Factor of Safety: In slope design, and in fact generally in the area of geotechnical engineering,
the factor which is very often in doubt is the shear strength of the soil. The loading is known
more accurately because usually it merely consists of the self-weight of the slope. The FoS is
therefore chosen as a ratio of the available shear strength to that required to keep the slope
stable. A factor of safety is calculated by dividing the forces resisting movement by the forces
driving movement. If the forces available to resist movement are greater than the forces
driving movement, the slope is considered stable. When performing stability analyses usuallymore interest is put in the stability of the un-failed soil, and in determining a factor of safety,
F, for the un-failed soil. To determine the factor of safety it is assumed that only some part of
the frictional and cohesive forces have been mobilized, so that on the assumed failure plane
the soil is not at a state of failure. Guidelines for limit equilibrium of a slope are given astable 2.10.
Table 2.10: Guidelines for limit equilibrium of a slope (Connolly, 1997)
Factor of Safety
Details Of Slope<1.0
Unsafe1.0-1.25 Questionable safety
Satisfactory for routine cuts and fills,
1.25-1.4
Questionable for dams, or where failure would be catastrophic>1.4
Satisfactory for dams

For highly unlikely loading conditions, factors of safety can be as low as 1.2-1.25, even fordams. e.g. situations based on seismic effects, or where there is rapid drawdown of the waterlevel in a reservoir.

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2.15.6 Methodology Review for Slope Stability Analysis
This section aims at presenting the methods of slope stability analysis, which are commonly
available. The methods of analysis can be categorized as follows:

A. Granular Soils:
The C'=0 Method
B. Cohesive Soils:
Circular Failure Surface
Method of Slices
Fellenius' Method
Bishop's Method
Non-Circular Failure Surface
Janbu's Method
Infinite Slope Method
Stability Charts
Few of the methods are summarized in the following paragraphs.

Method of Slices: The method of slices is a method for analyzing the stability of a slope in
two dimensions. The sliding mass above the failure surface is divided into a number of slices.
The forces acting (Figure 2.28) on each slice are obtained by considering the mechanicalequilibrium for the slices. It is assumed that the arc is circular, radius R, centre is O. The soil
mass above a trial failure surface is divided into slices by vertical planes. Each slice is taken
as having a straight line base. The Factor of Safety of each slice is assumed to be the same,
implying mutual support between the slices, ie., there must be forces acting between theslices. To go about finding the FoS, the problem is now statically indeterminate and someassumptions are needed to be made about the interslice forces. This part is better performed
by Fellenius Method.

Fellenius Method: This is a modified version of the Method of Slices.
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Here it is assumed that E1 =E2 = X1 =X2 (Figure 2.29)
Then, N = W cos and S = 1/F [c l +( Wcos  ul) tan ]Using Moment Equilibrium,
Wx = SRWR sin = SR (Figure 2.39)
S = W sin = 1/F [c l +( Wcos  ul) tan ]So, F =

1/F [c l +( Wcos  ul) tan ]

(2.8)

W sin

Bishop's Method: The Modified (or Simplified) Bishop's Method is a method for calculating
the stability of slopes. It is an extension of the Method of Slices. By making some simplifying
assumptions, the problem becomes statically determinate and suitable for hand calculations.
It is assumed that the forces on the sides of each slice are horizontal.
The method has been shown to produce factor of safety values within a few percent of the"correct" values.

(2.9)
where

(2.10)

Here, c' is the effective cohesion' is the effective internal angle of internal frictionb is the width of each slice, assuming that all slices have the same width
W is the weight of each slice
u is the water pressure at the base of each slice

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As F is on both sides of the equation, it is solved iteratively. An initial value of F is obtainedby carrying the Fellenious Method and multiplying the solution by 1.2. This value isinserted into the right hand side of the equation, and the left hand side value of F is calculated.
This new value is then inserted into the Right hand side and the process is repeated until the
Right hand side = Left hand side.
Janbu's Method: The difficulty in analysing a non-circular failure surface is that it is difficult
to find a single point through which many of the force components act. So, the moment
equilibrium method used for circular surfaces is no longer the most appropriate. Janbu chose
instead to use the force equilibrium method in the analysis. The equation of Factor of Safety
here is followed as Bishops Method. After discovering a certain amount of inaccuracy in thisformula, Janbu decided on a correction factor f0, which should be applied after iteration has
taken place (in Bishops Method):
Fcorrected = f0 * Fiterative

The value of f0 is found from the limiting graphs (Figure 2.30). For this method, it isnecessary to use narrow slices.
Infinite Slope Analysis: The simplest form of sliding surface is a plane parallel to the groundsurface (Figure 2.31). This may be observed in the field as large flake or planar slides innatural hillsides, which are often initiated by softening and weathering processes extending
downwards from the ground surface; by high groundwater pressures; or by toe unloading(Skempton, 1964). The term infinite slope is used to designate a uniform slope of an extent
large enough that a typical element can be considered representative of the slope as a wholeand irregularities at the toe and the crest of the slide can be ignored. The soil properties andporewater pressure at any given distance below the ground surface are assumed constant. The
analysis is simple and direct.

Shallow Failure
Deep Failure
Figure 2.23: Variety of Slope Failure Circles Analysed at Varying Radii from a Single circle Center(Connolly, 1997)

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Figure 2.24: Graph Showing Factor of safety against Radius (Connolly, 1997)

Figure 2.25: Failure Surface Analyzed from a Variety of circle Centers (Connolly, 1997)

2.26: Slope Showing Overall Failure Surface and Smaller Individual ones (Connolly, 1997)62

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Figure 2.27: Analysing the Effect of External Water Load on a Slope (Connolly, 1997)

Figure 2.28: The Method of Slices (Connolly, 1997)

Figure 2.29: Fellenius Method (Connolly, 1997)

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Figure 2.30: Limiting Graphs for Values of f0 (Connolly, 1997)

Figure 2.31: Infinite Slope Analysis (Connolly, 1997)

2.15.7 Computer Based Slope Stability Analysis
The calculations involved in slope stability analysis are repitetive and laborious. Thus themost problems in practice are now solved with the aid of computers. Details vary fromprogram to program, but essentially the methods consist of reading the profile into thecomputer in the form of a series of straight lines and associated soil types, thensuperimposing on this profile a family of trial sliding surfaces which can be analysed to findthe lowest safety factor for the slope. A good program eill permit specification of an irregularslope with variable soil properties expressed eithr in total or effective- stress terms. It will
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accommodate external water, line and earthquake loads, and can accept porewater pressuresdescribed by either a constant soil parameter ru= /( H) or by a phreatic surface. It may also
permit selection of the method of solution (for example, by Bishops Method, Spencersmethod etc.), and of the shape of the slide surface, whether cicular or non-circular (Fredlund,1978).

The software XSTABL is such a program that provides an integrated environment for
performing slope stability analyses running MS-DOS. There are many factors such as slope
geometry and its surface conditions, roughness, weather and environmental conditions which
influence stability of a slope. Considering the fact that it would be impossible to relate thestability to all these factors within the time and scope of this study, deep circle and shallow
circle were considered for stability analyses using a computer code XSTABL.
Analytical Features of the Program XSTABLXSTABL is a fully integrated slope stability analysis program. The Generalized Limit
Equilibrium (GLE) method has been implemented in XSTABL. This method allows factorsof safety to be calculated for force and moment equilibrium or for force equilibrium only,
using different interslice force angle distributions. With this approach, the user can readily
calculate the factor of safety according to Spencer's, Morgenstern-Price, or one of themethods proposed by the Corps of Engineers. If an analysis requires a search for the mostcritical failure surface, the simplified Bishop and Janbu methods of analysis are selected dueto their relative ease of use. The program may be used to either search for the most criticalcircular, noncircular, or block-shaped surface, or alternatively, to analyze a single circular or
non-circular surface. The critical surface is identified by automatically generating andanalyzing failure surfaces between defined initiation/termination ranges or by connecting
points randomly located within search boxes specified by the user. This aproach minimizes
the required input parameters and can be effectively used to confine the surface generation
within a narrow, well-defined zone. The soil strength along the failure surface may bedescribed as either conventional (i.e., C, ø), undrained or non-linear Mohr Coulomb and canbe either isotropic or anisotropic. The undrained strengths are assigned as a function of thevertical effective stress.
XSTABL is programmed to handle:

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1. Heterogenous soil system
2. Anisotropic soil strength properties
3. Pore water pressure for effective stress analysis may be simulated by specifyinga) A Peizometric surfaceb) Multiple Phreatic surfacesc) Pore pressure gridd) Pore pressure parameter, Rue) Constant pore water pressure
4. Pseudo-static earthquake loading
5. Surcharge boundary loads.
6. Automatic generation and analysis of an unlimited number of circular, noncircularand block shaped failure surfaces.

Parameters Used in XSTABLXSTABL uses a soil unit number to uniquely identify the different soils in the slope. The
spatial distribution of the soils is then assigned by specifying the appropriate soil unit number
corresponding to the soil beneath each boundary segment The parameters for each soil unit
are assigned for isotropic and/or anisotropic soils using one of the options available underSOIL category.
A. Isotropic Soils
XSTABL can include soils that exhibit isotropic or anisotropic strength properties.
For each soil unit, the following properties are required:
1. Moist Unit Weight: Used to calculate the weight of each portion of the discretizedslice above the ground water level
2. Saturated Unit Weight: used to calculate the weight of each portion of thediscretized slice below the ground water level
3. C- Value: Represents the intercept on the Mohr-Coulomb envelop for the strengthparameters of the soil
4.

- Value: Represents the slope of the Mohr-Coulomb envelop for the strengthparameters of the soil

5. Ru Factor: Used to model the pore water pressures as a fraction of Ru of the total
vertical earth pressure within the slope.
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6. Constant Pore Pressure: This option allows the users to specify a constant porewater pressure for all points within a soil layer.
7. Water Surface Index: Defines a phreatic or piezometric surface that influences thesoil layer if a soil unit is not affected by a water surface, a water surface index of 0
(zero) should be specified in the soil property data table.
B. Anisotropic Soils
Soils anisotropic strength properties are described by assigning the Mohr-Coulomb
strength parameters (i.e. c and) to discrete angular ranges between -90° to +90°,

measured counterclockwise from the horizontal. Then, depending on the angle of thebase of each discretized slice, the appropriate c andvalues are selected from one of

the specified ranges for the computing the factor of safety.

Assumptions Used in XSTABL
Water surfaces, associated with soil units, may be used to represent phreatic or piezometricsurfaces for calculating pore water pressure at points within the soil mass if a water surface is
not defined across the failure surface zone. In general the phreatic surface approach is more
realistic and will calculate a higher effective strength. However, if piezometers have been
installed, and pore water pressure data is available for a potential failure surface, thepiezometric surface approach should be used for the analysis.
A. Phreatic Surface: These represent the free ground water level within the slope. In mostslopes this groundwater level will be inclined, indicating ground water flow. Such
conditions require that the pore water pressure calculations account for the seepage
losses This requires the determination of the equipotential line passing through thecenter of the slice base. The equipotential line is assumed to be a vertical line. The
inclination o the phreatic surface and the magnitude of the vertical distance between
the phreatic surfaces is located above the ground surface, hydrostatic pressures are
assumed to act upon the ground surface boundary.
B. Piezometric Surface: This presents the actual pressure head relative to a surface
within the slopes. This relative surface, in two dimensions, will correspond to a line
such as a potential failure surface. This option should only be used to examine thestability of single surfaces, or for a back analysis of an actual slope failure. Pore127 67

March 2010pressures are calculated according to the vertical distance between the base of theslice and piezometric surface corresponding to the appropriate soil unit.

3.1 Data Collection
The goal of this study is to produce microzonation maps in GIS environment by incorporating
the hazard analyses results. GIS is considered to be the most valuable and powerful software
for spatial data compilation, integration, analysis and graphical and non-graphicalrepresentation. Thus an updated administrative boundary map of the study area is essential torepresent the outcomes of the research. For geotechnical data collection field and laboratory
investigations were used from the study of Imtiaz (2009).

3.2 Updated Administrative Boundary of Municipal Area
An important issue in developing a seismic microzonation map is the selection of an
appropriate geographical reference, or geo-code, which will generally be driven by theavailability of input data regarding soils conditions. Municipal areas are divided into wards
and wards are divided into Mahallahs. For this study, Municipal administrative boundary
incorporating locations of Wards was adopted as geographical reference (geo-code) for the
microzonation. Recently Coxs Bazar municipality has been expanded and the administrative
map has not been finalized yet. For this study the proposed map as of January 2009, wascollected from Municipal Office where total area is divided in to 9 wards. The map is shownin Figure 3.1. GPS values of different core sites of the study area were collected. The existing
municipal map was scanned and was converted into digital map. Thus GIS-based updated
administrative boundary has been developed for the study area.

3.3 Geotechnical Data

Necessary data such as subsoil reports and geology, topography etc, was collected fromdifferent relevant sources. A total of 26 borehole SPT data were used to study site
amplification as well as soil liquefaction potential characteristics of municipality area.
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Twelve borehole data were upto a depth of 15 metres and fourteen boreholes are upto 30
meters. The borings were drilled vertically using the wash boring technique and equipment
capable of pushing tube samplers by hydraulic pressure. SPT was carried out in each boringat nominal 1.5 m intervals and the N-values, i.e., number of blows count for each standard
penetration was counted. Table 3.1 presents locations of borehole data from different areas ofCoxs Bazar Municipal used for this study, where the first twelve locations are the primarysources and the rest are secondary source of Imtiaz, 2009. Figure 3.1(a) shows the borehole
locations. To obtain soil parameters such as grain size (soil type and D50) Grain Size Analyse
data were also used from Imtiaz, 2009. Sample SPT and Grain Size Distribution curves areshown in Figure 3.1 (b) and (c).

Table 3.1: Location of Borehole Data of Coxs Bazar Municipal Area
Sl
No.

Location

Longitude

Latitude1

Cyclone Shelter near Diabetic Hospital

91.96212

21.44223

2

Baharchhara High School

91.96673

21.43847

3

Shaibal Hotel Water Tank

91.96683

21.43278

4

Golf Field Laboni Moore

91.97415

21.43012

5

Shamudra Bilash, Middle Saikat Para

91.98233

21.42287

6

Baharchhara Gol Chattar Field

91.97402

21.43463

7

Cox's Bazar Nursery

91.97487

21.43752

8

Cox's Bazar KG & Model High School

91.97060

21.44402

9

Fulbagh, Rice Market Road

91.98188

21.44445

10

Tekpara, Near Pond

91.98612

21.44283

11

Rumaliar Chhra, HSA Road

91.99183

21.44073

12

Bibekanondo Bidya Niketon, Ghonarpara

91.97903

21.43757

13

76/A, Kalatoli 3

91.97925

21.42755

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70

14

Cox's Bazar Press Club

91.98680

21.47290

15

Central Govt. PS cum CS

91.99040

21.45380

16

Peskarpara Govt. PS cum CS

91.98630

21.45540

17

Kosturaghat Govt. PS

91.98350

21.45320

18

Kolatoli World Vision MCS

91.99240

21.41800

19

Baitus Sharaf Jameya Mosque, South Baharchhara

91.98050

21.43550

20

Bangladesh Red Crescent Society, Motel Road

91.97380

21.44230

21

Bangladesh Water Development Board

91.97720

21.43980

22

Tekpara Govt. PS

91.98730

21.44590

23

Ghonarpara, Near Kaderia Non Govt. PS

91.98360

21.43840

24

Mosjid Compound, Ice Factory Road

91.99240

21.44630

25

Ramkrisna Shebasram, Baiddorghona

91.98710

21.43980

26

Primary Education Officers' Compund

91.99250

21.44010

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Figure 3.1(a): Coxs Bazar Municipal Area Map Showing Soil Borehole Locations

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Figure 3.1(b): Sample SPT data sheet

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Figure 3.1(c): Sample Grain Size Distribution curves

Hill ranges and hillock mainly appear to the Northern part of the Coxs Bazar town.
Baillarpara, Ghonarpara, Baiddorghona, Pahartali, Light House Para, Bus Terminal, Saikat
Para, Kolatoli areas of the municipality are mainly consisted of these hillocks. These hills
range from 15 meters to 40 meters in height. From the surface elevation map produced by the
Geological Survey of Bangladesh (Alam et. al., 1990) it can be observed that the averageheight of this hilly range is 30 meters.

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Hilly regions of this area have been surveyed and location, height, slope and other relevant
data have been collected. The slopes of the hills range from 45 degree to almost 90 degrees.
All most all the hill ranges contain some eroded slopes with almost vertical positioning.
Photographs of some of the prominent hills have been presented in Appendix D. Dense
population, houses and even multistoried buildings have been observed on these eroded
slopes and at their vicinity.

Eleven disturbed samples from different locations (photographs are provided in Appendix E)of the municipal area were collected for laboratory investigations including specific gravity
test, grain size analysis, Atterberg limits, standard compaction test and direct shear test. Table
3.2 and Figure 3.2 show the locations of the samples.
Table 3.2: Sample locations for estimation of landslide potential
Sl
No.

Location

Longitude

Latitude1

Hill behind PTI School

91.98433

21.43933

2

Ghonarpara (Boiddorghona)

91.98280

21.43807

3Light House Hill

91.97863

21.43055

4

Kolatoli Bipass

91.98728

21.41703

5

Boiddorghona (Behind Mediplus Pharmacy)

91.98290

21.43765

6

Kolatoli Sykat Para

91.98367

21.42183

7

Bus Terminal

91.99640

21.43642

8

Khaja Monjil, Pahartoli

91.98292

21.43498

9Circuit House

91.97613

21.43650

10

Ghonerpara Road(M r. Subratas House)

91.98102

21.43665

11

Boillarpara Temple Hill

91.98950

21.43533

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Figure 3.2: Soil sample locations for estimation of landslide potential

4.1 Seismic Hazard Analysis
It is well understood that earthquake damage to life and property results primarily fromstrong-ground shaking and indirect shaking-induced hazards such as liquefaction, landslide
etc. Severe earthquakes of the last decade in Armenia, China, India, Indonesia, Mexico,
Taiwan, Tehran, Turkey and the United States have reemphasized the importance of local
geologic site conditions in estimating the regional damage and consequent losses due tofuture major earthquakes. Again during land use management, city planning, engineering
design and in similar applications, proper evaluation of earthquake hazard is needed. The firststep in reducing the risk of the society from earthquake hazard is the assessment of the hazard
itself. Seismic microzonation map for strong-ground shaking, liquefaction, and landslide canplay a significant role in mitigating the effects of earthquake in urbanized regions.
9075March 2010

Seismic hazard analysis involves the quantitative estimation of ground shaking hazards at aparticular area. Seismic hazards can be analyzed deterministically as and when a particular
earthquake scenario is assumed, or probabilistically, in which uncertainties in earthquake size,
location, and time of occurrence are explicitly considered (Kramer, 1996). A critical part ofseismic hazard analysis is the determination of Peak Ground Acceleration (PGA) for an
area/site.

In this study, seismic hazard is defined as the probability that an event is exceeded for a given
time interval and the frequency of occurrence of this event. Thus seismic risk analysis
determines the probability of occurrence of a given event or conversely, the identification of
the event for a given probability or risk for a given site or area. The event may be any
parameter (e.g., PGA, PGV, PGD, Intensity) which is deemed to be representative of theeffect which is to be studied. It is important to consider the parameters which will correlate
well with the effect to be considered. For analyzing liquefaction potential, it is necessary to
use PGA because it directly affects the lateral force imposed on soil. This expected lateralforce is then considered in determining the safety factor for a particular soil location.
4.2 Methodology
Numerous methods for earthquake hazard assessment in a given site are available today.
Lomnitz and Epstein (1966) employed the Poisson process for the occurrence of large
earthquakes which is still used. Cornell (1968) and Esteva (1968) derived the general basis
for the most complete analysis of the whole seismic hazard problem with the inclusion of the
propagation mechanism of the ground motion. Shah and Vagliente (1972) used the Markov
model of earthquake prediction in seismic hazard analysis. A methodology for seismic hazard
estimation based on historical earthquake occurrences is presented in detail in Tomatsu andKatayama (1988) and Molas and Yamazaki (1994). In Japan, the seismic risk method
proposed by Kawasumi (1951) is still popular while in the United States, the basic method
proposed by Cornell (1968) is often used.

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A methodology for seismic hazard estimation based on historical earthquake occurrences ispresented in detail below. The seismic hazard evaluation at a specified site depends upon thedefinition of the following four models:(a) Earthquake source model: It is based on geological evidence, Seismic sources are
identified and modelled as a point, line, area or dipping plane. In this study, a point
source model is used. Figure 4.1 shows different source models.
(b) Seismicity model: The seismicity of each of the modelled sources is first determined frompast data available. The recurrence relationship relating the size of the past events inseismicity
terms of Magnitude (M) and Peak Ground Acceleration (PGA) is derived, The seismicity
model used
is usuallytakentaken
as as
model
usedininMolas
MolasandandYamazaki(1994)
Yamazaki(1994)
is usuallylog(v)=a+b*Mlog(v)=a+b*Mlog(v) =a+b*log(y)log(v)=a+b*log(y)

(4.1)
(4.1)
(4.2)(4.2)

whereMisisthetheearthquake
earthquake
magnitude
y isthegroundpeak groundacceleration,
v iswhere Mmagnitude
and yandis thepeakacceleration,v is occurrence
occurrence rate per year and a and b are regression constants. These relations can berate per year and a and b are regression constants. These relations can be written as

written as

M=M=(-log(T)-a)/b( log(T) a)/b

(4.3)
(4.3)

log(y)=( log(T) a)/blog(y)=(-log(T)-a)/b

(4.4)
(4.4)

where T (=l/ ) is the return period in years. Thus, the above equations represent magnitude andwhere T (=l/v) is the return period in years. Thus, the above equations represent magnitude
the peakgroundacceleration
for a return
period periodof T years.
andthe peakgroundacceleration
for a returnof T years.

(c) Attenuation model of ground motion: This describes the transfer of ground motions from(c) Attenuation model of ground motion: This describes the transfer of ground motions from thethe source to a particular site as a function of magnitude, distance and soil conditions. Here,source to a particular site as a function of magnitude, distance and soil conditions. Here, the peak

the peak ground acceleration is used to characterize the ground motion; the attenuation

ground acceleration is used to characterize the ground motion; the attenuation law is in the form

law is in the form

log(y) = b1 + b2 (Ms) - b3 log (r) - b4 (r)(4.5)

where r2 = d2 + h2, r is the hypocentral distance (km), d is the epicentral distance (km),h is the focal depth and Ms is the surface-wave magnitude. The attenuation law is required
92
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to determine the peak ground acceleration at the site for different events and then to
determine the regression constants a and b for Equation (4.4)(d) Recurrence
forecastingmodel
Various statisticalmodelsmodels
have beentestednumerous
research(d)
Recurrence
forecastingmodel-Various
statisticalhavebeenintested
in numerous

researchhowever,papers; forhowever,
forpurposes,
practicalearthquakes
purposes, earthquakes
are toconsidered
be random
papers;practical
are considered
be randomtoevents,
andevents,andprocess
the Poissonprocess
is used,which implies
assumptionsof stability
andthe
Poissonis used, which
impliesassumptionsof stability
and independence
over time.
independence
over time.
Since
analysisdefines motions
the occurrence
groundSince
hazard analysis
definesthehazard
occurrenceof groundequal toofor
larger motions
than aequal to value,or largera specified
value, theis probability
exceedanceused.
Forbeaspecified
the thanprobabilityof exceedance
used. For aofPoissonprocessis thismay
Poisson process
this may be expressed as
expressed
asp= 1 exp( vt)
p=1-exp(-vt)

(4.6)
(4.6)

mean annual
annual occurrence
occurrence rate ofof events
events ofof particularparticular peak groundground acceleration
where v is the mean
acceleration
the
of of
thethepeak
groundacceleration
for aforgiven
b andbover aa given
giventime
timet.t.From
Fromequations
equations
thevaluevalue
peak
groundaccelerationa giventimetime
periodt can tbe
calculated
as:andperiodcanbe calculatedas:log(y) = log( ln(p/t) a)/blog(y)=log(-ln(p/t)-a)/b

(4.7)
(4.7)

From theof theprocess,process,the relation
probability
exceedance ofFromtheassumption
assumptionof Poisson
the Poissonthebetween
relationthe
between
theofprobability
and the return
periodof peakperiod
groundis given by T, is given by
exceedanceandthe returnofacceleration,
peak groundT,acceleration,
T=1/v= t/log(p)-t/log(p)T=1/v=

(4.8)
(4.8)

4.3 Earthquake Analysis
In the regional seismic loss estimation analysis it is needed to determine the bedrock motionin the region. The most common method involves the use of an empirical attenuation
relationship. These relationships express a given ground motion parameter in a region asfunction of the size and location of an earthquake event. Applying statistical regression
analyses to recorded data has developed numerous relationships in the past. Often these
relationships are developed with different functional forms and with different definitions ofground motion, magnitude, distance, and site conditions. Figure 4.2 shows the flowchart forearthquake hazard analysis at bedrock level and Figure 4.3 shows flow chart for PGA
estimation at ground surface.
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4.3.1 Selection of Earthquakes around the Site
To estimate the seismic hazard in any particular site within a region requires a selection ofearthquakes which affect significantly the value of the hazard output. However, there is nostrict rule for selecting the maximum epicentral distance to the site. A small area around thesite results in a smaller number of earthquakes to be considered and some events outside thezone considered may affect the hazard in the site. This, naturally, will decrease the data set
for regression. On the other hand, a too large area may include earthquakes which do notaffect the seismic hazard in the site and are thus useless. It has been observed (Sharfuddin,2001) for an epicentral distance of 200 km and beyond, the b-coefficient of the GutenbergRichter formula is relatively stable. The evaluation of seismic hazard at a site is carried out
only if the number of earthquakes in the area considered (200 km radius) is larger than 10 andthe surface-wave magnitude is equal to or greater than 4.0. In this study evaluation of seismicparameter has been carried out using the seismic data over an area having a 250 km radiusaround Coxs Bazar Municipal area (Appendix B, Figure 4.4).
4.3.2 Selection of Attenuation Law of Peak Ground Acceleration
In Bangladesh, no PGA based attenuation law exists. To get engineering bedrock level (depth of 30m) PGA, equations presented in Table 2.6 (chapter 2) were used. The historical earthquakes aroundthe study area and their magnitude, epicentral distance, focal depth and intensity were considered
to estimate PGA (%g) value in this study.

To select the most suitable attenuation law for predicting rock motions, the methodology
adopted in few previous studies were followed (Sabri 2001, Sharfuddin 2001). From thesestudies it is found that McGuire (1978) as well as Joyner and Boore (1981) equations follow
the PGA trend of most large earthquakes in and around Bangladesh. Since, McGuire equation
has already been used for Bangladesh for seismic hazard analysis (Sharfuddin, 2001) and due
to its simple form it was selected for further use. Table 4.1 shows the PGA values at bedrock
level from two attenuation laws for the most significant earthquakes around the study area.
The attenuation laws for rock used in this study, McGuire (1978) and Joyner and Boore(1981) are presented as Equations 4.9 and 4.10 respectively.
94
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March 2010

PGA =0.0306e0.89Mr-1.17(4.9)

PGA = 0.0955 e(.573M) d(-1)* e(-0.00587d), d= (r2+h2)0.5(4.10)

Where, M = Earthquake Magnitude, d = Epicentral Distance, r = Hypocentral Distance and h= DepthTable 4.1: PGA values (% of g) at bedrock level from different attenuation laws for different
scenario events
Attenuation

M = 7.8

M = 7.66

M = 7.9

M = 6.5

M = 6.24

Law(1664)(1858)(1912)(1955)(1959)

McGuire0.03300.02140.0266

0.05620.07800.00290.00110.00130.02600.0401(1978)
Joyner andBoore (1981)

4.3.3 Regression Analysis
Seismic parameter b was evaluated from G-R relationship (Gutenberg and Richter, 1944), a
method utilizing extreme, instrumented and complete catalogs. Linear regression was applied
to each site which is taken as the centre of an area of 250 km radius where past earthquakes
are likely to occur again. The hazard curves of Mean Annual Rate of Exceedance ( ) versus
Peak Ground Acceleration (PGA) and Mean Annual Rate of Exceedance ( ) versus
Earthquake Magnitude (M) were generated at the rock levels. Figure 4.5 and 4.6 show the
regression curves fitting for Coxs Bazar Municipal area. The hazard in terms of the rocklevel PGA values and probable earthquake magnitude corresponding to return periods of 200
years were quantified from equation 4.3 and 4.4 as, 0.18g and 8.26 consecutively. Since thelargest Magnitude earthquake around the 350-450 km radius of the study area is 7.9 andaround 250 km radius is 6.5, a cut-off Magnitude of 7.5 earthquake was considered as the
expected one in 200 years return period and thus used for further analyses.
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ICUS Report 48(a) Point(b) Line source(c) Different area sources
Figure 4.1: Different source models

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March 2010

Location of site

Data period (based oncompleteness)
Minimum Magnitude
Earthquake catalogue

Selection of suitable radius
Selection of earthquakes

Magnitude frequency
relationship

Map of epicenters

Estimation of a and b
parameters

Selection of groundmotion property to beanalyzed (PGA)

Expected magnitude fordifferent return period

PGA frequency
relationship

Estimation of a and b
parameter

Selection of suitableattenuation law

Expected PGA for
different return
periods

Expected return
period for a fixed

Figure 4.2: Schematic flow of PGA determination at bedrock

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   

PGA at Bedrock

Subsurface Amplification

PGA at Ground Surface
Figure 4.3: Flow chart for PGA determination at ground surface

Figure 4.4: Historical Earthquakes around Coxs Bazar Municipal
98
83March 2010       











2

PGA (cm/sec )Figure 4.5: PGA versus mean occurrence rate for Coxs Bazar Municipal







       









 

Figure 4.6: Magnitude versus mean occurrence rate for Coxs Bazar Municipal

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4.4 Local Site Effects

Seismic zonation maps for strong-ground shaking, liquefaction and landslide can play asignificant role in mitigating the effects of earthquakes. Geographic information system (GIS)
provides an ideal environment for compiling and integrating regional databases of spatial
geologic and geotechnical information for purposes of seismic zonation.

4.4.1 Site Amplification Analysis

For site amplification analysis, shear wave velocity for 26 borehole data up to a maximum
depth of 30m were calculated by using equation of Tamura and Yamazaki (2002) presented
in Table 2.7. This empirical relation combines both depth and SPT-N value with soil
conditions. A soil database of 26 boreholes was developed in MS-EXCEL. In this study, theengineering bedrock was assumed to be the layer at which the shear wave velocity (Vs)exceeds 400 m/s, which exist almost 30 m deep from the surface of the study area. The
calculations show that the shear wave velocities at bedrock level vary from 400 m/s to 500
m/s.
Vibration characteristics plotted as transfer functions at different points of the study area
were estimated by employing one dimensional wave propagation program SHAKE. The
computations were made in the frequency range 0 to 20 Hz at frequencies every 0.05 Hz
interval. The loss of energy of seismic waves in the soil layers was also considered. An
estimation of the fundamental frequency and the maximum value of the amplification wereobtained for each site from the transfer functions. Typical graphical representation of
frequency versus amplitude is shown in Figure 4.7. For estimating the site amplification andpredominant frequency from the two approaches were taken into consideration. To evaluate
the extreme and worst hazard condition first peak of the plot was considered assuming thatthe largest amplification of the soil will occur at the lowest natural frequency or its
fundamental frequency. The other approach involved the estimation of average horizontal
spectral amplification (AHSA). This was adopted to derive more precise quantitative
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relationship between surface geology and local amplification. In this case the average
amplification value was estimated in the 0.1-10.0 Hz frequency range (Shima, 1978) and thefrequency value corresponding to that average amplification factor were selected. Table 4.2
presents the site amplification factors and corresponding predominant frequencies estimatedat different locations of Coxs Bazar Municipal area.
The computed results from the site amplification potential analysis were exported to a GIS
environment for further processing and visualization. They were classified into different
classes according to the extent of amplification factors and ranges of frequencies. The results
were plotted on the Coxs Bazar municipal area map using spatial interpolation among theborehole locations and converting the vectorial point features into continuous raster map
through grid generation. Thus microzonation maps (Figure 4.8 to Figure 4.11) based on site
amplification (times) and fundamental frequencies (hz) were developed considering the two
conditions.

In this study, the intensity attenuation law (Equation 4.11) for proposed by Sabri (2001) was
also used to verify the surface PGA. These intensities were converted into PGAs byfollowing Trifunac and Brady (1975) equation 4.12. The maximum PGA obtained from thisrelationship for alluvial soil was 0.25g for M = 6.24 earthquake of 1959. This PGA wasfurther compared to the ground surface PGA obtained through imposing subsurface
amplification to the bedrock PGA from McGuire (1978) equation.
I = 8.378+1.283*M-0.0007483*r-4.9*log(r)(4.11)

log PGA = 0.014+0.3 * I(4.12)

where, I = Intensity of Earthquake
M = Magnitude of Earthquake andr = Hypocentral Distance101
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Table 4.2: Results of Amplification factor and corresponding predominant frequency at
different locations of Coxs Bazar Municipal Area

Sl
No.

Location

Frequency (Hz)Amplification

1st
Peak

AHSA

1st
Peak

AHSA

1

Diabetic Hospital Cyclone Shelter

5.3

3.8

2.0

1.7

2

Baharchhara High School

5.2

3.6

2.3

1.7

3

Shaibal Hotel Water Tank

5.2

3.4

2.2

1.6

4

Golf Field Laboni Moore

5.0

3.3

2.0

1.6

5

Shamudra Bilash, Middle Saikat Para

5.3

3.6

2.0

1.6

6

Baharchhara Gol Chattar Field

5.9

4.1

2.1

1.7

7

Cox's Bazar Nursery

6.1

4.1

2.0

1.6

8

Cox's Bazar KG & Model High School

5.5

3.7

2.2

1.6

9

Fulbagh, Rice Market Road

4.2

3.6

2.2

1.6

10

Tekpara, Near Pond

4.6

3.2

3.6

2.0

11

Rumaliar Chhra, HSA Road

7.1

5.1

2.9

2.2

12

Bibekanondo Bidya Niketon,
Ghonarpara

6.8

4.4

1.9

1.6

13

76/A, Kalatoli 3

5.9

4.2

2.2

1.7

14

Cox's bazar Press Club

5.6

4.0

2.6

1.9

15

Central Govt. PS cum CS

7.7

5.5

2.0

1.6

16

Peskarpara Govt. PS cum CS

8.0

5.2

2.8

2.1

17

Kosturaghat Govt. PS

7.7

5.2

2.2

1.7

18

Kolatoli World Vision MCS

8.1

5.4

2.2

1.7

19

Baitus Sharaf Jameya Mosque

7.9

4.7

1.9

1.5

20

Bangladesh Red Crescent Society

7.3

4.8

2.0

1.6

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21

Bangladesh Water Development
Board

7.2

4.8

1.9

1.6

22

Tekpara Govt. PS

5.7

4.1

3.2

2.1

23

Ghonarpara, Near Kaderia Non Govt.
PS

7.3

4.8

2.2

1.7

24

Mosjid Compound, Ice Factory Road

3.8

2.8

2.8

2.1

25

Ramkrisna Shebasram, Baiddorghona

5.3

3.3

2.4

1.6

26

Primary Education Officers' Compund

11.2

4.3

2.4

1.5




 


















 

 





















 area
Figure 4.7: Typical Plots of transfer functions for two different boreholes conducted at the study

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Figure 4.8: Microzonation map based on fundamental frequencies considering extreme condition

Figure 4.9: Microzonation map based on fundamental frequencies considering AHSA

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March 2010

Figure 4.10: Microzonation map based on maximum amplification considering extreme condition

Figure 4.11: Microzonation map based on maximum amplification considering AHSA

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4.4.2 Liquefaction
Analysis
4.4.2
Liquefaction
Analysis

From the site amplification study, the average amplification factor was found to

From the site amplification study, the average amplification factor was found to be 2.3 and 1.7

be
2.3 and for1.7extreme
respectively
for extreme
andTheaverageconditions.
The rocklevel
respectively
and average
conditions.
rock level
PGA for return
periodof 200years was
as 0.18g.
the surface
PGAs calculated
multiplying
the rock
PGA
for estimatedreturn periodof Thus200 years
was level
estimated
as 0.18g. byThus
the surface
level PGA
withcalculated
amplification
were 0.41
extremeand 0.31
g considering
level
PGAs
by factor
multiplying
theg atrocklevelcondition
PGA with
amplification

AHSA. These PGAs were used in liquefaction analyses for the two cases. Figure 4.12 shows

factor were 0.41 g at extreme condition and 0.31 g considering AHSA. Thesethe flow chart for liquefaction potential analysis for the study area. Since the largest earthquake

PGAs
were
liquefaction
forMagnitude
the two cases.
4.12 shows
magnitude
hasusedbeen inconsidered
as 7.5,analyses
the relevant
Scaling Figure
Factor (MSF),
as shown

theflow2.8,chart
for liquefaction
potential
analysisthe study
thein Table
was selected
as 1.0. Particle
diameterdata for afor
particulardeptharea.
of soilSince
was obtained
from grainearthquake
size distribution
curves which
to find out thefrom curves
largestmagnitude
has were
beenusedconsidered
as CRR
7.5, values
the relevant(Figure 2.24). Borehole data from 26 points in Cox.s Bazar municipal area were stored in MS

Magnitude Scaling Factor (MSF), as shown in Table 2.8, was selected as 1.0.

Excel Worksheets. All the boring data include SPT N-values measured at 1.5 m interval. To

Particle diameter data for a particular depth of soil was obtained from grain size

consider the worst condition ground water table have been assumed at a depth of 1.5 m. The

distribution
curves factor,
whichFLwereusedto mfindout andthetheCRR
valuesfrom curves, for thetop 20of soil,resultingliquefaction
potential,liquefaction resistance

26 sitesBorehole
were calculated.
The 26flow
chart inof Coxsliquefaction
analysisused inthiswere
study isIL for the2.24).
(Figuredata frompointsBazar
municipal
area
shown ininFigureof Liquefaction
was data
providedin a tabulated
in TableWorksheets.
All potential
the boring
includeSPT N-form
valuesstoredMS 4.12.
ExcelResult

4.3. The computed results (Table 4.3) from the liquefaction potential analysis were exported

measured at 1.5 m interval. To consider the worst condition ground water table

to a GIS environment and plotted on the Cox's Bazar district map dividing the study area into

have
been assumed at a depth of 1.5 m. The liquefaction resistance factor, F ,different zones according to the ranges of liquefaction potential index values (Table 2.8). LThus

the 26haveforthe top 20
m wereof soil,and thepotential,
IL for whichmicrozonation
maps
developed
for resulting
liquefactionliquefaction
potential for thetwo conditions
been shownas Figure 4.13The
andflow
Figurechart
4.14.ofMicrozonation
were also
based onsites
were calculated.
liquefactionmaps
analysis
useddevelopedin this study
the surface PGA (Figure 4.15 and Figure 4.16) expected to be experienced by the area based on
isshown in Figure 4.12. Result of Liquefaction potential was provided in a
the surface PGAs calculated for different sites.

tabulated form in Table 4.3. The computed results (Table 4.3) from theliquefaction potential analysis were exported to a GIS environment and plottedon the Coxs Bazar district map dividing the study area into different zones
according to the ranges of liquefaction potential index values (Table 2.8). Thus
microzonation maps were developed for liquefaction potential for the two
conditions which have been shown as Figure 4.13 and Figure 4.14.
Microzonation maps were also developed based on the surface PGA (Figure

10691March 2010

4.15 and Figure 4.16) expected to be experienced by the area based on thesurface PGAs calculated for different sites.

Table 4.3: Liquefaction Potential Indices for different Locations of Coxs Bazar Municipal area
Sl
No.

Location

Liquefacion(Extreme)

Liquefacion(Average)

1

Diabetic Hospital Cyclone Shelter

43

high

20

high

2

Baharchhara High School

102

high

38

high

3

Shaibal Hotel Water Tank

141

high

74

high

4

Golf Field Laboni Moore

43

high

9

moderate

5

Shamudra Bilash, Middle Saikat Para

89

high

37

high

6

Baharchhara Gol Chattar Field

82

high

54

high

7

Cox's Bazar Nursery

25

high

8

moderate

8

Cox's Bazar KG & Model High School

81

high

35

high

9

Fulbagh, Rice Market Road

0

No

0

No

10

Tekpara, Near Pond

0

No

0

No

11

Rumaliar Chhra, HSA Road

0

No

0

No

12

Bibekanondo Bidya Niketon, Ghonarpara

0

No

0

No

13

76/A, Kalatoli 3

52

high

29

high

14

Cox's bazar Press Club

56

high

37

high

15

Central Govt. PS cum CS

4

low

1

low

16

Peskarpara Govt. PS cum CS

31

high

30

high

17

Kosturaghat Govt. PS

16

high

12

moderate

18

Kolatoli World Vision MCS

27

high

11

moderate

19

Baitus Sharaf Jameya Mosque

5

low

0

No

20

Bangladesh Red Crescent Society

4

low

1

low

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Sl
No.

Location

Liquefacion(Extreme)

Liquefacion(Average)

21

Bangladesh Water Development Board

3

low

0

No

22

Tekpara Govt. PS

0

No

0

No

23

Ghonarpara, Near Kaderia Non Govt. PS

41

high

29

high

24

Mosjid Compound, Ice Factory Road

128

high

100

high

25

Ramkrisna Shebasram, Baiddorghona

115

high

94

high

26

Primary Education Officers' Compund

20

high

13

moderate

Soil Properties

PGA at Surface

Groundwater Level

FL Method (Seed-Idriss, 1983)
Analysis of Liquefaction
Resistance Factor for Each
Layer (FL value)

IL Method (Iwasaki et. al.,1986)

Estimation of Liquefaction
Potential for each site
(IL value)
Figure 4.12: Flow chart of Liquefaction Analysis of the study area

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March 2010

Figure 4.13: Microzonation map based on liquefaction potential considering extreme condition

Figure 4.14: Microzonation map based on liquefaction potential considering AHSA

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Figure 4.15: Map showing regional distribution of surface PGA considering extreme condition

Figure 4.16: Map showing regional distribution of surface PGA considering AHSA

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March 2010

4.4.3 Landslide Potential Analysis
The overall stability failure mechanism is development of slip circles resulting in a deep
sliding surface. This is a conventional soil mechanics stability problem. Pre-existing slip
planes within the soil, cracker material can have a significant effect on slope stability.
Stability analysis is carried out to evaluate the factor of safety against bearing capacity failure.
The program used for stability analysis is XSTABL, which is a fully integrated slope stability
analysis program. XSTABL performs two dimensional limit equilibrium and analysis toevaluate the factor of safety for a layered slope using the simplified Bishop Method. The
strength parameters of the slope and foundation materials required for the analyses could beobtained from consolidated undrained direct shear tests performed on soil samples. The
minimum values of undrained cohesion (cu) and undrained angle of internal friction ( u) wereused in the slope stability analyses. The values of cu andu used in all the analyses have been

provided in Appendix I. The location of the water table in all the slope sections was assumed
to be well below the toe of the slopes. The height of the slope was considered as 30 m (100ft) which was observed from field survey as the average height of the hills of Coxs Bazar.
Generally the slopes were found to be 60° to 80°. Considering human activities and ongoinghill cutting activities the average slope of the hills were assumed to be 70°. From the analyses
it was observed that only single data contained the representative value of satisfactory
Factor of Safety (Table 2.10) and the rest were unsafe. Thus the landslide potential wascategorized as high and low for Factor of Safety being greater than or equal to 1.2 and lessthan 1.2 consecutively. The corresponding Factor of Safety values have been exported to GIS
and plotted on the Coxs Bazar municipality range. Thus the microzonation map based onlandslide potential was developed which is shown as Figure 4.17.

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Table 4.4: Summary of Landslide Potential Analysis

Sl No.

SampleFactor of
Safety1

Hill behind P.T.I High School

1.44

2

Ghonarpara Hill

0.31

3

Light house Hill

0.69

4

Kolatoli Bypass Hill

0.68

5

Boiddorghona Hill

0.30

6

Kolatoli Saikat Para

0.58

7

Bus Terminal Hill

0.72

8

Khaja Monjil, Pahartoli

0.33

9

Circuit House Hill

0.60

10

Ghonerpara Road (M r. Subratas House)

0.30

11

Boillarpara Temple Hill

0.31

112
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March 2010   

 

 

 

 



 

 

 
 

 

 

 
       Figure 4.17: Microzonation map based on landslide potential in Coxs Bazar Municipal area

4.5 Seismic Hazard Integration

The most important endeavor of this study is the estimation of seismic hazards linked withthe local site attributes of soil amplification, liquefaction, and landslide and then integratingthem in such a manner so that a reflection of probable actual disaster consequences can be
represented. It is not feasible to resolve how much of the potential hazard is discretely
attributed by each local site effect, consequently the ultimate regional seismic hazard
distribution is established on a weighted average combination of the hazards related witheach effect.

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4.5.1 Integration of Site Effects in the GIS Environment

Since every analysis region is different; the quantification of the secondary site effects andthe weighting scheme for combining the various seismic hazards is considered to be heuristic,
based on judgment and expert opinion about the influence of local site conditions in theregion and the accuracy of the available geologic and geotechnical information. Figure 4.18
shows the flow chart for developing combined seismic hazard maps.
The rock level ground shaking in the region was determined as 0.18g. This PGA wasconsidered as constant since the study area is small. The seismic intensity is basically asubjective one, based on the human sensations or damage during an earthquake. It was
assumed that the final combined seismic hazard would be quantified in terms of Modified
Mercalli Intensity (MMI) (Appendix K). The equation used here to convert PGA to intensity
is developed by Trifunac and Brady (1975) and is given by Equation 4.12.

For the extreme condition the regional distribution of ground shaking hazards (MMIGS)
considering 2.0, 2.5 and 3.0 times amplification of the PGA were calculated and presented as
Figure 4.19. The MMI scale is subjective and assigned as integer values, therefore the MMI GS
values are rounded to the nearest 0.5
Figure 4.13 shows the regional distribution of liquefaction potential in the study area
categorized as high and low. Figure 4.17 shows the qualitative description of landslide
hazard in the region. For simplicity, areas were designated as having high and low
landslide potential. The following heuristic rules are used to quantify the seismic hazards due
to liquefaction and landslide:
MMILIQ / MMILAN= MMIGS +2 (For region designated as high)MMILIQ / MMILAN= MMIGS +1 (For region designated as moderate) and otherwise

MMILIQ / MMILAN=0

The rules for combining the various hazards are based on expert opinion (after Stephanie andKiremidjian, 1994) about the relative accuracy of the hazard information and the behavior of
114
99March 2010

the local geology. For this study, it is assumed that the ground-shaking hazard is the mostaccurate followed by liquefaction and landslide.
For this study, the possible combinations and their assumed weights are shown in Table 4.5.
The final combined hazard (MMIF) is computed as a weighted sum of the various hazards.
The weights in each rule must sum to 1.0. The additive factor in rules in Table 4.5 is toaccount for the increase in hazard due to two or more hazards occurring. Table 4.6
summarizes the results of the calculations for combined hazard analysis which are presented
by Figure 4.20.
Following the similar procedure calculations were performed for combined hazard analysis
considering the approach based on average horizontal spectral amplification (AHSA). The
results are shown in Table 4.7. The regional distribution of combined hazards for thiscondition is presented in Figure 4.21.
Figure 4.22 and 4.23 show the regional distribution of the final combined seismic hazard(MMIF) for extreme condition and considering AHSA.
Table: 4.5: Quantification rules for seismic hazard (Stephanie and Kiremidjian, 1994)
Rule

Possible hazards

Weighting Scheme for Final combined
Hazard (MMIF)(a)Ground shaking

MMIF=MMIGS(b)Ground shaking + Liquefaction

MMIF= .55 MMIGS + .45MMILIQ+. 5(c)Ground shaking+ Landslide

MMIF=. 65 MMIGS + .35MMILAN+. 5

1. MMIF= Final Combined Hazard
2. MMIGS= Ground Shaking Hazard
3. MMILIQ=Liquefaction Hazard
4. MMILAN=Landslide Hazard
5. MMIF must be less than or equal 12

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BNUS Annual Report-2009

ICUS Report 48

Table
Table
4.6:
4.6:Combination
Combination
ofof
possiblepossiblehazards
hazards
forfor
Coxs
Coxs
Bazar
Bazar
Municipal
Municipal
Area
Area
considering
considering
extremeextremecondition
condition
due
due
toto
a scenario
a scenario
event
event
equivalentequivalent
toto
M=
M=
7.57.5
Earthquake
Earthquake

PossibleGround
GroundShaking
Hazards
Possible
Shaking
Hazards

Possible
Possible
Hazards
Hazards

Area
Intensity Area
Intensity

Area
Area

(sq
km)
km) (%)
(%)
(MMI
(MMI
F) F) (sq2.02.0times
times
Amplification
Amplification

VIII
VIII

3.20
3.20

47.26
47.26

2.52.5times
times
Amplification
Amplification

IXIX

2.87
2.87

42.36
42.36

3.03.0times
times
Amplification
Amplification

IXIX

0.70
0.70

10.38
10.38

Intensity
Intensity Area
Area

Area
Area

Combination
Combination
ofof
Possible
Possible
Hazards
Hazards

(MMI
(MMI
(sq
km)
km) (%)(%)F) F) (sq2.02.0times
times
Amplification
Amplification
++
High
High
Liquefaction
Liquefaction

XX

2.95
2.95

43.62
43.62

2.52.5times
times
Amplification
Amplification
++
High
High
Liquefaction
Liquefaction

XX

2.40
2.40

35.50
35.50

times
times
Amplification
Amplification
++
High
High
Liquefaction
Liquefaction
GroundGroundShaking
Shaking 3.03.0

XX

0.54
0.54

7.96
7.96

++
Liquefaction
Liquefaction

2.02.0times
times
Amplification
Amplification
++
Low
Low
Liquefaction
Liquefaction

VIII
VIII

0.13
0.13

1.95
1.95

2.52.5times
times
Amplification
Amplification
++
Low
Low
Liquefaction
Liquefaction

IXIX

0.06
0.06

0.93
0.93

3.03.0times
times
Amplification
Amplification
++
Low
Low
Liquefaction
Liquefaction

IXIX

0.19
0.19

2.75
2.75

times
times
Amplification
Amplification
++
High
High
Landslide
Landslide
GroundGroundShaking
Shaking 2.02.0

XX

0.11
0.11

1.65
1.65

++
Landslide
Landslide2.52.5times
times
Amplification
Amplification
++
High
High
Landslide
Landslide

XX

0.42
0.42

6.25
6.25

2.52.5times
times
Amplification
Amplification
++
Low
Low
Landslide
Landslide

IXIX

0.02
0.02

0.23
0.23

116
116
101

March 2010

Table 4.7: Combination of possible hazards for Coxs Bazar Municipal Area considering
AHSA due to a scenario event equivalent to M= 7.5 Earthquake

Intensity

Area

Area

(MMIF)(sq km)(%)

1.7 times Amplification

VIII

6.01

88.81

2.0 times Amplification

VIII

0.76

11.19

Intensity

Area

Area

(MMIF)(sq km)(%)

1.7 times Amplification + High Liquefaction

X

3.51

51.79

2.0 times Amplification + High Liquefaction

X

0.43

6.30

IX

1.27

18.81

IX

0.06

0.83

1.7 times Amplification + Low Liquefaction

VIII

0.64

9.41

2.0 times Amplification + Low Liquefaction

VIII

0.25

3.63

1.7 times Amplification + High Landslide

IX

0.53

7.78

1.7 times Amplification + Low Landslide

VIII

0.02

0.24

Possible Ground Shaking Hazards

Possible Hazards

Combination of Possible Hazards

1.7 times Amplification + Moderate
Ground Shaking+ Liquefaction

Liquefaction
2.0 times Amplification + Moderate
Liquefaction

Ground Shaking+ Landslide

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BNUS Annual Report-2009

ICUS Report 48

103

March 2010

Site Amplification

Liquefaction Potential

Landslide Potential

Heuristic Combination Rules

Combined Seismic Microzonation Map

Figure 4.18: Flow chart for Combined Seismic Hazard Map

3 times Amplification
2.5 times Amplification

2 times Amplification

Figure 4.19: Map showing the possible Ground Shaking Hazards for extreme conditions over the area

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ICUS Report 48

3 times Amplification

2.5 times Amplification+ High Landslide

2.5 times Amplification

2.5 times Amplification+ Low Landslide

2 times Amplification

2 times Amplification+ High Landslide

3 times Amplification+ High Liquefaction

3 times Amplification+ Low Liquefaction

2.5 times Amplification+ High Liquefaction

2.5 times Amplification+ Low Liquefaction

2 times Amplification+ High Liquefaction

2 times Amplification+ Low Liquefaction   

 

 

 

 



 

 

 
 

 

 

        Figure 4.20: Map showing the possible hazard combinations for extreme condition

120105

March 2010

Figure 4.21: Map showing the possible hazard combinations considering AHSA

106

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ICUS Report 48
      Figure 4.22: Map showing the regional distribution of combined seismic hazard (MMIF) in Coxs Bazar
Municipal Area for extreme condition

Figure 4.23: Map showing the regional distribution of combined seismic hazard (MMIF) in Coxs Bazar
Municipal Area considering AHSA

122107

March 2010

5.1 Conclusions

In this study, GIS has been used to develop seismic microzonation maps for the study area
where primary hazards due to ground shaking and local site effects such as soil amplification,liquefaction and landslide have been considered. Prior to that, different field and laboratory
test data collected at different depths from 26 sites and laboratory tests of soils collected from
11 hills of the study area have been performed for geotechnical characterization. Furthermore,this study introduces a methodology to combine the different hazards based on a weighted
average approach. In the GIS environment, maps representing regional geologic andgeographic information have been overlaid and their attributes were combined to produce
intermediate maps of regional seismic hazards. This is for the first time comprehensive
earthquake hazard estimation for Coxs Bazar Municipality has been carried out.

Due to an earthquake of Magnitude 7.5 with 200 years of return period around 250 km radiusof Coxs bazaar Municipal Area, the rock level PGA is estimated as 0.18g. The results of theanalyses for ground susceptibility can be interpreted for two different conditions.

Considering the extreme or most severe condition the rock level PGA can be amplify 2.3
times on an average in the alluvium and will gain a PGA of 0.41g in the surface. From thedeveloped microzonation maps, it can be observed that the Southeastern end of ward no. 5
will experience the highest frequencies. Ward no. 4 consisting of East Tekpara,
Rumaliarchhara and Tarabaniachhara might be affected by 3 times site amplification.
Liquefaction analysis for the study area reflects that it is susceptible to very high liquefaction
potential. From the borehole investigations and grain size distributions, it was observed thatthe soil up to 20 meter depth is mostly sandy having D50 ranging from 0.12 mm to 0.22 mm.
It was observed that the sandy silts with trace clay, layer of silt and sand, silty sand having
greater particle diameters and low to medium SPT N-values showed higher liquefaction
potentials.

According to the study, the landslide potential of this area is very high.

Approximately 8.13% area under the municipality is hilly. The hills located in Ghonerpara,
Boiddorghona, Pahartoli and Boillarpara are found to be very unstable. The combined hazard
analysis shows that if the area experiences both ground shaking and liquefaction during a
scenario earthquake having a magnitude of 7.5, the area can be severely affected and the108

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intensity due to the combined effect of the hazards can be as high as X in MMI scale. The
town will be highly endangered (44% area is affected) if high liquefaction associates withamplification factor as low as 2 times. On the other hand if 2.5 to 3 times site amplification
occurs, still there is a high risk (MMI = IX) even in case of low liquefaction occurrence. The
hilly region is highly susceptible to slope instability, moreover, 77% of the hilly region is on
the risk of experiencing very high intensity (MMI = X), if 2.5 times amplification of groundshaking occurs.

Considering the average horizontal spectral acceleration (AHSA), the results are obtained fora moderate hazard condition. The average frequency expected to be experienced by the area
is calculated as 1.7 and thus the surface PGA is obtained as 0.31g. Approximately 89% of thearea can be affected if 1.7 times amplification of the ground shaking occurs and 11% area
might be affected by 2.0 times amplification. If high liquefaction associates with roundshaking amplified by of these two amplification factors the area can be affected by a
combined hazard intensity of X. Similarly moderate liquefaction associates with these groundshaking hazards can cause combined hazard of intensity IX. More than 50% area can beaffected if high liquefaction combines with only 1.7 times amplification of ground shaking.
The entire hilly region is liable to only 1.7 times amplification. Approximately 96% of thehilly region (8% of the total area) might experience a combined intensity of IX if highlandslide associates with only 1.7 times amplification of ground shaking.

The developed maps can act as a guide for the authorities at the national and regional levels
in land use management, revision and enforcement of appropriate building codes andformulation of plans for mitigating measures against earthquake risk affecting the region
considered.
5.2 Scope for Future Study

The study is covered with extremely wide-ranging subject; consequently several field offuture study can be recognized for instance:

124109

March 2010i.

For Bangladesh, no PGA attenuation law has been developed, due to shortage of strong
motion data. PGA attenuation relationships predicting strong ground motions in terms ofmagnitudes, distance, site geology, and other factors, using various models and data setsshould be developed for the country.

ii.

Study of regional tectonics with particular emphasis to locate active faults and fault planesolutions is strongly recommended. This can lead to more accurate estimation of
hazardous conditions.

iii.

In this study, SPT-N values were converted into shear-wave velocities using empiricalcorrelation. Shear-wave velocities are needed to be directly estimated for different soils
using cross-hole, down-hole or blasting techniques. Then correlation should be developed
for the SPT-N values of local soils with shear-wave velocities.

iv.

Grain Size Analysis specially, the mean particle diameter, D50 and fine contents areimportant data for every 1 meter depth for proper liquefaction analysis.

v.

Based on soil (natural) frequency, some zones can be suggested for building height
restrictions using thumb rules.

vi.

Based on liquefaction potential index zones can be suggested where ground improvement
is necessary.

vii.

Vulnerability of landslide depends on location, land use, land cover, rainfall as well as
weather, geological structure and type of human activities. These factors should be taken
into consideration during landslide potential analysis.

viii.

A very simplified process for integration of various sites attributes has been used in thisstudy. Improvements are needed in the models together with the quantification of thehazards and heuristic weighted average approach. The analysis and modeling capabilitiesof the GIS provide an ideal environment to conduct sensitivity studies that will help torefine different hazard combination schemes.

ix.

Further study can be taken by performing analysis of site amplification and calculation oftransfer functions considering real earthquake strong ground motion data as input in
SHAKE.

110

BNUS Annual Report-2009125PART-II
Earthquake Vulnerability Assessment at Old Dhaka(Ward No.68)

Prepared By
Israt Jahan
Sharmin Ara
Mehedi Ahmed Ansary

BANGLADESH NETWORK OFFICE FOR URBAN SAFETY(BNUS), BUET, DHAKA

126

ICUS Report 48

1. INTRODUCTION
Bangladesh, one of the most disaster prone countries in the world deserves disastermanagement as the key issue for overall development of the country. The risk in urban centeris compounded due to unplanned urbanization and development in high risk zones. Althoughmost of the major earthquakes in recent days have occurred away from major cities and have
only affected relatively less populated areas, significant earthquake hazard exists for the cities
due to its heavy unplanned built environment and high density of ever increasing population.
The 1897 Great Indian Earthquake which originated at an epicentral distance of only 230 km
from Dhaka caused extensive damage on brick masonry structures in Dhaka (Oldham, 1899).
Dhaka is vulnerable to earthquake due to high population density, unplanned structures, andlack of awareness and preparedness at community level, etc. Dhaka as the capital of
Bangladesh accommodates a large estimated population of 12.8 million in the wider
metropolitan area while the city population stands approximately at 7.0 million as of 2008
(BBS, 2009). Old Dhaka is more vulnerable to earthquake due to its relatively high density of
population. The projected density of population in Kotwali Thana, a major part of Old Dhaka
is 1, 61,198 per square kilometer in 2009 (BBS, 2001). Besides, the densely built fabricconsisting of vulnerable aged and unreinforced masonry buildings along with narrow local
streets makes the locality more susceptible to earthquake. Once a great earthquake occurs,
Dhaka may suffer immense loss of life and property due to unplanned development. This will
have severe long term repercussion for the entire country.
Earthquake as a disastrous event needs to be addressed in a more precise way. Earthquake
social vulnerability assessment of an area put a remarkable importance in proposing aneffective evacuation plan considering the prevailing local condition to reduce loss. While
natural hazards will continue to occur, their capacity to become a disaster or merely amanageable event depends on many factors, including the magnitude of the hazard, thevulnerability of people and their communities and the built environment. People are the major
concern in any disaster risk mitigation and people at the disaster prone areas are mostvulnerable. To make an effective plan in disaster risk reduction, the major goal should be theassessment of existing social vulnerability and propose initiatives to raise awareness level ofthe local community in reducing loss after effects.
As Old Dhaka is vulnerable to earthquake, BNUS is developing the earthquake evacuation
plan for Ward No.68 as part of this area. The site is characterized by high density of
127 111

March 2010

population living in a very compact land area with close proximity of buildings along anarrow local road. Sometimes it is become difficult to separate one building to another. The
condition is inconceivable what may happen with an attack of earthquake. In order to reduce
the loss due to an earthquake, BNUS has taken an effort to make an evacuation plan of thestudy area considering the existing situation.

2. METHODOLOGY
The major concern in any disaster risk mitigation measures falls on raising awareness level ofthe local community. A socio-economic survey of 210 households in Ward no. 68 of theolder part of Dhaka City is conducted for the assessment of social vulnerability. The sample
size was chosen on random basis at 95% confidence level which is 2% of total projectedhousehold 10,942 in 2009(BBS, 2001) in the study area. The social vulnerability of
individuals due to an earthquake is assessed within the households. The social vulnerability
indicators and relevant data have been selected from the literature. Information regarding thelevel of public awareness about earthquake risk of the community is found through thissurvey. In this study building vulnerability is also assessed by using two method, Rapid
Visual Screening (RVS) method and Turkish Level-I and Level-II Method. For RVS method1383 buildings (residential and public building) were assessed which cover more than 90
percent of the total existing buildings in the study area. Turkish Level-I and Level-II, a moredetail analysis of the building is used to assess, which are proposed to be used as evacuation
shelter. Around twenty seven public buildings as well as common places are selected forevacuation place. Among them only the Reinforced Concrete buildings are assessed by
Turkish method, includes religious place like mosques, community center, educational
institutes like schools, colleges and other public places along with the open spaces like park,
playground etc. are considered as evacuation site. For structured and organized analysis, thecollected data has been compiled and analyzed to understand the earthquake vulnerability ofthe study area. This portrays a clear view of the whole community.

3. STUDY AREA AT A GLANCE
The study area, Ward no. 68 is located on the northern bank of river Buriganga being a partof Old Dhaka. The area covered by the study ward is 1.5 sq. km and accommodates
approximately 1.5 lacs population. Among these large number of population, 18362 are adult.
It is under the jurisdiction of Bangshal Thana and part of Kotwali Thana. The ward is112

BNUS Annual Report-2009
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ICUS Report 48

surrounded by five wards of DCC in three sides and the river Buriganga at the south. In north
there lies ward no. 66, to the west ward no. 67 and to the east lies three ward  ward no 71, 72
and 73. In this area sixteen educational institutions are found including govt. primary school,
high school, madrasha and Girls College etc. In the study area seven health care centers isplaced and on the west Sir Salimullah Medical College and Hospital is situated which is oneof the reputed and renowned places within Old Dhaka. Old Dhaka is well-known for mosque
and in the study ward 13 mosques are found with different architectural design. There is also
some DCC approved service center found like community center, gymnasium, public libraryand play ground. Ward no. 68 is confined by Haji Abdur Rashid Lane and French Road at theeast; Sharatchandra Chakrabarti Road at the west; Bangshal Road at the north and Badamtaliat the south (see MAP- 1).



N



























































Study Area




























































  


















  











 
     
 





 

Map-1: Location Map of Study Area

129 113

March 2010

Photo1: Old and Aged Building

Photo 2: Congested Residential Building

Photo 3: Narrow Local Road

Photo 4: Ahmed Bawani School and College

Photo 5: Babubazar Ghat Jame Mosque

114

Photo 6: Shajadi Begum Jame Mosque

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ICUS Report 48

4. SOCIAL VULNERABILITY ASSESSMENT
The surveyed 210 households having total family members of 1092 has the average family
size five. It is found from the survey that 21% of the surveyed household members age groupvaries between 0-14 years and over 59 years represents only 6% of the household members.
Among the total family members 42% are female. In any disaster female, kids and aged
members are considered more vulnerable than others. In Bangladesh usually the person who
can sign his name is considered as literate. With respect to this criterion in the study area only
7% members are illiterate. If the overall situation is considered regarding what have to bedone during and after an earthquake strikes, people of the area is almost unfamiliar with it.
With respect to these criteria the area could be said to be vulnerable to earthquake hazard insocial context.
4.1 EARTHQUAKE AWARENESS OF THE HOUSEHOLD MEMBERS
A percentile configuration of 75% members of the surveyed households shows theirperception of being aware about earthquake. Table-1 shows the awareness level of thehousehold members in the study area. It is a good indication that 94 households among the
210 contain 100% awareness level i.e. all of their family members are aware about
earthquake while only 4 families are unaware about the risk.
Table-1: Earthquake Awareness Level of the Household Members
Percentage
Householdof theNumberHousehold
Aware Unaware
members
1-19%
20-29%
30-49%
50%

4
8
15
16

13
34
22
16

Percentage
Householdof theNumberHousehold
Aware Unaware
members
51-69%
70-92%
100%

22
47
94

15
12
4

4.2 EARTHQUAKE AWARENESS OF THE HOUSEHOLD MEMBER ACCORDING TO AGE GROUP
AND EDUCATIONAL LEVEL

Figure-1 depicts that household members of the age group 15-29 years are more aware thanother age group. The members who are in the age group of 0-14 years, maximum are school
going and kids. Among the school going members, very few are aware about earthquake. As
131 115

March 2010a result, it is observed that the number of aware and unaware members is more or less equalin this group. A number of students especially who had primary to high school level
education, got a sort of awareness training related to earthquake preparedness in their school(see Figure-1 and 2). Most of the student studies in the local schools such as Armenitola Govt.
High School, Narinda Govt. Boys High School, Anondomoyee Girls High School, etc.
which prepared the students to confront earthquake danger (Jahan and Ansary, 2007). Thispreparedness involves class lectures on earthquake, its risk and effects on life, earthquake
drill and what should anyone do before, during and after an earthquake attack.

Figure-1: Earthquake Awareness of the Household Member according to Age Group

Figure-2: Earthquake Awareness of the Household Member according to Educational Level
4.3 COMPARISON BETWEEN AGE GROUP AND EDUCATIONAL LEVEL
From the study, it is found that almost 96% literate respondents have earthquake awareness.
Table-2 shows that the literacy rate is more in the age group 15-29 and 30-44 years and they
are more aware about earthquake than the people of other age groups. The age group 15-29
years is more aware about earthquake because most of them are student and 30-44 age groups
are basically engaged with different professions. Professional group keeps themselves up to116

BNUS Annual Report-2009132

ICUS Report 48

date with day to day information received through professional activities and so they havemore experience than others.
Table-2: Comparison between Age Group and Educational Level
Age

Educational Level

Group

Illiterate

Literate

Aware Unaware Aware Unaware
0-14

1

10

118

105

15-29

13

7

287

36

30-44

5

5

227

53

45-59

1

2

137

24

59+

11

18

20

12

4.4 EARTHQUAKE AWARENESS OF THE HOUSEHOLD HEAD
The household head (male or female) of the family plays a vital role in any decision making
and in Bangladesh mostly the male possess the position to be head of any family. So thestatus of the family head is also examined to find out the real condition of the family to copewith any disaster along with the families resilience. Figure-3 shows the earthquake
awareness level of each household head in comparison with their educational level andoccupation. It is clear from the figure that most of the household head are businessmen in the
study area and most of them are aware about earthquake.

Figure 3: Earthquake Awareness level of the Household Head133 117

March 2010

4.5 EARTHQUAKE KNOWLEDGE OF THE RESPONDENTThe field survey reveals that most of the respondents know what is an earthquake and 69% ofthem think earthquake as the shaking of land, rolling of earth surface. Among them maximum
respondents came to know about earthquake from newspaper and by watching television or
movie. Students acquire knowledge about earthquake from the lessons taught at schools.
Vulnerability of earthquake depends on the awareness of the community people. About 74%
respondents in the study area are aware about earthquake.
4.6 EARTHQUAKE EXPERIENCE OF THE RESPONDENT
It is found in the study area that about 70% respondents have experience of earthquake. Whenthe people experienced earthquake they take some immediate actions to protect themselvesfrom earthquake exposure. In Bangladesh, in most cases ground shaking occurs only for few
seconds though the average magnitude varies from 5.0 to 6.0 in Richter scale. From fieldsurvey, it is found that most of the respondents felt earthquake but it was over before taking
any actions. The next common response is to go out of home immediately which has reported
by more than 30% of the respondents. A number of respondents also mentioned about being
awakened from sleep when earthquake occurred at night (see Figure -4).

Figure-4: Instant Response of the Respondent when Felt Earthquake

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4.7 EARTHQUAKE VULNERABILITY OF THE COMMUNITY
In the study area most of the respondents (75%) think their community is exposed toearthquake vulnerability. The surveyed respondents considered a range of factors that caused
the area to be earthquake vulnerable. They gave response to identify the reasons behind
earthquake vulnerability according to raking or priority basis. From Figure-5, it is found thatmaximum respondents prioritize the fact that buildings in Old Dhaka are aged and damaged.
The next importance goes for weak construction with defective building

Figure-5: Reasons behind Earthquake Vulnerability to Community
design (pillar, column and foundation of building). Danger imposed from congested electric
wire in the area is also considered as a factor of earthquake vulnerability to the community.
The socio-economic condition of the study area indicates that the area is in between low andmiddle income group. It can be said that if a disaster attacks, most of them could not recover
the losses. The expected loss is unpredictable, financial help will be required from the outside
people, government and foreign agencies.
4.8 EARTHQUAKE VULNERABILITY OF THE RESIDING BUILDING
From field survey it is found that 44% respondents claimed their residing building isvulnerable, there are various factors behind the perception. From Figure-6, shows maximum
respondents think the residing buildings are old in the locality and it is the main reason.

135 119

March 2010

Another important factor recognized by the respondents for earthquake vulnerability is weakcolumn, beam and foundation of building. There are other important factors which are related
to earthquake vulnerability such as building construction without following RAJUK set backrules, congested and unplanned buildings in the locality, narrow stair cases, unplanned
narrow roads etc. It is also observed that 55% of the surveyed buildings staircase width is lessthan or equal to 3 feet that is not apt in terms of evacuation from the building.

Figure-6: Earthquake Vulnerability of the Residing Building

The earthquake vulnerability of the residing buildings is also assessed by Rapid Visual
Screening (RVS) Method. A total number of 1383 buildings have been analyzed forvulnerability assessment by this method. A RVS score 2 of a building is considered as cutoff score for the study area. The score below 2 for a structure is assumed to vulnerable andrequire further investigation. From building vulnerability assessment it has found that 53%

Figure-7: Buildings Classified on RVS Score

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buildings in this area are vulnerable and require detail evaluation and tenacious action for

ICUS Report 48

structural improvement (see Figure -7). Other wise all of these buildings should collapse if

an intense magnitude of earthquake strikes on the area.
buildings in this area are vulnerable and require detail evaluation and tenacious action for
4.9 structural
DISCUSSIONWITH FAMILYEMBERSCOMMUNITY
ARTHQUAKE
improvement(seeMFigure-7).AND
Other
wise all ofABOUT
these Ebuildings
should collapse if
an intense magnitude of earthquake strikes on the area.
People usually discuss with family members and community people about earthquake. Thereis disparity
in the frequency
of discussion
members
andEARTHQUAKE
community people.
4.9 DISCUSSIONWITH FAMILYMEMBERSamong
AND Cfamily
OMMUNITYABOUT
From Figure-8, it is observed that maximum respondents (79.05%) discuss with the family
People usually discuss with family members and community people about earthquake. Therebuildings
in thisarea are vulnerable and require detail evaluation and tenacious action formembers rather
than thecommunity.
is disparitystructuralin theimprovement
frequency(seeof Figurediscussion
amongfamilyand community
people.
-7). Other
wise allof thesemembers
buildings shouldcollapse if
an intenseof earthquake
strikes on the
area.
From Figure-8,
it magnitude
is observedthat maximum
respondents(79.05%) discuss with the family

members rather
than theWITH
community.
4.9 DISCUSSIONFAMILY MEMBERS AND COMMUNITY ABOUT EARTHQUAKE
People usually discuss with family members and community people about earthquake. Thereis disparity in the frequency of discussion among family members and community people.
From Figure-8, it is observed that maximum respondents (79.05%) discuss with the family
members rather than the community.

Figure-8: Comparison in Discussion with Family Members and Community about Earthquake
4.10 RESPONDENTS PLAN TO DO DURING AN EARTHQUAKE OCCURRENCE
Figure-8:
Comparison
in Discussion
withsurveyed
Family Members
Community
about
Thoughmostof the respondents
in thearea felt andearthquake
which
wasEarthquake
finished
beforeanything,
allLANof TO
themhave certain
plan of responses
in case of earthquake
4.10doing
RESPONDENTS PDO DURINGAN EARTHQUAKEOCCURRENCE
Figure-8: Comparison in Discussion with Family Members and Community about Earthquake

occurrence. From Figure-9, it is clear that they give more importance to run out of home
4.10 RofESPONDENTS PLAN TO DO
AN EARTHQUAKEOCCURRENCE
Though mostthe respondents
inDURING
the surveyed
area felt
earthquake which was finished
immediately. They also have plan to try to go to a safe place like open field, big hall room,
before doing
anything,
allrespondentsof them inhavecertainarea
plan
responses
caseof earthquake
Thoughmost of thethe surveyed
feltofearthquake
whichinwas
finished
stay under table or bed, take position near column etc to save their lives of themselves andbeforedoing
anything, it
all isof clearthem haveplan ofmore
responses
in case of toearthquake
occurrence.
From
Figure-9,that certain
they giveimportancerun out of homefamily members.
occurrence. From Figure-9, it is clear that they give more importance to run out of home
immediately. They also have plan to try to go to a safe place like open field, big hall room,
immediately. They also have plan to try to go to a safe place like open field, big hall room,

stay understay
table
ortablebed,or takeposition
to save
theiroflivesof themselves
and
under
bed, takepositionnear
near column
column etcetc
to save
their lives
themselvesandfamily members.
family members
.

137

137

of Respondent's
During anan Earthquake
AttackFigure-9:Figure-9:
Plan ofPlan
Respondent's
DuringEarthquake
Attack137121Figure-9: Plan of Respondent's During an Earthquake Attack

March 2010

4.11 PARTICIPATION IN EARTHQUAKE AWARENESS PROGRAM
It is found from field survey that 30% respondents took part in earthquake awarenessprogram like seminar, workshop, and training or drill, mostly organized by different nongovernment organization (NGO) and educational institutions. Amongst the trained
respondents, 83% have taken part in earthquake awareness training, seminar or workshop
organized by NGOs in educational institutes like school, university etc and 13% community
people also got training from Bangladesh Red Crescent Society (BDRCS) (see Figure-10).

Figure-10: Earthquake Awareness Training Program Attained by Respondent

5. PRESSURE AND RELEASE MODEL
After the social vulnerability assessment of the study area the Pressure and Release Model(PAR model) is set up on the basis of existing condition of the community. This model isprepared for showing how an earthquake induced disaster occurs when it affects vulnerable
people. For the occurrence of any disaster t there is a series of social factors which causes
hazard and generates vulnerability to the people. Their vulnerability is rooted in social
processes and underlying causes which may ultimately be quite remote from the disasterevent itself. The basis for the Pressure and Release model is that a disaster is the intersectionof two opposing forces: those processes generating vulnerability on one side, and the natural
hazard event (or sometimes a slowly unfolding natural process) on the other. The release
idea is incorporated to conceptualize the reduction of disaster, to ease the pressure, and to
reduce vulnerability.
In PAR model, root causes, dynamic pressures, and unsafe conditions apply pressure on thosein vulnerability. For the study ward, root causes are unequal economic distribution, prejudice
towards their social minority, these manifest a progression in vulnerability through dynamic
pressures like lack of knowledge about an earthquake and building construction rules andregulations, inadequacies in training etc. These dynamic pressures produce unsafe conditions

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inthe physicaland social
environments of
those persons
and groups
most susceptible
toinin thethe physicalphysical andand socialsocial environments
environments ofof thosethose persons
persons andand groups
groups most
most susceptible
susceptible totovulnerability
torisk.
Physicallyunsafeconditions
includeunsafeandnon-engineered
vulnerability
vulnerability toto risk.
risk. Physically
Physically unsafe
unsafe conditions
conditions include
include unsafe
unsafe andand non-engineered
non-engineeredbuildings (39%(39% URM buildings)
buildings) due toto design faults,
faults, aged andand damaged building,building, narrowbuildings
buildings (39% URM
URM buildings) due
due to design
design faults, aged
aged and damaged
damaged building, narrow
narrow
staircase(55%
residingbuilding).
Sociallyunsafeconditions
include
risks
to
local
staircasestaircase (55%(55% residing
residing building).
building). Socially
Socially unsafe
unsafe conditions
conditions include
include risks
risks toto local
local
economies;
most
of
the
businesses(21%
businessman)run
inground
floor
or
at
front
side
of
economies;
economies; most
most ofof thethe businesses
businesses (21%(21% businessman)businessman) run
run inin groundground floor
floor oror at
at front
front side
side ofofthebuilding
and
upper
floor
used
as
residential
purposeandunsafeconditionsindifferentthethe buildingbuilding andand upper
upper floor
floor used
used asas residential
residential purpose
purpose andand unsafe
unsafe conditions
conditions inin different
different
factories
like
printing
andpackaging,workshop,mechanicalworkshop,
recyclingindustry,
factories
factories like
like printing
printing andand packaging,packaging, workshop,mechanicalworkshop,mechanical workshop,
workshop, recycling
recycling industry,
industry,bottlefactory
etc
and
lack
of
mobilityofelderlypersons
duringearthquaketoescapeandbottlebottle factory
factory etc
etc andand lacklack ofof mobility
mobility ofof elderly
elderly persons
persons during
during earthquake
earthquake toto escapeescape andandinstitutional weakness
weakness inin thethe implementation
implementation ofof disasterdisaster management
management planningplanning andand lacklack ofof
institutional
institutional weakness in the implementation of disaster management planning and lack of
coordinatedaction. In
the rootcause phaseof thismodel, themost importantroot causes
arecoordinatedcoordinated action.
action. In
In thethe root
root cause
cause phase
phase ofof thisthis model,
model, thethe most
most important
important root
root causes
causes are
are
those
which
have
an
economic,demographic,orapolitical
foundation.
Thesefoundations
those
those which
which have
have anan economic,
economic, demographic,
demographic, oror aa politicalpolitical foundation.
foundation. These
These foundations
foundations
affectsociety’ssocial,financial,
andpolitical
systemsandsometimes
influenceon theaffectaffect society’s
society’s social,social, financial,financial, andand politicalpolitical systems
systems andand sometimes
sometimes influence
influence onon thetheallocation
anddistributionofresources,
among
differentgroupsofpeople.
Figure-11
isanallocation
allocation andand distribution
distribution ofof resources,
resources, among
among different
different groups
groups ofof people.
people. Figure-11
Figure-11 is
is an
anattempt
toidentify
thefactors
which
could
be
adoptedbytherespective
authorities
toreduceattempt
attempt toto identify
identify thethe factors
factors which
which could
could bebe adopted
adopted byby thethe respective
respective authorities
authorities toto reduce
reducethe pressurepressure before
before any
any upcoming
upcoming earthquake
earthquake event.
event. (Blakei(Blakei etet al.,
al., 2003)
2003)
the
the pressure before any upcoming earthquake event. (Blakei et al., 2003)

ADDRESSROOT
ADDRESSROOT
ADDRESSROOT
CAUSESCAUSESCAUSES
PrejudicePrejudicePrejudicetowards
towards
towards
ethnicethnicethnicminorities
minorities
minorities
andsocialandsocialandsocial
group
group
group
UnequalUnequalUnequaldistributio
distributio
nndistributio
of
n of
of
economic
economic
economic
power
power
power inBeliefBeliefBelief ininmodernizmodernizmoderniz
ation
and
ation
and
ation
and
sciencesciencescience

REDUCEPRESSURES
REDUCE
REDUCE PRESSURESPRESSURES
ReducePressures
ReduceReduce Pressures
Pressures
Raise
awareness
Raiseawareness
Raiseawarenessamongtheresidents
amongtheresidents
among therespondents
residents(30%(30%
respondents(30%
respondents
participatesinparticipatesinparticipates workshop,
intraining,
training,
workshop,training, byworkshop,
seminarNGO’s
seminarNGO’s
seminar by
by
NGO’s
School,Bangladesh
School,Bangladesh
School,Bangladesh
Red
Crescent
Society,Red
Crescent
Society,Red
Crescent
Society,Fire
serviceetc)Fireservice
etc)
FireEarthquake
service etc)
Earthquake
Earthquake
resistancehousing
resistancehousing
resistancehousing ofReconstruction
ReconstructionofReconstruction
of
old
and
damagedoldanddamagedoldanddamagedbuilding(64% old
andbuilding
oldbuilding (64%(64%
old andanddamaged)damaged)damaged )MacroForcesMacro
Macro Forces
Forces
Improveeconomic
Improve
Improve economic
economicopportunities
toreduceopportunities
toreduceopportunities
toreduceurbanization
urbanization
urbanization
DecentralizationofDecentralizationofDecentralizationofeconomic
activities.
economic
activities.
economic activities.

ACHIEVE SAFE CONDITIONSCONDITIONSACHIEVE
ACHIEVE SAFE
SAFE CONDITIONSREDUCE
Protected
REDUCE
Protected
REDUCE
Protected
HAZARDS
Environment
HAZARDS
Environment
HAZARDS
Environment
Impro
Impro
Implementation
Impro
Implementation
ved
Implementation
ved
of
BNBC
and
ved
of
and
seismicof BNBC
BNBC
andseismic
RAJUK
set
back
seismic
RAJUK
set
back
hazard
RAJUK
set
back
hazardrules
duringhazardrules
duringmappingrules
duringmappingplanning
andmappingplanning
and(Implemplanning
and(Implemconstruction(Implemconstruction
entationconstruction
entation
Strengthen
entation
Strengthen
ofStrengthen
REDUCofexistingbuilding
REDUCofexistingbuilding
REDUCMicrozo
existingbuilding
TION
OF
Microzothrough
TION
OF
MicrozothroughTION
OFnationthrough
DISASTER
nationDISASTER
retrofitting
nationretrofitting
DISASTER
mapof
retrofitting
RISK
map
RISK
Review
map ofof
Review
RISK
Dhaka
ReviewDhaka
densitiesin
Dhaka
densities
incity onon
densitiesvulnerableincitycertaincity
oncertainvulnerable
land
use
certainvulnerable
land
use
structures
by
land
use
structuresbyplanning
structures patterns
byplanningchanging
planningchanging
patterns
and allallchanging
patterns
and
of
land
use
and
all
of
kind
of
of landland use
use
kind
of
kind
of
develop
PublicActiondevelop
Publicdevelop
Public Action
Actionment )
ment
ment ))
Improve
Improve
ImprovedisasterAutodisasterAutodisasterAutopreparedness
mated
preparedness
mated
preparednessmatedplanning
event
planning
event
planning
event
warning
warning
warning

Figure-11:
Release of
Pressure to
Reduce Earthquake
Figure-11:
Figure-11: Release
Release ofof Pressure
Pressure toto Reduce
Reduce Earthquake
Earthquake

139
139
139123

March 2010

6. VULNERABILITY ASSESSMENT OF THE PUBLIC BUILDINGS PROPOSED AS
EVACUATION SHELTER
There are many public buildings in the study area. Public buildings are selected on the basisof land use as religious center, school, college, community center, meeting place etc. In thisstudy area twenty seven public buildings and three playfields are selected for the evacuationof inhabitants while an earthquake strikes. Many features are considered to assess the publicbuildings as evacuation place for the dwellers of selected study area.
6.1 ASSESSMENT OF PUBLIC BUILDINGS USING RVS SCORE
Mainly three types of structures- C3, C2 and URM are found in the study ward. But among
the public buildings 81% have C3 structure and only 19% have URM structure. Among them
56% public buildings RVS score is greater than two and 44% buildings score less than two.
These buildings require further detail analysis.
6.1.1 PLAN AND VERTICAL IRREGULARITY
Irregularity in building plan is a deviation from a rectangular plan. Such deviation from plan
irregularity leads to irregularities in stiffness and strength distributions, which in turn increase
the risk of damage localization under strong ground excitations. In earthquake resistantdesign, regularity in plan is encouraged. In the study area a number of public buildings haveirregularity in plan. About sixteen buildings have rectangular shape and eleven buildings
have irregular plan. It has found from field survey that 89% public buildings in the study area
have regularity in their elevation shape i.e. they are vertically regular and 17% buildings haveirregular shape.

Photo 7: Vertical Irregularity of Building

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6.1.2 HEIGHT OF THE PUBLIC BUILDING
It has observed that among all public buildings in the study area 70% are one to three storied
and only 9% buildings are more than six storied (see Figure-11). It has also found that only
two public buildings (Islampur Jame Mosque and Zindabahar Jame Mosque) are sevenstoried.

Figure-11: Height according to storey of Public Building
6.2 ASSESSMENT OF PUBLIC BUILDINGS USING TURKISH LEVEL-I AND LEVEL-II METHOD
A more detail analysis of buildings is done in Turkish Level-I & Level-II method incomparison with the RVS method. It has been found from other studies that the Turkishmethod is more compatible in the circumstances of Bangladesh. The detail evaluations of 21
structures which are proposed to be the evacuation sites are done (see Table 3). For detailstudy of the building Turkish Level-II has executed and many aspects of the building isassessed such as pounding effect, overhang, short column, soft storey, apparent quality of thebuilding.
6.2.1 SOFT STOREY OF THE PUBLIC BUILDINGSoft storey buildings are open ground storey buildings, consistently shown poor performance
during earthquakes. A significant number of them have collapsed. In the study area it has
found that 95% buildings have no open ground and only 5% public buildings have open
ground i.e. presence of walls at upper storey (see Figure-12). In accordance with CDMP, 30%
buildings in this Ward have soft storey. The existence of walls in upper storey makes themmuch stiffer than the open ground storey. The existing open ground storey buildings need to
be strengthened suitably so as to prevent them from collapsing during strong earthquake
141125

March 2010

shaking. The owners should seek the services of qualified structural engineers who are able tosuggest appropriate solutions to increase seismic safety of these buildings.

Figure-12: Soft Storey of the Public Building
Table 3: Turkish Method Performance Score and RVS Score
Public Building

126

Turkish Method
Level I Level II
surveySurveyRVS Score

Ahmed Bawni College

75

85

1.9

Ahmed Bawni School

75

85

1.9

Anandamoyee Girls' HighSchool (Strc-1)

125

125

1.7

Anandamoyee Girls' HighSchool (Strc-2)

125

123

2.2

Anandamoyee Girls' HighSchool (Strc-3)
Haibat Nagar Primary School

115

120

2.2

115

113

1.7

Hammadia School
Islampur Jame Mosque

65

57

2.2
0

Jabbu Khanam Jame Mosque

90

100

1.9

Jummon Community Center

125

125

1.7

Kamranga Jame Mosque

110

106

0

Kashaituli Panchayet
Committee and School
Kona Party Center
Mahuttuli Mosque

80

77

2.4

80
125

85
130

0.4
2.2

Maulana Mosque
Moshjid-e-Baitul Mamur
Samsabad Boro Mosque

125
120
120

130
125
125

2.1
2.2
2.2

Samsabad Primary School

75

72

1.9

Shahjada Mia Jame Mosque

115

118

1.7

Shahjadi Begum Jame

125

121

2.2

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ICUS Report 48
Public Building

Turkish Method
Level I Level II
surveySurveyRVS Score

MosqueZindabahar Jame Mosque

50

47

2.4

6.2.2 OVERHANG OF THE PUBLIC BUILDING

From field survey it has observed that most of the public buildings (84%) have no overhang
in their structures. These buildings expanded without any desecration of as per plan. Only
three buildings (16%) do not follow the plan and design accurately. According to CDMP, it
has found that among all buildings in Ward 68, 77% building do not follow the design andrest of the building follows the plan during construction.
6.2.3 POUNDING OF PUBLIC BUILDING

Pounding between closely spaced building structures can be a serious hazard in seismically
active areas. It is one of the main causes of severe building damages in earthquake. The nonstructural damage involves pounding or movement across separation joints between adjacentstructures. Seismic pounding between two adjacent buildings occur during an earthquake. In
old Dhaka it is conspicuous that most of the buildings are constructed in the means ofcongested way. So that it is evident that 84% building in the study area might face pounding
effect and only 16% buildings are free from this (see Figure-13).

Figure-13: Pounding Effect of Public Building

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March 2010
6.2.4 SHORT COLUMN OF PUBLIC BUILDING

During past earthquakes, reinforced concrete (RC) buildings that have columns of different
heights within one storey, suffered more damage in the shorter columns as compared to tallercolumns in the same storey. The short column is stiffer as compared to the tall column, and it
attracts larger earthquake force. If a short column is not adequately designed for such a large
force, it can suffer significant damage during an earthquake. Figure-14 shows 16% buildings
short column has identified and rest of the buildings (84%) column is designed consistently.
From CDMP, short column of 63% building in the study area are identified and 37% are not
identified. In existing buildings with short columns, different retrofit solutions can be applied
to avoid damage in future earthquakes.

Figure-14: Short Column of Public Building
It is clear that most of the structures fall below the cut-off score in the RVS method but in the
Turkish Method, most of them fall above the cut-off score that is they dont need further
detail analysis.
6.3 CAPACITY OF PUBLIC BUILDING AND OPEN SPACE AS EVACUATION SHELTER
The selected public buildings floor area and total area has calculated. For the calculation ofaccommodation capacity of a building 80% usable area and for play ground or open space
100% usable area is considered and 10sq.ft space per person is considered. Table -4 shows
the capacity of each building to evacuate the residents.
Table-4: Accommodation Capacity of Public Building and Open Space
Public Building /Open Space

Floor
Area

Total
Accommodation
in a Building

Building Name
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ICUS Report 48

Public Building /Open Space

Floor
Area

Total
Accommodation
in a Building

Shahajadi Begum
Mosque7486

599

Kashaituli Panchayet
Committee

4560

365

Babubajar Ghat
MosqueJummon Community
Center

4400

352

15720

1258

Zindabahar Mosque
Haibat Nogor Primary
School

6440
5634

515
451

Mahuttuli Primary
SchoolMahutuli Mosque
Anandomoyee Girls -1
Anandomoyee Girls -3
Anandomoyee Girls -2
Ahmaed Baowani
College

2250

180

5760
12600
2520
1800
24840

461
1008
202
144
1987

Ahmaed Baowani
SchoolSamsabad Primary
School

21120

1690

7500

600

Jabbu Khanam
MosqueHammadia School
Kona Party Center
Mosjid-E-BaitulMamur
Malibagh Peyala
MosqueMokimbazar School
Islampur Jame Mosque
Shahjada Mia Jame
Mosque

10500

840

10800
14000
3000

864
1120
240

3200

256

2250
27300
2544

180
2184
204

Kashaituli Old Jame
Mosque3080

246

Samsabad Boro
MosqueMaoulana Mosque
Kamranga Mosque

9520

762

10080
5268

806
421

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March 2010

Public Building /Open Space

Floor
Area

Total
Accommodation
in a Building

Bongshal Rokonuddin
Jame Mosque

8276

662

Open SpaceSamsabad Play Field
Armanitola Play Field
Zindabahar Play Field

13290 1329
20250 2025
60625 6063

Total Accommodation

28012

7. CONCLUSIONSThe local people are main focus of this study as they will have to face the disaster and theirinstant response in that time will measure the level of losses after the strike. From theassessment it is found that most of the surveyed people are more or less knows about
earthquake and dont have any idea that what have to be done in preparatory phase, during
and after the occurrence of the event. A small portion of them got some training arranged bydifferent organizations. The main problem is the built environment

with faulty defective

infrastructure, narrow road network and the lack of open spaces along with many othersymptoms that made the locality vulnerable to earthquake. The main concern is the lack ofopen spaces. After the earthquake, one should come out from the building and take shelter toopen areas. If the people of the vulnerable areas are provided with an evacuation plan they
can be aware of that and the loss due to earthquake hazard may be reduced to a great extent.

REFERENCES
Bangladesh Bureau of Statistics (BBS). (2001) Small Area Atlas of Bangladesh”,
Planning Commission, Ministry of Planning, Dhaka.
Bangladesh Bureau of Statistics (BBS). (2009) Statistical Pocket Book of Bangladesh
2008” Planning Commission, Ministry of Planning, Dhaka.
Blakei. P, Cannon, T., Davis, I., Wisner, B. (2003), "At Risk: Natural Hazards, Peoples'
Vulnerability and Disasters." 2nd Ed., Routledge, London, pp 49-56 & 275-303.
Jahan. I; Ansary. M.A. (2007), School Earthquake Safety Program (SESP) in Old Dhaka,Bangladesh” proceedings of International Conference USMCA-2007, Dhaka, Bangladesh.
Oldham R.D. (1899). Report on the Srimangal Earthquake of 12th June 1918, Memoir ofGeological Survey of India”, Volume 29, pp 1-349.
130

BNUS Annual Report-2009146

PART-III
STRONG MOTION MONITORING SYSTEMS IN
BANGLADESH: 2007 TO 2009

Prepared By
Md. Shamsur Rahman
Mehedi Ahmed Ansary

BANGLADESH NETWORK OFFICE FOR URBAN SAFETY(BNUS), BUET, DHAKA

147

ICUS Report 48

ABSTRACT
Five large earthquakes occurred surrounding Bangladesh between 1869 and 1930. Recently
no large earthquakes occurred in this area. A large earthquake may occur any time in the
future. For seismic hazard analysis earthquake monitoring is important. To measure groundmotion within Bangladesh, seven accelerometers was deployed within a 60 km radius of
Jamuna Bridge in 2003. Another 34, Strong motion accelerographs (SMAs) were deployed in
PWD offices all over Bangladesh. This accelerometers and accelerographs give data inNorth-South, East-West and Up-Down direction. For the last couple of years, twelve
earthquakes are recorded by these accelerometers and SMAs. It is hoped that the system will
yield valuable data to the local researchers to have better ideas on the performance of the
SMA sites as well as seismic activities of the whole region. The relationship between
magnitude, epicentral distance and peak ground acceleration of those earthquakes constitutethe basic parameter needed for assessing seismic hazard at a given site. This paper presents
earthquake ground motion within Bangladesh recorded by the installed accelerometers and
SMAs between 2007 and 2009.

1. Introduction
An earthquake is a sudden and violent motion of the earth usually caused by volcanic
eruption, plate tectonics, or man-made explosions which lasts for a short time, and within avery limited region. Most earthquakes last for less than a minute. The larger earthquakes arefollowed by a series of after-shocks which also may be dangerous. Volcanic eruption or plate
tectonics is responsible for causing earthquakes. Also small earthquakes can be caused byblasting, quarrying and mining. Man made earthquakes are like underground nuclear
explosions. But plate tectonics cause large number of big earthquakes. The low incidence ofsevere earthquakes during the century has led to a situation where most of the population andpolicy makers dont perceive seismic risk to be important. For this purpose there are thirtyfour analog SMAs obtained from USGS were deployed in free-field (on ground) at different
PWD offices all over Bangladesh, especially in moderately seismic zoning areas such as
Chittagong, Sylhet, Dhaka, Mymensingh, Rangpur, and Sathkhira district. The Strong Motion
Accelerograph must be situated in the ground surface, soil condition to be hard or sandy soil.
The rapid urbanisation, development of critical engineering works, industrialization of cities
with modern types of buildings and the concetration of populations living or settling inhazardous areas are matters of growing concern, as they contribute to heavier loss of life andincrease considerably the cost of disaster damage. Macroseismic earthquake data of thehistorical earhquakes are important for seismic hazard analysis. The relationship between
magnitude, epicentral distance and peak ground accleration of these earthquakes constitutethe basic parameter needed for assessing seismic hazard at a given site.

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March 2010

2. Objectives
During the last two centuries, Bangladesh and its neighbouring region have experienced
several large earthquakes. The peak ground acceleration of these earthquakes has been
estimated using different existing attenuation law. But for earthquake hazard analysis, unified
acceleration attenuation relationship for Bangladesh is required. The major objectives of thestudy are as follows:(a) To develop an acceleration based attenuation relationship for Bangladesh and itssurrounding region.
(b) To obtain building respones during an earthquake(c) To obtain strong motion data which can be used to update BNBC 1993(d) To exchange earthquake data with neighbouring countries
3. Earthquake Monitoring System in Bangladesh
Strong Motion Acclerograph (SMAs) is an analog earthquake data recording equipment.
Thirty-four analog SMAs obtained from USGS were deployed in free-field (on ground) at
different PWD offices all over Bangladesh, especially in moderately seismic zoning areas
such as Chittagong, Sylhet, Dhaka, Mymensingh, Rangpur, and Sathkhira district. The
operating and Monitoring Phase of the project has started on April 01, 2005 and after
instalation on SMAs every two or three month latter than to be check the SMAs instrument
such as, changing in rechargeable battery, recheck outer fencing in the instrument, battery
voltage, connection, trigger value set-up and earthquake data collection for all free-fieldstations. This accelerometer gives data in North-South, East-West and Up-Down direction.
The initial goal of the project is to develop an earthquake time history database for different
soil condition and different earthquakes of Bangladesh. After compilation of a number ofearthquakes, this database will be used to develop attenuation law for Bangladesh.

4. Earthquake Records
The installation of 34 SMAs at PWD offices all over Bangladesh and within BUET campus
was completed in the end of March 2005. From April 2005 to November 2009, these SMAs
recorded the following earthquakes:
May 30, 2006 : Bay of Bengal Earthquake
August 05, 2006 : Jessore Earthquake
November 03, 2006 : Myanmar-India Earthquake
November 10, 2006 : Bangladesh-India Earthquake
July 28, 2007: India-Myanmar Earthquake
November 07, 2007: Bangladesh-Myanmar Earthquake (1)March 20, 2008: Modhupur Earthquake
July 05, 2008: Rajshahi Earthquake
July 27, 2008: Haluahhat Earthquake
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ICUS Report 48

August 23, 2008: Bangladesh-Myanmar Earthquake (2)January 06, 2009: Tangail Earthquake
September 21, 2009: Bhutan Earthquake
4.1 July 27, 2008: Haluahhat Earthquake
On July 27, 2008 an earthquake was recorded by the free-field stations Netrokona,
Kishoreganj, sherpur, jamalpur, Hobiganj, Rangpur and Nilphamari at 12:55:58 hrs BST(18:52:58 hrs GMT, July 27, 2008). Magnitude of this earthquake was 4.8 and depth was 44
Km. Maximum acceleration of this earthquake in Jamalpur was 54.3198 cm/sec.2 and it wasin North-South direction.

4.2 September 21, 2009: Bhutan Earthquake
Last on September 21, 2009 Bhutan Earthquake was recorded by the free-field stations
Panchagarh, Dinajpur, Lalmonirhat, Rangpur and Airport Hazi-camp at 14:40:45 hrs BST(08:40:45 hrs GMT, September 21, 2009). Its Magnitute was 5.5 and depth was 16Km.
Maximum acceleration of this earthquake in Dinajpur was -48.0967 cm/sec.2 and it was in
East-West direction.

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March 2010

Figure: 1 Strong Motion Accelerograph Machine
400

250

250

250

A

250

900

400

A

F i r s t s ta g e
o f c a s ti n g

900 m m
PLA N
400

45

S e c o n d s ta g e
o f c a s ti n g

250

150

3 -1 0 m m d ia
( b o th w a y )

250

100

6 m m d ia n u t

900
S E C : A -A

7 - 1 2 m m d ia b a r( b o th w a y )N O T E : A l ld i m e n s i o n s a r e in m m .
C o n c r e t e to b e u s e d 1 : 2 :4

Figure: 2 Concrete Base Foundations for SMA-Instrument

134

BNUS Annual Report-2009

ICUS Report 48

BHU

Panchaga

HAL

TAN
RAJ

MOD







  




 
BDM




BDM 



Figure.3

Sign indicates the location of SMA-site andSign indicates the name and location of Earthquake.

Figure 3. Location of earthquakes and SMAs

Figure 4.
Earthquake Digital
Equipment
Figure4. ETNA
ETNA-Earthquake
DigitalEquipment

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March 2010
TableTable
1.Summaryof Recorded
earthquake
differentaccelerometer
accelerometershows
in below
1.Summaryof Recorded
earthquakeevents
events with different
areareshows
in below
CODECODE
Name
Occurrence Latitude
Latitude Longitude
Longitude
Name ofthe of the
Occurrence
earthquake(deg.)(deg.)
earthquake
datedate(deg.)(deg.)

Magnitude
Magnitude

Depth
Depth
(km)
(km)

Maximum
Maximum
recordedrecorded
acceleration
acceleration
2(cm/sec ) 2

Recordedsite site
Recorded(cm/sec )BAY
BAY MAY30
30.05.2006
20.60ºN
Bay of Bengal
MAY30
20.60ºN
2006 30.05.2006
Bay of Bengal
2006 JES AUG
JessoreJES AUG 05
05.08.2006
23.10ºN
Jessore05 2006 05.08.2006
23.10ºN
2006 MID
MIDNOV 03
Mynmar
03.11.2006
22ºN
NOV 032006
India
Mynmar

2006

India

03.11.2006

BDI
NOV 10
BDI 2006

BangladeshNOV 10
India 2006

Bangladesh
IndiaIndia

10.11.2006

IDM JUL
28
2007
IDM JUL

MynmarIndia
Mynmar28
2007

10.11.2006

28.07.2007

28.07.2007

BDM
NOV 072007

Bangladesh
Myanmar BDM

07.11.2007

NOV 072007 MOD 07.11.2007

Bangladesh
MyanmarModhupurMAR 202008

20.03.2008

MOD
MAR 20
2008RAJ JUL20.03.2008

Modhupur05
2008

Rajshahi

Rajshahi

24.60ºN

22.80ºN

22.80ºN
22.80ºN

22.80ºN
23.60ºN

23.60ºN
24.4ºN

24.4ºNHAL JUL
27 BDM
2008AUG 2327.07.2008

23.60ºN

2008

Bangladesh
MyanmarBangladesh
Tangail
Myanmar24.60ºNRAJ JUL
05 HAL JUL
2008 27 05.07.2008

Haluaghat

Haluaghat

05.07.2008

22ºN

2008

27.07.2008

22.08.2008

BDM
AUG 23TAN
JAN 062008
22.08.2008
2009

06.01.2009

23.60ºN

22.80ºN

22.80ºN

24.39ºN

TAN BHU
JAN 06SEP 21
22.09.2009 24.39ºN
24.50ºN
TangailBhutan 2009 2009 06.01.2009

91.94ºE

91.94ºE

89.20ºE

4.7

29

16.0

Agrabad, Rahamatganj and Coxbazar

Meherpur and Sathkhira

4.7

29

16.0

Agrabad, Rahamatganj and Coxbazar

89.20ºE

4.0

4.0

15

24.0

93.30ºE

5.2

33

34.0

93.30ºE

5.2

33

92.60ºE

5.0

33

92.60ºE

5.0

33

93.30ºE

4.8

1593.30ºE

4.8

1592.60ºE

5.3

1592.60ºE

5.3

1589.75ºE

4.2

25

89.75ºE

4.2

25

32.0

88.5ºE

4.1

29

42.9893

88.5ºE

4.1

29

91.20ºE

4.8

4491.20ºE

4.8

4492.60ºE

4.9

25

92.60ºE

4.9

4.0

10

19.72705

Jamuna bridge East site, West site, Bogra
and Natore Chittagong(Rahmatganj)

88.75ºE
89.75ºE

5.5
4.0

60
10

48.0967
19.72705

Panchagarh,Dinajpur,Lalmonirhat,Rangpur
Jamuna bridge East site, West site, Bogra
andandAirportHazi camp.
Natore89.75ºE

15

25

24.0

34.0

34.0

34.0

32.0

32.0
96.0

96.0
32.0

42.989354.319854.3198
58.5964

58.5964

Meherpur and Sathkhira

Rahamatganj, Coxbazar, Bandanbhan,
Khagrachari and
Rangamati
Rahamatganj,
Coxbazar,
Bandanbhan,

Khagrachari and Rangamati
Sylhet, Sunamganj, Moulovibazar andHobiganj

Sylhet, Sunamganj, Moulovibazar andHobiganj

Rahamatganj, Bandarbhan, Khagrachari and
Rangamati

Rahamatganj, Bandarbhan, Khagrachari and
Rangamati
Rahamatganj, Bandarbhan,
Khagrachari,Coxsbazar and Rangamati

Rahamatganj, Bandarbhan,
Khagrachari,Coxsbazar and Rangamati
Airport Hazicamp ,jamalpur and Serajganj
Jamuna Bridge east and west end.

Airport Hazicamp ,jamalpur and Serajganj
Jamuna Bridge east and west end.
Chapai nawabganj

Chapai nawabganj

Sherpur, Jamalpur, Netrokona, Kishoreganj,
Hobiganj, Rangpur and

Sherpur, Jamalpur, Netrokona, Kishoreganj,
Rangamati,
Bandarban
and andHobiganj,
Rangpur
Chittagong(Rahmatganj)

Rangamati, Bandarban and

BHU
BhutanSEP 21 2.Summary of Ground Motion in Free field Stations due to (Haluaghat)
Table
Mymensingh
Panchagarh,Dinajpur,Lalmonirhat,Rangpur
2009
22.09.2009
88.75ºE
5.5
60
48.0967
Earthquake
on July 27,24.50ºN
2008
and Airport Hazi camp.

Table 2.Summary of Ground Motion in Free field Stations due to (Haluaghat)
Earthquake on July 27, 2008

136

153
Mymensingh

BNUS Annual Report-2009
153

BHU
SEP 212009

Bhutan22.09.2009

24.50ºN

88.75ºE

5.5

60

48.0967

Panchagarh,Dinajpur,Lalmonirhat,Rangpur
and Airport Hazi camp. ICUS Report 48

Table 2.Summary of Ground Motion in Free field Stations due to (Haluaghat)
Earthquake on July 27, 2008

Station ID#

Channel

Date

Time
(GMT)

Latitude&Longitude

Mymensingh

Derived Max.
Peak153
GroundAcceleration(cm/sec2 )EW
SherpurUD

10.9215
27.07.2008

18:52:58

23.25ºN
89.64ºE

NS

38.4383

EW
JamalpurUD

Netrokona32.4108
27.07.2008

18:52:58

23.19ºN
89.94ºE

29.1048

EW

10.219327.07.2008

18:52:58

23.15ºN
8924ºE

22.8482NS

9.7069EW

9.1392

UD

27.07.2008

18:52:58

23.01ºN
89.14ºE

9.053
18.0918NS
Note.

6.3360NS

UD

Kishoreganj

6.4647

EW represents East West direction
UD represents Vertical direction
NS represents North-South direction

Table 3.Summary of Ground Motion in Free field Stations due to Bhutan Earthquake on September
21, 2009
NS
Station ID#
Dinajpur
Panchagarh
Lalmonirhat

EW
Channel

Date

UD

Time
(GMT)

Latitude&Longitude
23.60ºN
88.60ºE

NS
EW
UD
EW

21.09.2009

14:40:45

21.09.2009

14:40:45

23.50ºN
88.50ºE
23.50ºN
88 75ºE

DerivedMax.
24.2571
Peak
48.09671
GroundAcceleration
7.57362 )(cm/sec
28.042318.4730
32.3755
20.8127

137

154

March� 2010
Table 3.Summary of Ground Motion in Free field Stations due to Bhutan Earthquake on September
21, 2009
�
Derived��
Max.�Peak�
Note.�
Latitude�Ground�Time�
Station�ID#
Channel� ����Date�&�
Acceleratio(GMT)�
Longitude�
n�(cm/sec2 )EW�Panchagarh

UD�
NS�

��Dinajpur��������
Lalmonirhat������Rangpur

EW�
�
UD�
�
NS�
�
EW�
UD�
NS�
EW�
UD�
NS�

Airport�Hazi�Camp�

EW�
UD�
NS�

�
�
�
21.09.200
9�
�
�
�
�
21.09.200
9����
21.09.200
9���
21.09.200
9�
21.09.2009�����14:40:45�
����
14:40:45����
14:40:45�

�28.0423�
23.50ºN�
88.50ºE�����32.3755��24.2571��48.09671�

23.60ºN�
88.60ºE�

7.5736��18.4730�
�20.8127�

23.50ºN��88.75ºE���
14:40:45�

23.50ºN����
88.70ºE�

21.09.200
9�

24.50ºN����������89.70ºE�

17.3437��34.6037�
11.2247�
6.2363��24.4358��23.56�
14.25�
�22.36��
EW�represents�East�West�direction����������������UD�represents�Vertical�direction�
NS represents North-South direction�Conclusions

The first earthquake recorded by SMAs was the Bay of Bengal Earthquake on May 30, 2006
and Last on September 21, 2009 Bhutan Earthquake was recorded by the free-field stations
Panchagarh, Dinajpur, Lalmonirhat, Rangpur and Airport Hazi-camp at 14:40:45 hrs BST(08:40:45 hrs GMT, September 21, 2009). Its Magnitute was 5.5 and depth was 16Km.
Maximum acceleration of this earthquake in Dinajpur was -48.0967 cm/sec.2 and it was in
East-West direction. By recording this earthquake event, the installation of the earthquake
monitoring system for Bangladesh entered in to an interesting stage. The earthquake, which
was a minor one, is estimated to be located close to the SMA site. This paper prsents analysis
result of this particular earthquake data recorded nine free field stations namely, Sherpur,
Jamalpur, Netrokona, Kishoreganj, Panchagarh, Dinajpur, Rangpur, Lalmonirhat and Airport
Hazi-camp. After installation the system so far recorded twelve earthquakes. It is hoped that138

BNUS Annual Report-2009
155

ICUS Report 48



the system will yield valuable data to the local researchers to have better ideas on theperformance of the SMA sites as well as seismic activities of the whole region. For the next
few years compilation of such earthquake data is needed to develop the attenuation law for
Bangladesh. This attenuation law will help us to develop the seismic zonation map for
Bangladesh.
References
Ansary, M.A. and M. Ali (2001). Seismic Risk of Dhaka City and Role of the Insurance
Community, 5th Asia-Pacific Risk and Insurance Association (APRIA) Conference, July 1518, 2001, Bengalore, India.
Ansary, M. A, Rahman, S.M (2007). “Strong Motion Monitoring System in

Bangladesh”

Second International Earthquake Symposium, December 9-10 BUET-Dhaka-Bangladesh.
BNBC (1993). Bangladesh National Building Code, HBRI-BSTI.
Hudson, D.E. (1979). Reading and Interpreting Strong Motion Accelerograms, EERI, USA.
KMI User’s Manual (1997). SMA SCANVIEW PLUS - scanner-based software for film
accelerogram digitization.
Morgan, J. P. and McIntire. (1959). Quaternary geology of Bengal basin, East Pakistan andIndia, Bulletin of Geological society of America, Volume 70, pp. 319-342.
Oldham, R.D. (1899). Report on the Srimangal Earthquake of 12th June 1918, Memoir ofGeological Survey of India, Volume 29, pp.1-349.
SMA-Report-09 (April 2009) Installation of an Earthquake Monitoring sytem for Bangladesh

156139

140

BNUS Annual Report-2009

   

   

  

March 2010

141 

 

 

 

 

 ICUS Report 48

PART-IV
GEOPHYSICAL SURVEYS AT SRIMANGALAREA, SYLHETPrepared By
Md. Saidur Rahman
Ripon Hore
Mehedi Ahmed Ansary

BANGLADESH NETWORK OFFICE FOR URBAN SAFETY(BNUS), BUET, DHAKA

159

ICUS Report 48

INTRODUCTION
BNUS together with Geology Department of Dhaka University performed two types ofGeophysical tests at SriMangal, Sylhet in early January, 2010. The procedure and results aredescribed below.

DETERMINATION OF ELECTRIC RESISTIVITY OF SOIL
Objective of the Test:
To determine the subsurface soil characteristics and ground aquifer.
Equipments:
Hammer6 Pieces steel electrodes
Tape
Joint rod.
CablesGPS
Magnetic Compass
Battery
Electric resistivity Meter

Figure 01: Resistivity meter

Figure 02: Battery

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March 2010

Figure 03: GPS

Figure 04: Magnetic Compass

Field Procedure:
1. The electric Resistivity Test of Soil is not sensitive to ground vibration like Shallow
Depth Shear wave velocity. As a result, special consideration for vibration is notmandatory for this test. But the adjacent electric or magnetic field will affect the Test
Result. So this consideration should be justified before Testing.
2. Before arranging the device for this Test, locations are selected considering the SPT
bore hole locations and Geographical position is assessed with GPS.
3. All the equipments (Resistivity meter, Battery, Electrode etc.) are connected with thecables (See Figure 05).

Figure 05: Arrangement of equipment

Figure 06: Data recording

4. To adjust the Power of resistivity meter initial data is taken for premonition the soil
resistance. If the resistivity of the soil is not suitable for current flow below the soil,
water should be poured into the soil to create the medium of current flow.
5. After arranging the equipment the potential drop between the electrodes is recorded.
This data is taken on both sides same distance of the device. The potential electrodes
are positioned at 0.5m and 1m distance on the both side of equipment.

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ICUS Report 48

6. This test can be performed up to 50m depth of the soil. So, the location of the groundaquifer within this limit may be identified. (See Figure 05)
7. The power of the source is proportional to the distance of the potential drop. So, thepower of the source is increased with the increased of distance. As a result, more
power is required for increasing the distance from the equipment.
8. The position of the electrode is planned on the basis of the log scale. This test can becovered for long arena.
9. By the potential drop of current the soil resistance and the characteristics of soil iscalculated.(See Figure 06)
Functions of the Devices:
Global Positioning System (GPS): Global Positioning System is used to locate theposition of test. Generally, latitude and longitude are recorded with the GPS device(See Figure 03).
Magnetic Compass: Magnetic Compass is used to identify the geological North
direction and to adjust the field condition with the map. (See Figure 04)
Hammer: Hammer is used to penetrate the steel electrode to the Ground.
Resistivity Meter: Electric resistivity is a device to determine the electric resistance ofsoil below the ground surface.(See Figure 01)
Battery: Battery is used for current supply. (See Figure 01)
Cables: Good quality cables are used for the current flow and to record efficient data.
(See Figure 02)

GEOELECTRIC RESISTIVITY SURVEY

Geoelectric resistivity survey was carried out in the area to follow the variation of subsurface
resistivity variation. 4 electrode Schlumberger Configuration with the maximum current
electrode separation of 50m is used in the survey. 11 soundings are carried out at different
sites covering the area. Measured resistivity values are expressed in the form of profiles,
maps and models.
Figure 1 shows the location of VES points and the direction of the profiles along which thevertical variation of resistivity is shown. 3 profiles CC, AA and BB are selected to follow
the vertical variation of resistivity along these directions. Profile CC extend from NW to SE
while AA and BB from SW to NE direction.

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Fig. 1: Distribution of shallow seismic (SS) and vertical electrical sounding (VES) locationand the direction of electrical profiles in the area

Fig. 2: Resistivity section along line AA

Resistivity section along AA (Fig. 2) in SW-NE direction shows the maximum resistivity
along this profile in south-west corner reaching more than 1500 m at the surface level. But
at the central point the resistivity of the surface soil is below 500 m. With the increase of146

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AB/2resistivity
AB/2
resistivitydecreases
decreasesalong
alongthetheprofile
profileandandbelow
belowAB/2=15m
AB/2=15mresistivity
resistivityisisuniform
uniformandand�mthecentral
centralandisisbelow
below100100�m
mminintheandwestern
westernpart.
part.AtAtthe
thenorth
northeasterneasternpartpartresistivity
resistivityisisa abitbit
higherand�m.
higherandisisabout
about150
150�m.
m.m.

Fig.3:3:Resistivity
Resistivitysection
sectionalong
BB’
Fig.
alongline
lineBBBBBB’ProfileBBBB’along
ProfileBB
alongSW-NE
SW-NEdirection
directionisisininthe
thenorth
northeasterneasterncornercornerofofthe
theareaarea(Fig.
(Fig.1).1).
BB’
Resistivitysection
BB’shows
�mResistivity
sectionalong
alongBB
BB
showsthethehigher
higherresistivity
resistivityabout
about700
700�m
mmisisatatthe
thesouth-west
south-westBB’cornerand�mthecentral
centralandthenorth
northeasterneasternpartpart(Fig.
(Fig.3).3).From
From
cornerandreduces
reducestotoabout
about400
400�m
mmininthe
andininthe
AB/2=5mtoto25m
25mthetheresistivity
resistivityisisbelow
below200200�m
�m
andthethedeeper
deeperresistivity
resistivityzone
zoneshowsshows
AB/2=5m
mmand
resistivitybelow
below100100�m.
�m.
resistivity
m.m.

Fig.4:4:Resistivity
Resistivitysection
sectionalong
CC’Fig.
alongline
lineCCCC
CC’

CC’isisininNW-SE
Resistivity
Resistivitysection
sectionalong
alongCC
CC
NW-SEdirection
directionextends
extendsfrom
fromnorth-west
north-westcornercornertotothetheCC’corner(Fig.
Thesurface
surfacesoil
soilalong
alongthisprofileshows
showsresistivity
resistivityofofabout
about400
400
north-east
north-eastcorner(Fig.1).1).The
thisprofile
�m
exceptthe
zonebetween
�m.
Resistivity
mmexcept
thezonebetweenVES
VES0606andandVES
VES0909where
wherethetheresistivity
resistivityisis700
700�m.
m.m.Resistivity
�m164147164

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reduces gradually downward to less than 100 m. Low resistivity zone becomes thicker
towards north-west and the maximum thickness occurs at VES 6 (Fig. 4).

Fig. 5: Direction of Lines of Fence diagram
Figure 5 shows the direction of the lines used for the construction of the fence diagram. Threelines each in NW-SE and NE SW directions are selected to observe the resistivity variationin vertically and laterally along these lines.

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Fig. 6: Fence Diagram of Subsurface Resistivity Variation

Fence diagram (Fig. 6) also shows rapid variations in resistivity of the surface soil ranging
from about 1500 m in the central part to about 400 m in the eastern and northeastern part.
The following zone shows resistivity below 400 m with higher thickness in the northcentral part. The third resistivity zone shows resistivity below 200 m that continues to theinvestigated depth.

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Fig. 7: Subsurface Resistivity Model (vertical axis AB/2 in meter)

It is evident from resistivity model constructed based resistivity measurements (Fig. 7) that
surface soil resistivity is highly variable and shows resistivity around 1800 m at central
western part. At the central part surface soil resistivity is around 400 m and in the northeastern part soil resistivity is below 200 m. The highly variable resistivity of the surface soil
is related to the relief, composition and moisture content of the soil. The sandy dry soil showshigher resistivity. The resistivity below top soil is uniform and is about 200 m and below
this zone resistivity further reduces to about 100 m or below. The sudden reduction inresistivity below the top soil is related to the ground water table.
The top soil is silty to sandy clay in nature and resistivity of the top soil is controlled by its
composition, dryness and relief. Below top soil the sequence is composed of sand and theresistivity is governed mostly by the texture, compactness, porosity, water content andmineralization of water.

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Subsurface
Subsurface
Resistivity
Resistivity
Maps
Maps
Subsurface
Subsurface
resistivity
resistivity
measuredmeasuredas asa function
a function
of of
depth
depth
areareused
used
to draw
to draw
contours
contours
forfor
AB/2
AB/2
= 1,
= 1,
5, 10,
5, 10,
15,15,
20,20,
25,25,
30,30,
40 40
andand
50m.
50m.
is is
Contours
Contours
drawn
drawn
at at
1m1m
AB/2
AB/2
shows
shows
spatialspatialvariation
variation
andandhigherhigherresistivity
resistivity( ~( 1900~ 1900 m)m)
found
found
to to
occur
occur
at theat thesouth
south
westernwesternpartpart
of ofthethe
area
area
(Fig.
(Fig.
8).8).
Resistivity
Resistivity
gradually
gradually
reduces
reduces
in inthethecentralcentralandandnorth-eastern
north-eastern
side
side
of of
thethearea
area
reaching
reaching
to to~200~200 m. m.
SpatialSpatialvariation
variation
in inthethetoptopsoilsoilreflects
reflects
variation
variationin thein thecomposition,
composition,
moisturemoisturecontent,
content,
compactness
compactness
andandrelief.
relief.
Resistivity
Resistivity
contours
contours
at 5m
at 5m
AB/2
AB/2
(Fig.
(Fig.
9) 9)
shows
shows
thethesimilarsimilarresistivity
resistivity
distribution
distributionas as
in figurein figure
8 reflecting
8 reflecting
thethesimilarsimilarcondition
conditionof ofsubsoil.
subsoil.
Resistivity
Resistivity
contours
contours
at at
10m
10m
AB/2
AB/2
(Fig.
(Fig.
10)10)
indicate
indicate
much
much
lower
lower
resistivity
resistivity
valuesvalueswithwithfluctuations
fluctuations
from
from
70 70
to to
230230 m. m.
Distribution
Distribution
patternpatternof ofresistivity
resistivity
is is
also
also
different
different
fromfromfigurefigure
8 and
8 and
9 for
9 for
AB/2
AB/2
1 and
1 and
5m.5m.
Resistivity
Resistivity
contours
contours
drawn
drawn
forforlargerlarger
AB/2
AB/2
from
from
15m
15m
to to
50m
50m
(Fig.
(Fig.
11to
11to
16)16)
demonstratedemonstrate
more
more
or or
lesslesssimilarsimilardistribution
distributionof ofresistivity
resistivity
indicating
indicating
thethe) indicate) indicate
thetheuniform
uniform
naturenatureof ofsubsurface
subsurface
rock
rock
media.
media.
Resistivity
Resistivity
valuesvalues(40(40to to225225 m m
media
media
as as
a sandya sandy
one.
one.

Fig.
Fig.
8: Subsurface
8: Subsurface
Resistivity
Resistivity
Map
Map
at 1m
at 1m
Depth.
Depth.

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Fig.
9: Subsurface
Resistivity
Map
atDepth.
5m
Depth.
Fig.
9:
Subsurface
Resistivity
Map
Depth.
Fig.
9:
Subsurface
Resistivity
Map
at at
5m5m

Fig.
Fig.
10:
Fig.
10:
Subsurface
10:
Subsurface
Subsurface
Resistivity
Resistivity
Resistivity
Map
Map
Map
at at
10m
10m
at 10m
AB/2.
AB/2.
AB/2.

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Fig.
11:Subsurface
Subsurface
Resistivity
Map15m
Depth.
Fig.
11:11:
Subsurface
Resistivity
Map
at 15mDepth.
Fig.
Resistivity
Map
atat15m
Depth.

Fig.
Fig.
Fig.
12:12:
Subsurface
12:Subsurface
Subsurface
Resistivity
Resistivity
Resistivity
Map
Map
Map
at 20matat20m
20m
Depth.
Depth.
Depth.

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March 2010

Fig.
13: Subsurface
Resistivity
atDepth.
25m Depth.
Fig.
Fig.13:13:
Subsurface
Subsurface
Resistivity
Resistivity
Map
MapatatMap
25m
25mDepth.

Fig.14:
Fig.14:
Fig.14:
Subsurface
Subsurface
Subsurface
Resistivity
Resistivity
Resistivity
Map
Mapatat
Map
30m
30mDepth.
atDepth.
30m Depth.

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Fig.
15:
Subsurface
Resistivity
atDepth.
40m
Depth.
Fig.
15:
Subsurface
Resistivity
Map
at
40m
Depth.
Fig.
15:
Subsurface
Resistivity
Map
atMap
40m

Fig.
16:
Subsurface
Resistivity
Map
at
50m
Depth.
Fig.
16:
Fig.
Subsurface
16:
Subsurface
Resistivity
Resistivity
Map
atMap
50m
atDepth.
50m
Depth.
DETERMINATIONSHALLOW
DEPTH
SHEAR
WAVE
VELOCITY
DETERMINATION
DETERMINATIONOFOFSHALLOWOFSHALLOW
DEPTH
DEPTH
SHEAR
SHEAR
WAVE
WAVE
VELOCITYVELOCITY

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Fig. 16: Subsurface Resistivity Map at 50m Depth.

DETERMINATION OF SHALLOW DEPTH SHEAR WAVE VELOCITY
Objective of the Test:
To determine the soil characteristics and checking the soil profile identified by the SPT-N
172
value.
Equipments:
HammerSteel Plate
Tape
Eleven Geophones
CablesGPS
Magnetic Compass
Battery
Seismograph
LaptopAdditional connector

Figure 01: Seismograph and Battery

Figure 03: GPS

156

Figure 02: Laptop

Figure 04: Magnetic Compass

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Figure 05: Steel Plate and Hammer

Figure 06: Geophone, tape and cable

Figure 07: Hammering to produce soil vibration
Field Procedure:
1. The Test site selection is considered based on the geological dip and strike. For
this Test equipments are assembled parallel to the strike line. Dip is not being
considered in this Test. But both Dip and strike may be considered for calculationof earthquake shear wave velocity.
2. All the equipments (Laptop, Seismograph, Geophones, battery, etc.) are connectedwith cables (See Figure 07) and Geophones are connected in two meters interval
consecutively. (See Figure 06)

Figure 08: Array of Geophones

Figure 09: Connection of Seismograph to Laptop

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3. Before recording amplitude data the surrounding of the site should be considered.
The test is very sensitive to vibration. The surface shear wave is recorded from theTest. The vibration produced by the vehicle movement, Industrial noise, normal
water wave produced by the Wind, etc. can affect test result. Even vibration
produced by walking affects the result. So, these factors should be considered
before recording the data. The vibration for recording the data of soil can be
performed with hammering or without hammering. If the rudimentary amplitude
is not suitable for analysis, hammering with plate is done at the proximity of thegeophones to record the data. After that the data of the vibration of soil is recorded
surrounding at every geophone.(See Figure 08)
4. The wave produced by hammering is refracted and reflected to the soil surface.
The seismograph records these data sensitively at the 2m interval one after another.
This way the amplitude at the 2m interval is recorded on the computer software.
These data will be analyzed to calculate the shear wave velocity.
Functions of the Devices:
Global Positioning System (GPS): Global Positioning System is used to locate theposition of test. Generally, latitude and longitude are recorded with the GPS device(See Figure 03).
Magnetic Compass: Magnetic Compass is used to identify the geological North
direction and to adjust the field condition with the map. (See Figure 04)
Hammer: Hammer is used to create vibration below the geophone. (See Figure 05)
Steel plate: Steel plate is used to make vibration with the hammer. (See Figure 05)
Seismograph: Seismograph is a device to record the amplitude data collected from thegeophones. Seismograph is connected with the cable to geophones.(See Figure 01)
Battery: Battery is used the supply current. (See Figure 01)
Laptop: laptop is used to record and saved data from the seismograph with help of thesoftware.(See Figure 02)

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SHALLOW SEISMIC SURVEY FOR S WAVE VELOCITY (VS) MEASUREMENT

Fig. 1: Distribution of shallow seismic (SS) and vertical electrical sounding (VES) locationand the direction of electrical profiles in the ar

Shallow seismic survey was carried out to evaluate shear wave velocity Vs to a depth ofaround 30m. Hammer source was used to generate the energy and 12 channel seismographwas used to record the data. Geophone spacing was 3m. Data were recorded when theambient noise was minimum. The collected data are processed using Pickwin software.
Shallow seismic survey was executed at three locations (Fig. 1).
Shear wave velocity study at three locations SS 1, 2 and 3 reveals three velocity layers (Fig. 2,
3 and 4).
Velocity distribution at site SS 1(Fig. 2) is 80m/s, 305m/s and 220m/s for 1st 2nd and 3rdlayers having depth levels at 5m, 15m and 32m respectively.
Velocity distribution at site SS 2 (Fig. 3) is 80m/s, 320m/s and 180m/s for 1st 2nd and 3rdlayers having depth levels at 5m, 15m and 32m respectively.
Velocity distribution at site SS 3 (Fig. 4) is 75m/s, 400m/s and 140m/s for 1st 2nd and 3rdlayers having depth levels at 5m, 15m and 32m respectively.
Shear wave velocity study can be used for the site categorization. Site categories used innational earthquake hazard reduction program (NEHRP) are provided in Table 1.

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Table-1: Site categories in NEHRP provisions (Martin, 1994)
NEHRP Category

Description

Vs 30 (m/s)

A

Hard Rock> 1500B

Firm to hard rock

760 to 1500

C

Dense soil, soft rock360 to 760

D

Stiff soil

180 to 360

E

Soft clays<180

Fig. 2: Shear wave velocity Vs at Station 1

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Fig. 3: Shear wave velocity Vs at Station 2

Fig. 4: Shear wave velocity Vs at Station 3

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PART-V

ANALYSIS OF CLIMATE CHANGE
PHENOMENA IN BANGLADESH

Prepared By
Md. Saidur Rahman
Mehedi Ahmed Ansary

BANGLADESH NETWORK OFFICE FOR URBAN SAFETY(BNUS), BUET, DHAKA

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ABSTRACT
Climate Change has been identified to be the most unanimous topic in the 20th century. Dueto climate change, distribution, frequency and intensity of weather related hazards haveaugmented. In 2008, there were 654 natural disasters worldwide, causing around 93,700
deaths and cost of damage $123 billion. Bangladesh has been vindicated to be one of themost vulnerable countries according to the Global Climate Risk Index. An average of 8,241
people died each year in 244 instances of extreme weather conditions in Bangladesh with costof damage $2,189 million a year and loss of GDP 1.81 percent. Bangladesh is the practicalexample of severely affected by tropical cyclone, flood, drought landslides, and salinity
intrusion as well as other disasters due to climate change. High population density, high levelof poverty, its landscape, geographical position and climate variability has been combined totransform highly vulnerable to natural disaster. According to fourth assessment report (AR4)of Inter governmental Panel on Climate Change, predicted sea level rise from 1990 to 2100 is
18-59 cm. Due to sea level rise saline water intrusion will be up to 150 km in inland area and7-16% of the land will submerge. Proper construction of embankments and polders isimportant for the survival of our existence against imminent natural disasters. The substantial
causes of the embankment failure have not been investigated yet. Forensic research isimperative for investigating such polders. If this research work is implemented, somefacilities like impairment of the saline water intrusion, logistics support for proper disastermanagement, increasing cognizance among the people, reduction of casualties, etc. likely tobe resolved. Otherwise it is not possible to cope with the disaster management under theframework of the climate change risk reduction and mitigation.
1.1 INTRODUCTION
Bangladesh has been recognized as the most vulnerable countries in the world according to
Global Climate Risk Index (CRI index, 2010). Bangladesh is the practical example ofseverely affected by tropical cyclone, flood, Drought landslides, and salinity intrusion as wellas other disasters due to climate change. Due to climate change, distribution, frequency andintensity of weather related hazards have augmented. The country is regularly affected bytropical cyclone because of El Ni o or La Ni a corollary. According to fourth assessment
report (AR4) of IPCC, the increase of sea level has been predicted to be 41 cm from 1990 to
2100. Scientific study has found that global mean daily temperature has increased with a rateof 0.74±0.18°c per 100 years. The sea level is rising at the rate of 3mm per year due to thegradual increase of this temperature. The coastal areas of Bangladesh have been endangered
due to the rising of the storm surges. 150 km inland areas may be affected because of saline
water intrusion. Moreover, 7-16% of the land may be submerged with huge volume of water.
From the past record of cyclone, it has been clear to us that Bangladesh has been confronted
with difficult situation. The people of Bangladesh never forget the cyclone of 1970 and1991.
In 1970, more than 500,000 people died due to the effect of cyclone. After two decades
another cyclone occurred in 1991, at least 138,000 people were killed and 10 million madehomeless following a cyclone in the Chittagong district. The frequency of cyclones can beanalyzed by the recently occurring cyclone Aila and Sidr. About 3,368 people died due to the180163

March 2010

cyclone Sidr in 2007. More than 190 causalities along with huge loss of embankment
occurred due to the cyclone Aila.
There are several thousand kilometers of coastal polders in Bangladesh, which wereconstructed in 1960. Most of the South-Western Coastal polders, which were not designed
properly, have been ravaged by the storm surges. The affliction of people has beenprofligated due to the failure of coastal polders. About 32.4 km entirely and 178.4 km
partially embankments have been damaged by the cyclone Aila (After BWDB, 2009). 153.86
km embankments have been mutilated in the Satkhira Districts (After LGED, 2009). As aresult, proper construction of embankment is essential for our existence against imminent
natural disaster. Otherwise it is not possible to cope with the proper disaster management
under the framework of the climate change risk reduction and mitigation.
1.2 CLIMATE CHANGE SCENARIOS IN WORLDWIDE
Climate change and related global concerns are the most important agenda in the 21st
centuries because of climate variability in all over the world. The atmospheric scientists andenvironmentalist have confirmed the worldwide climate change by increasing the frequencies
of natural disaster. The global Climate Risk Index (2010) analyses to what extent countries
have been affected by the impacts of weather-related loss events (storms, floods, heatwavesetc.) (see Table 1). It is based on past data and is thus not a linear projection of future climate
impacts, also because a single extreme event can not be traced back solely to anthropogenic
climate change The Climate Risk index thus indicates a level of exposure and vulnerability to
extremes events which countries see as a warning signal to prepare for more severe events inthe future. The Intergovernmental Panel on Climate Change (IPCC) predicts that global
temperatures will rise between 1.8°C and 4.0°C by the last decade of the 21st century. The
impacts of global warming on the climate, however, will vary in different regions of theworld.
The IPCC also forecasts that global warming will result in sea level rises of between 0.18 and0.79 meters, which could increase coastal flooding and saline intrusion into aquifer and rivers
across a wide belt in the south of Bangladesh, although most of the area is protected bypolders.
In 2008, there were 654 natural disasters worldwide, causing around 93,700 deaths and costof damage $123 billion. German watchs index estimates that throughout the world, 600,000
people have died in 11,000 cases of natural disasters over the past 10 years. The estimatedglobal financial cost of natural disasters is US $1.7 trillion.
According to the Germanwatch Global Climate Risk Index, Bangladesh, Myanmar and
Honduras were the countries most affected by the extreme weather events from 1990 to 2008
(See Figure1). They are followed by Viet Nam and Nicaragua, Haiti and India. Table 1 andFigure 1 show the ten most affected countries (down 10), with their average ranking (CRI
score) and the specific results in the four indicators analyzed.
Table 1: The most affected 10 countries due to climate change from 1990 to 2008 (After
Global Climate Risk Index, CRI, 2010)

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According to the Germanwatch Global Climate Risk Index, Bangladesh, Myanmar and
Honduras were the countries most affected by the extreme weather events from 1990 to 2008
(See Figure1). They are followed by Viet Nam and Nicaragua, Haiti and India. Table 1 andFigure 1 show the ten most affected countries (down 10), with their average ranking(CRI 48
ICUS Report
score) and the specific results in the four indicators analyzed.
Table 1: The most affected 10 countries due to climate change from 1990 to 2008 (After
Global Climate Risk Index, CRI, 2010)
CRI
19902008
1
2
3
4
5
6
7
8
9
10

Country
Bangladesh
MyanmarHonduras
Viet Nam
Nicaragua
Haiti
India
Dominican Republic
Philippines

China

CRI
score
8.00
8.25
12.00
18.83
21.00
22.83
25.83
27.58
27.67
28.58

Death toll
(Annual ø)
8,241
4,522
340
466
164
335
3,255
222
799
2,023

Deaths per
100,000
inhabitants(Annual ø)
6.27
9.60
5.56
0.64
3.37
4.58
0.33
2.93
1.11
0.17

Total losses
in million
US$ ppp(Annual ø)
2,189
707
660
1,525
211
95
6,132
191
544
25,961

Losses per
GDP in%(Annual ø)
1.81 181
2.55
3.37
1.31
2.03
1.08
0.38
0.45
0.30
0.78

Figure 1: Share of the most extreme year in the overall deaths and losses from 1990-2008 in
the ten most affected countries (After Global Climate Risk Index, CRI, 2010)
All of ten most affected countries (1990-2008) were developing countries in the low-income
or lower-middle income country group. These results underscore the particular vulnerabilityof poor countries to climate risks, despite the fact that the absolute monetary damages aremuch higher in richer countries.

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Table 2: The occurrence of various events in the most extreme years between 1990 and 2008
(After Global Climate Risk Index, CRI, 2010)
SerialNo.

Countries mostaffected from extreme
weather events

Extreme year in total
number of deaths

Extreme year in Total number
total lossesof events

1

Bangladesh

1991

1998

244

2

Myanmar

2008

2008

22

3

Honduras

1998

1998

49

4

Viet Nam

2006

2006

192

5

Nicaragua

1998

1998

34

6

Haiti

2004

2004

40

7

India

1998

1993

325

8

Dominican Republic

1998

1998

39

9

Philippines

1991

2006

243

10

China

1993

2008

558

According to the Climate Risk Index, in 2008 Myanmar, the Republic of Yemen, VietNam
and the Philippines have been most affected by extreme weather events (See Table 2).While
Vietnam and the Philippines are relatively regularly affected through storms and flooding, as
can be seen in the Climate Risk Index editions 2006, 2007 and 2008, the high figures for
Myanmar and Yemen are exceptional. The huge number of fatalities in Myanmar werecaused by cyclone Nargis and revealed the low adaptive capacity of the country which,however, is also a result of the political failure to embark upon serious disaster preparedness.
1.3 CLIMATE CHANGE SCENARIOS IN BANGLADESH
Bangladesh is likely to be among the countries that are the worst affected by climate change.
Tropical cyclones, storm surges, flood, drought and river erosion are likely to become more
frequent and severe in the coming years. According to the Climate Risk Index, Bangladesh
has been identified as the top most affected country due to extreme climate change events(Table 1). In the CRI score Bangladesh got 8, Myanmar 8.25, Honduras 12, Vietnam 18.53,
Nicaragua 21, Haiti 22.83, India 25.83, Dominican Republic 27.58, the Philippines 27.67 andChina 28.58. UNDP has identified Bangladesh to be the most vulnerable country in the world
to tropical cyclones and the sixth most vulnerable country to floods (UNDP, 2004).
Bangladesh is susceptible to floods, tropical cyclones, storm surges, and droughts. The
regions of the country affected by these different hazards are shown in Figure 2.
Most of Bangladesh lies in the delta of three of the largest rivers in the world  theBrahmaputra, the Ganges and the Meghna. These rivers have a combined peak discharge inthe flood season of 180,000 m3 /sec. (the second highest in the world, after the Amazon) andcarry about two billion tones of sediment each year. The topography of the country is mostly
low and flat. Two-thirds of the country is less than 5 meters above sea level and is susceptible
to river and rainwater flooding and, in lower lying coastal areas, to tidal flooding duringstorms (MoFDM, 2009).
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Figure 3:
2: Vulnerability to different natural hazards in Bangladesh (Source: CEGIS, Dhaka)
In the last 25 years, Bangladesh has experienced six severe floods. In 2007, two successive
and damaging floods inundated the country in the same season. During high floods, riverbank erosion is common. It can result in the loss of thousands of hectares of agricultural landand scores of villages, and displace many thousands of people from their homes. Flash floods
can also be a problem in the more hilly north-eastern and south-eastern regions of the country.
Bangladesh has been justified as the most affected countries due to various extreme climatechange events of cyclone, storm surge flood, drought, river erosion, landslides, etc. But inthis paper the climate change phenomena due to tropical cyclone has been stressed. A severe
tropical cyclone hits Bangladesh, on average, every 3 years. These storms generally form in
the months just before and after the monsoon and intensify as they move north over the warm
waters of the Bay of Bengal. The wind speed of the most catastrophic cyclone in Bangladesh
ranges 150 kph to 225 kph and can result in storm surges up to eight metres high, resulting in
extensive damage to houses and high loss of life to humans and livestock in coastal
communities.

Figure 3: Tropical cyclone at different time and Path in Bangladesh (Source: CEGIS, Dhaka).

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The storm surges are higher in Bangladesh than in neighboring countries because the Bay of
Bengal narrows towards the north, where Bangladesh is located. The tropical cyclones in1970 and 1991 are estimated to have killed 500,000 and 140,000 people, respectively. In
recent years, general cyclonic activity in the Bay of Bengal has become more frequent (SeeFigure 43, causing rougher seas that can make it difficult for fishermen and small craft to put
to sea. The climate change scenarios are identified by tropical cyclone like the recently
occurring the super cyclone Sidr in 2007 and the cyclone Aila in 2009.
1.4 HISTORY OF TROPICAL CYCLONES IN BANGLADESH
Tropical cyclone is the most devastating part of climate change phenomena in Bangladesh.
Bangladesh, due to its unique geographic location, suffers from devastating tropical cyclone
frequently. The funnel-shaped northern portion of the Bay of Bengal causes tidal bores when
cyclones make landfall, and thousands of people living in the coastal areas are affected. Someof the most devastating natural disasters in recorded history with high casualties were tropical
cyclones that hit the region now forming Bangladesh.
Table 3: Cyclone events in Bangladesh (After Wikipedia, 2010)168

CycloneYear

Wind Speed,
km/hr

Storm surgeheight, mCasualties

1960

210

4.5-6.1

13,0001961

161

2.44-3.05

11,4681962

161

2.5-3.0

1,000

1963

203

4.3-5.2

11,5201965

201

4.7-6.1

20,152

1966

146

4.7-9.1

850

1970

222

10.6

5,00,000

1974

161

2.8-5.2

800

1983

136

1.52

343

1985

154

3-4.6

11,069

1988

162

4.5

5,708

1991

225

5-8

1,50,000

1994

210

-

400

1995

210

-

650

1997

150

1.83-3.05

126

2007

240

-

>2000

2009

90

3.0

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Among them, the 1970 Bhola Cyclone alone claimed more than 500,000 lives. The
chronological cyclonic events are shown in table 03. In this table record shows the cyclone
year, maximum wind speed, extreme storm surge height and number of causalities. The
scenarios of cyclone Sidr and Aila has been added to analyze the recent trend of cyclone in
Bangladesh.
1.4.1 CYCLONE SIDR IN 2007
The Super cyclone Sidr hit at 9 p.m. on 14 November 2007 about 670 km south of Mongla
port. In Barisal coast the catastrophic of the cyclone Sidr was observed on 15 November at
21:00 hours local time during ebb tide. Wind speeds reached up to 240 km per hour (JTWC)
affecting 15 districts with 15 others partly affected. The tract of the Super cyclone is shownin Figure 3. More than 8.9 million people in 1,950 unions of 200 Upazilas under 30 districts
were affected by Cyclone SIDR. Official reports indicated a total of 3,406 Bangladesh
nationals perished during this event with 1,001 missing and 55,282 sustained physical andpsychological injuries as a result of the disaster. Total damage is estimated to be 1.7
billionUS Dollars.
Total 3,319 people died in 12 affected districts, which is 97% of the total death reported as of
21 January 2008. Highest death toll was reported in Barguna district (1,335) followed by
Bagerhat (810), Patuakhali (457) and Pirojpur (400). The MoFDM Official report indicatesthat 1.75 million families were affected in 12 districts, which is also 84% of the total affectedfamilies in 30 districts. Over 564,967 houses are fully damaged and 957,110 houses are
partially damaged. Bagerhat suffered the most in terms of fully damaged housing (118,899
houses, 22%), followed by Barguna (95,412), Jhalakathi (69685), Pirojpur (63,896) andPatuakhali (53,291).

(a) Erosion of soil(d) Road damage(b) Uprooted trees(e) Death of animals(c) Fracturing of soil(f) Flooding

Figure 4: Some pictures collected from Sidr affected areas in Bangladesh.
A comprehensive analysis undertaken by a team of Bangladesh Government and international
experts, using state of the art assessment methodologies, estimated the total damage andlosses caused by the cyclone to be BDT 115.6 billion (equivalent to US$ 1.7 billion). The
effects of Cyclone SIDR are equivalent to 2.8% of Bangladeshs GDP. The damage and186169

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losses were notably concentrated in the private sector, rather than in the public sector. Thishas significant implications in the strategy that must be adopted for recovery andreconstruction.
Damage and losses were concentrated on the housing sector ($0.83 billion), productive
sectors ($0.48 billion), and on public sector infrastructure ($ 0.25 billion). Most affected
sectors were, in decreasing order, housing, agriculture, transport, water control structures,
education and industry. Some photographs of the cyclone Sidr affected areas in Bangladesh
are shown in Figure 4.
1.4.2 CYCLONE AILA IN 2009
On 25th may in 2009, the cyclone Aila passed through 14 districts in the coastal area of
Bangladesh (See Figure 5). The Aila affected 14 districts were Satkhira, Khulna, Bagerhat,
Barisal, Bhola, Pirojpur, Patuakhali, Borguna, Jhalokathi, Chittagong, Coxs Bazar, Laxipur,
Feni, and Noakhali.

Figure 5: Tropical cyclone Aila (Map courtesy: NOAA)
Loss of life, damages to houses, livestock, crops, educational institutions, roads andembankments have been reported from 529 unions of 64 upazillas of 14districts. Official
sources admitted about 190 deaths and more than 50000 homeless people. Total or partial
destruction of about 6, 12,594 thatched houses, 3, 19,930 hector harvestable paddies, large
number shrimp Gher, 1, 47,628 livestock and poultry. At least 7108 people were injured by
the storm and about 48, 26,630 people were affected.
Mud houses and shrimp production have been damaged by storm surge. In Nizum dwip,
20,000 people are homeless, 58,950 animals are killed and 50,000 deer have been missed.
Storm surge of 3m (10ft) impacted western region of Bangladesh, submerging numerous
villages. More than 400000 people were reportedly isolated by severe flooding in coastal
regions of Bangladesh. Numerous villages were either completely submerged in flood water.
In Patuakhali, a dam broke and submerged five villages. Numerous homes were destroyed by
the subsequent flooding and tens of thousands of people were left stranded in the village.
Coastal polders, which are constructed at the time of 1960, have been damaged by the storm
surge of cyclone Aila. Cyclone Aila damaged 154.72 km embankments in Shyamnagar and

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Assasuni upazillas in Satkhira District of which maintenance and repairing cost is $2.68
million. Moreover, estimated cost for repairing and maintenance of Culvert, Bazar, Union
Parishad Bhaban, Cyclone Shelter, Growth center and Residential Bhaban is $0.5million.
In Satkhira districts cyclone Aila damaged 10 km embankments completely while 120 km
partially where cost for maintenance and reconstruction of these embankments is $3.8 million.
In Khulna district, 211.24km damaged embankment of which 32.4 km fully and 178.84 km
partial damaged $7.75milliom is required for maintenance and reconstruction (See Table 6).
Moreover, for repairing and reconstruction of Sluice gate/regulator, protective work, closure
and other hydraulic structures require $6.96 million (After BWDB, 2009).
1.5 THE COASTAL POLDERS IN BANGLADESH
From the cyclone data of Bangladesh it is common scenarios that over 700 km coastal areasof Bangladesh have been affected by cyclones and storm surges. Bangladesh water
Development Board (BWDB) and its predecessor, East Pakistan Water and Power
Development Authority (EPWAPDA) constructed a series of polders (See Figure 6)
approximately 145 numbers with more than 5,000 km in length in the coastal area from the
mid-sixties to the mid seventies to protect the coastal low lying areas from saline inundationin order to increase agricultural production.

Figure 6: Coastal polders of Bangladesh (After BWDB)Over time, those embankments proved to be very effective in protection of life and property
in the coastal region, rehabilitation or construction of embankments has turned into a crucialpart of coastal development. Historical record shows that more than 14 severe cyclones are
generated in the Bay of Bengal in every ten years, several of which strike the coast of
Bangladesh. Extremely strong storm surges with more than 10m of water elevation hit thecoast of Bangladesh in the Year 1970. Within the last four Decades around 80,000 lives of
the country have been the victims of the cyclones by overtopping or breaching of coastal
embankments. Due to increase the sea level rise the embankments has been damaged due tothe storm surges. The embankments which were affected by the cyclone sidr, have beendamaged by the Cyclone Aila. Bangladesh Water Development Board (BWDB) along with

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other organizations is working together to repair, reconstruct such polders (See Figure 7)
considering the sea level rise and storm surges.

Figure 7: Ongoing project of coastal polders in Bangladesh under BWDB (After IWFM,
2009)
1.6 HISTORY OF EMBANKMENT FAILURE
Although dams have very good safety record, failures do occasionally occur. Such events
always generate a Post-mortem study to determine the cause of failure and to help us avoid
similar events in the future. Studies of dam failures also have provided insight into othergeotechnical problems.
A study by Biswas and Chatterje (1971) examined more than 300 dam failures throughout theworld and found the following causes:
35 percent were a direct result of floods that exceeds the spillway capacity, and thus
were due to inaccurate hydrology.
25 percent were due to geotechnical problems, such as seepage, piping, high porewater pressures, inadequate seepage cutoff, fault movement, excessive settlement, or
landslides.
The remaining 40 percent were from a variety of problems, including the use of poor
construction materials or practices, wave action, acts of war, and poor maintenance.
The most common causes of failure in levees include:
Overtopping by floodwaters, which leads to rapid erosion
Uncontrolled seepage through or breadth the levee, leading to a piping failure
Landslides in the levee slopes
There are a lot of examples of embankment failure in the world. Some histories of crucial
embankment failure are illustrated in Table 4.
All these problems can be avoided through the proper analysis, design, and construction. This
is why modern engineered levees rarely fail. Unfortunately, many miles of unengineered
levees still exist, and the cost of retrofitting or replacing them is enormous. Thus, the primarytask for the geotechnical engineers is to identify the most hazardous ones and reinforce themfirst.
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Table 4: Some Historical embankment failure in the world
Name of dam

Country

Time when failure
occurred
1889

2,209

Overtopping

1928

500

Landslide

France1959

421

Geological failure

Italy
California, USA

1963
1971

2,600
-

Landslide
Liquefaction

Causes of failure

South Fork
Dam
St.
FrancisDam
Malpasset
Dam
Vaiont Dam
Lower
San
Fernando
Dam
BuffaloCreek Dam
Teton Dam

West Virginia, USA

1972

125

Overtopping

Idaho, USA

1976

-

Piping

Levee
USA

New
Orleans
andSoutheast Louisiana

2005

1,118

OvertoppingofJohnstown,
Pennsylvania, USA
California, USA

Causalities

1.7 EMBANKMENT FAILURE IN BANGLADESH
Most of the people living in the southern part of Bangladesh have seen the devastating anddestructive scenarios of cyclone SIDR. But in Cyclone Aila, damage has been increased dueto the breaching of the coastal polders.

Figure 8: Damage of embankment due to the cyclone Aila in Satkhira district by the side of
the Kapatakha river
The authority has to face difficult situation to tackle the effect of Aila. The polders of coastal
belt in Bangladesh have been damaged due to the attack of storm surge. As a result, many
villages have been inundated. Agricultural lands have been severely affected by the intrusionof saline water. Most of the coastal areas were under water. As a result, people could notcommunicate each other due to flooding. Due to breaching of embankments the relief works
have been hampered. Some photographs of Embankment damage from the coastal areas in
Bangladesh after the cyclone Aila are shown in Figure 9.

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1.8 ACTION PLAN FOR UPCOMING CLIMATE CHANGE
In 2005, the GoB has developed the National Adaptation programme of Action (NAPA) after
extensive consultations with communities across the country, professional groups; and othermembers of civil society. The process has been taken forward, including through theadaptation of the Bangladesh Climate change Strategy and action plan (BCCSAP) in 2008,
which is the main basis of Bangladeshs efforts to combat climate change over the next ten
years. The following action plans have been taken to combat the upcoming climate change: Repair and maintenance of existing flood embankments
 Repair and maintenance of existing cyclone shelters
 Repair and maintenance of existing coastal polders
 Adaptation against floods
 Adaptation against future cyclones and storm-surges
 Planning, design and construction of river training works
To mitigate the problem after disaster following suggestion are provided (BCCSAP, 2008).
 Survey of the condition of coastal polders and preparation of GIS maps with present
coverage of areas protected by these polders.
 Repair, reconstruction and maintenance of existing coastal polder based on future projected
sea level rises and storm surges.
 Reconstruction and repair of polders/embankments to design height and section
Specific recommendations due to cyclone Aila:
 Quantify and periodically update the assessment of risk.
 Implement more effective mechanisms for coordination and operation.
 Upgrade engineering design procedures of embankment construction and practice to place
greater emphasis on safety.
 Engage independent experts in high level reviews of all critical life safety structures,
including cyclone and flood protection system.
 Correct the systems deficiencies by establishing mechanisms to incorporate changing
information, making the embankment survivable if overtopped, strengthening the affected
embankment.
1.9 CONCLUSIONS
Although Bangladesh is not responsible for the top most country of GHG emission, someeffective steps have been taken under the Kyoto Protocol. To fight against climate change aswell as tropical cyclone, sustainable infrastructures should be constructed. The coastal
polders, which are fully and partially damaged, may be repaired and reconstructed byappropriate design. Geotechnical investigation of the damaged embankment is required forthe diagnosis of embankment failure as well as proper design. As a result, soil samples ofembankment and foundation may be collected. Without the laboratory test of the soil sample
it should not be possible to control seepage. Design of embankment section may be executed
considering the storm surge height. Proper monitoring is also crucial for stable embankment
construction. The embankment layers may be compacted on the basis of laboratory soil test
data.

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REFERENCES

BNUS (2007). Post Disaster Survey Sidr, Bangladesh Network office for urban safety,
Bangladesh University of Engineering and Technology (BUET), Dhaka, Bangladesh.
BWDB (2009). Preliminary Assessment of Bangladesh Water Development Board
Infrastructure in Coastal Area of Bangladesh, Bangladesh Water Development Board,
July, 2009.
ITHACA (2009). Bangladesh-Tropical Cyclone Aila. Areas affected with surface water as of
May 27th, 2009, Information Technology for Humanitarian Assistance, Co-operation andAction. Accessible at: www.ithaca.polito.it/maps.php.
Kabir M. M., Saha B. C, Hye J. M. A, 2007. Cyclonic Storm Surge Modelling for Design of
Coastal Polder. Institute of Water Modelling, Dhaka, Bangladesh. Available at:
http://www.iwmbd.org/html/PUBS/publications/P024.PDF.
LGED (2009). List of Affected/Damaged Infrastructure by Recent Cyclone Aila on 25-052009, Local Government and Engineering Division, July, 2009.
MoEF (2005). National Adaptation Programme of Action (NAPA). Ministry of Environment
and Forests, Government of the Peoples Republic of Bangladesh, Dhaka, Bangladesh.
MoEF (2008). Bangladesh Climate Change Strategy and Action Plan 2008. Ministry ofEnvironment and Forests, government of the Peoples Republic of Bangladesh, Dhaka,Bangladesh.
MoFDM (2009). Tropical cyclone Aila areas Affected with Surface Water, Ministry of Foodand Disaster Management, Dhaka, Bangladesh June, 2009.
Mohal Nasreen, Khan Zahirul Haque, Rahman Nazibur, 2006. Impact of Sea Level Rise on
Coastal Rivers of Bangladesh. Coast, Port &Estuary Division, Institute of Water
Modelling(IWM),
Bangladesh.
Availableat:
http://www.riversymposium.com/2006/index.php?element=06MOHALNasreen.
NOAA (2009). Tropical cyclone Aila, Website: www. reliefweb. Int /rw/
fullMaps_Sa.nsf/luFullMap.
Sven Harmeling, 2010.Global Climate Risk Index. Who is most vulnerable? Weather-related
loss events since 1990 and how Copenhagen needs to respond. Available at:
http://www.germanwatch.org/klima/cri2010.pdf.
UNDP (2004). A challenge for Development, A Global Report on Reducing Disaster Risk.
Accessibe at: www. undp. org/cpr/ we_do/integrating risk. shtml).
Wikipedia (2010). List of Bangladesh tropical cyclones. Available at:
http://en.wikipedia.org/wiki/List_of_Bangladesh_tropical_cyclones (Accessed on 29th
January, 2010).

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WORKSHOPS, SEMINARS AND MEETINGS

Prepared By
Md. Saidur Rahman
Sharmin Ara
Mehedi Ahmed Ansary

BANGLADESH NETWORK OFFICE FOR URBAN SAFETY(BNUS), BUET, DHAKA

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SAARC Training Course on
EARTHQUAKE RISK MITIGATIONMarch 30-April 4, 2009
At Centre for Continued Education, IIT Roorkee, Roorkee
Organised by
SAARC Disaster Management Centre, New Delhi, and Centre of Excellence inDisaster Mitigation Management, IIT Roorkee
BNUS members Ms. Afifa Imtiaz, Ms. Israt Jahan and Mr. Yusuf Reza
participated.

Group Photo of SAARC training program at IIT, Roorke

Paper Presentation of Afifa Imteaz

Inaugural session of the program
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Participants of the Training

Taking certificate and crest

SAARC Training Program on
CLIMATE CHANGE ADAPTATION AND DISASTER RISKREDUCTION IN SOUTH ASIA
July 9-July 15, 2009
Inaugural session: Senate Hall auditorium, University of Dhaka
Training Sessions: Centre of Excellence, 2nd Floor Lecture RoomThe Dean of the Faculty of Earth and Environmental sciences, university of Dhaka and the
SAARC Disaster Management Centre, New Delhi arranged the seven days SAARC Training
on Climate Change Adaptation and disaster Risk Reduction in South Asia from July 9 to July
15, 2009. The purpose of this workshop is to share the knowledge about the climate change
phenomena south Asian countries. The sustainable solution of climate change Adaptation andDisaster Risk Reduction have been dicussed. We, three stuff of BNUS (Israt Jahan Sheuly,
Md. Saidur Rahman, Salahuddin Rizvi), participated the seven days Training course from
July 8 to July 15. This course is very significant for our capacity build up along with analysis
the climate change Phenomena in the South Asian Countries. In this course Dr. Shahnaz
Hussain co-ordinated and Dr. Amanat Ullah Khan was the moderator. The various Topics on
Climate Change this course have been presented by the Climate Change expert in Bangladesh
and other countries. The Causes of Climate change along with the adaptation and the Risk
Reduction through sustainable solution have been discussed. There was open discussion
session for pointing out the current problem and their possibility of solution. From open
discussion it has been noticed that every country having some different problem of climatechange. Bangladesh and Myanmar is severely affected by the Cyclone and flood. Pakistan,
Nepal, India and Bhutan are vulnerable severely due to landslide. Maldives is vulnerable dueto the Sea level Rise and inundation. Drought is common to every country in South Asia.
Myanmar is also severely affected by the cyclone. Drough and Landslides are big problem in
Srilanka. The following topics have been discussed on the course:
Climate change and growing vulnerability of Natural Disaster in South Asia
Global Climate Change scenario

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Climate Change projection in South Asia by IPCC
Critical Climate change issues and associated disaster in South Asia
Global Disaster Trends
Climate change impact in Agriculture and Food Security
Climate change impact in water resources
Climate change impact in different communities
Linking climate change adaptation and disaster risk reduction
Tacking Global Climate Change: Challenges of Regional and International Cooperation and
Networking
Adaptation of regional Climate models in generating climate change scenarios
Climate change adaptation in south Asia
Adaptation and Disaster Risk reduction in South Asia: Bridging gaps between communities
and climate change issues
Funding for Climate Change Adaptation
Sustainable development in a changing Climate Change
Climate Change and coastal Ecosystem
Impact of Climate Change on Sea level rise in Bangladesh
A few aspects of climate change, impacts and adaptation in Bangladesh
Climate Change impacts in agriculture
Climate change impact in Human Health
Structural Strengthening of Houses and Infrastructure
Tools, Techniques, and Practices for integration of Disaster Risk Reduction into Climate
Change Adaptation
Adapting to flood and Risks-case studies
Adaptation to Cyclone Risk-case studies
Mindset Change for adaptation to Climate Change in Bangladesh
Adaptation to GLOF-Case Studies
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Climate Change implication on Forest and Biodiversity
Adaptation To coastal Erosion
Good Climate Change Adaptation practices in Bangladesh
Climate change Knowledge enhancement in Disaster Risk Reduction
Geo-Hazard data and information available to response the climate change
Gender Dimension in Disaster management adjusting with Floods & Cyclones

Eight SAARC countries of the program

Presentation of the program

Participants of the program

SAARC participants with BNUS staff

Taking Certificate from the Honorable Minister, Dr. Muhammad Abdur Razzaque , Ministryof Food and Disaster Management.
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Two young researchers with Dr. Amanat Ullah Khan

WORKSHOP ON
Disaster Risk Reduction through Schools
National Convention-2009
August 3-August 4, 2009
At National Museum and Public Library
Session-1: People Assembly: Voice from the Grass roots
Session-2: Interactive Session
Video presentation; Cyclone Sidr and the Disaster Preparedness of Students
The Culture of Disaster Risk Reduction and Resilient through the Eyes of ChildrenModerator: M A Al-Mamun Mazumdar, Project Manager, Sap Bangladseh
Session-3:
National Consultation on Integrating Disaster Risk Reduction and Climate Change
Education in National Policy Vision
Session-4:
Video Presentation-Lamias StoryDescribing Grassroots Reality:
Presentation on the summary of the National consultation
Parallel Programmes:
Exhibition on the Publication and materials on Disaster Risk reduction- Public Library

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Photography and Exhibition on paintings by the children
Two days long Film festival (Documentary Feature film Presentation on Disaster and Climatechange)-Central Public Library
Session-5: Life Experience in Disaster Preperedness
Session-6: Natonal consultation on Disaster Resilient and Climate Literate Future
Generation
Session-7:
Documentary Lamias StoryPolicy Convergence in the light of grassroots experienceThe implication of Mass Media in Disaster Risk

Some pictures from the workshop

Regional Workshop on Reducing Earthquake Risk throughComprehensive Preparedness and Mitigation planning
December 10 -12, 2009
BNUS Director Prof. Mehedi Ahmed Ansary and all BNUS members participated in thisworkshop and worked as Rapporteurs for different sessions.
ERRP Regional Program in collaboration with Disaster Management Bureau, Government of
Bangladesh, SAARC-DMC, ADRC and WSSI has organized 3 day long (December 10 -12,2009) Regional Workshop on Reducing Earthquake Risk through Comprehensive
Preparedness and Mitigation planning (Lessons and recommendation in context of SouthAsia)”

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The program has been successfully inaugurated on the scheduled day. The welcome speech
was given by Mr. Sohel Khan and was followed by Dr. D. D. Joshi from SAARC Disaster
Management Center (SDMC). Mr. Khan gave a brief on ERRP (Earthquake Risk Reduction
and Recovery Program) thats: ERRP (Earthquake Risk Reduction and Recovery Program)covers five countries: Bangladesh, Bhutan, India, Pakistan and Nepal with the main
objectives of exchange of information, experience sharing and sharing of knowledge and wasstarted in 2008 by UNDP with the support of Japan. Dr. Joshi introduced SDMC, its
objectives and activities in disaster management.
Mr. Koresawa, Executive Director, ADRC also gave the opening address

discussing on

main objective of the center, its recent activities with findings and its future initiatives. He
declared on the upcoming disaster risk reduction conference in Kobe Japan, from 17-19,
January 2010.
The special guest chairs were honored by Mr. Stefan Priesner, Country Director, UNDP
Bangladesh and H.E. Mr. Tamotsu Shinotsuka, Ambassador, Embassy of Japan in
Bangladesh. Mr. Priesner addressed Bangladesh as a leader in DRR and other countries learn
the Disaster Management Techniques from here.
Mr. Dipankar Talukder, state minister, CHT Affairs, GoB was the guest of honor and herecommended laws and by laws must be relevant and govt. agencies must be strengthened to
enforce the implement of law.
Finally Dr. Md. Abdur Razzak, Minister, MoFDM, Govt. of Bangladesh honorable chief
guest discussed on the disaster scenario in South-Asia and officially inaugurated theworkshop.
Researcher of BNUS (Israt Janan Sheuly, Md. Saidur Rahman, Ripon Hore) were got theopportunity to participate in this two day long workshop. They also act as rapporteur of theworkshop.
TECHNICAL SESSION
The technical session was chaired by Mr. Shankar Prashad Koirala, Joint Secretary,
Ministry of Home affairs, Govt. of Nepal.
In this session Dr. D.D. Joshi of SDMC elucidates and rendered an excellent
presentation on Earthquake Risk and Vulnerability in South Asia.
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CASE STUDY PRESENTATION
After that some case studies were presented.
At first Earthquake Risk Reduction Initiatives Particular focuses on Preparedness andResponse Planning by Mr. Maksud Kamal, CDMP, GoB and UNDP.
Then Post 2005 Earthquake Experience (Recovery and Preparedness): Incorporating
Risk Reduction in Planning by Mr. Tariq Rafique, Pakistan
Lessons from the Reconstruction of Houses in Aech after the December 26, 2004
Tsunami by Mr. Teddy Boen, Senior Advisor, WSSI.
COUNTRY REPRESENTATIONSCountry Representations on Experience and lessons of ERRP at the country level weredone for Bangladesh, Bhutan, Nepal and Pakistan by the respective country representative.
GROUP DISCUSSION
The participants in the workshop were distributed into 3 Groups to participate in group
discussion on three major issues.
Group 1 discussed on Strengthening of city/ municipality planning, implementation ofeffective ERR, which was chaired by Mr. Farhad Uddin, Director General, DMB, GoB andModerated by Prof. Dr. Mehedi Ahmed Ansary, Director,WSSI.
Three case studies have been presented there.
Mr. Yoshihiro Imai, ADRC presented on Disaster Prevention in Japan and City
Planning.
Mr. Suraya Shrestha, NEST, ADPC presented on Efforts and lessons of Urban
Earthquake Risk Management in Nepal
Mr. Anisur Rahman, ADPC presented on Measures for Strengthening of City Level
Planning for Effective implementation of ERRP: a case study of Bangladesh.
Group 2 discussed on Financing for sustainable Earthquake Risk Reduction and
Mitigation at pre and post disaster stage, chaired by Mr. Md. Abdul Wazed, Joint
Secretary, MoFDM, GoB and moderated by Mr. Vijaya Singh, ARR, UNDP-Nepal.

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Three case studies have been presented there.
Earthquake Insurance in Japan - Strong tool for Risk

Management by

Yoshiaki Ogane, Senior Researcher, ADRC
Financing for Sustainable Disaster Risk Reduction in Pakistan by Raja Sajjad
Khan, Director, State Disaster Management Authority, Azad Jammu & Kashmir
Financing for sustainable Earthquake Risk Reduction and Response by
Mohammad Abu Sadeque, Deputy Secretary, MoFDM
Group 3 discussed on Monitoring and Evaluation of ERR initiatives at the national andregional level, chaired by Mr. Phuntsho Wangdi, Director, SQCA, Ministry of Works andHuman Settlement, Govt of Bhutan and moderated by N.M.S.I Arambepola, Director,
UDRM, ADPC.
Two case studies have been presented there
Yuki Matsuka, UNSIDR presented on Monitoring and Evaluation of ERR
initiatives: HFA Monitor System and Indicators.
N.M.S.I Arambepola, Director, UDRM, ADPC presented on Monitoring &Evaluation of ERR initiatives at City/municipality levels and Regional/National
levels.
With the group discussions in three different parallel sessions the day 1 activities weresuccessfully concluded and the outcomes from group discussions were presented on the nextday.
The second day introduced with the Group presentation on the recommendations found fromof first day group discussion by the group leaders.
Recommendations from Group1
Involvement of local authorities in implementation of ERR through city plannig
Earthquake risk assessment should conclude with earthquake risk reduction.
All municipalities should have upgraded master plan considering ERR
Exchange of information among the municipal authorities
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City authorities should consider liquefaction susceptible zones in land use planning.
Recommendations from Group 2
Investment in DRR has to be increased
Capacity for DRM (Disaster Risk Management) planning for national, local andregional level has to be increased
Ensure Sustainability of DRM financing. (out side government financing)
Insurance for ERR need to be explored and confirmed. (high rise building, privatecompanies etc)
Strengthening Existing Environment Impact Assessment Process (DRR Sensitive).
Development of DRM National Action Plan.
Recommendations from Group 3Group 3 strongly & unanimously recommends the current Forum to request Regional
Office for ERRP, to organize a Regional Meeting of National Project Managers
responsible for the implementation of National ERRP, to draw up appropriate nationaland regional indicators to measure progress of ERR initiatives closely following theprinciples and features HFA template indicators.
National Governments to take an active lead Roles to ensure that indicators developed
within their ERR framework for measuring national ERR initiatives are resolutely
adopted and enforced. To ensure that progress on ERR initiatives are effectively(honestly) measured against adopted indicators by the government, civil societies /NGOs will be empowered to check / scrutinize to authenticity of such actions taken.
At the regional level, a central agency such as SDMC will be mandated to coordinate
the collection and review of nationally adopted indicators and arrange a vote for
acceptance by other member states / nations before the indicator/s in the subject canbe accepted as a regional indicator.
PRESENTATIONS

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Afterward Teddy Boen presents on Vulnerability of Non-engineered masonry houses andcommon retrofitting practices for preparedness (reference to South and South East
Asia).
Then Mr. Hiroshi Imai gave a presentation on Retrofitting of Vulnerable Structure: Case
analysis of Pull down Experiment to review the seismic performance of existing
masonry building held in Nepal and Mr. Masato Ohori, ADRC commented on the pull
down demonstration.
Then Dr. D.D. Joshi of SDMC renders a presentation on Report on the Digital
Vulnerability Atlas project.
Mr. Sohel Khan presented on Review of Call for action recommended in ERRP
Conference in India and proposed next steps.
Formation of Community based Urban Volunteers by Major Motiur Rahman, Director,
Training and Planning, Bangladesh Fire Service and Civil Defense.
PANEL DISCUSSION
The last session of the workshop was Panel discussion of experts on Mainstreaming of ERR
into Development Planning.
PHOTOGRAPHS OF ERRP WORKSHOP AT HOTEL LAKE SHORE

Photo1: Inauguration Session of the Workshop

Photo2: Posters Displayed at the Workshop

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Photo3:
Photo3:
Dr. Dr.
MehediMehedi
Ahmed
Ahmed
AnsaryAnsaryat theat theWorkshopWorkshop

Photo4:
Photo4:
Participators
Participatorsof theof theERRP
ERRP
WorkshopWorkshop

Photo
Photo
5: Researcher
5: Researcher
of BNUSof BNUS

Photo
Photo
6: Teddy
6: Teddy
Boen
Boen
GivingGivingPresentation
Presentation
on on
Vulnerability
Vulnerabilityof Non-Engineeredof Non-Engineered
Building
Building

Photo
Photo
7: One7: Oneof theof theParticipantsParticipants
Presenting
Presenting
Group
Group
Discussion
Discussion
on Selected
on Selected
Topic
Topic

188

Photo
Photo
8: Panel
8: Panel
Discussion
Discussionof theof theWorkshopWorkshop

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Visit of Dr. Shinji Tanaka at Bangladesh Network Office for Urban Safety(BNUS)
Dr. Shinji Tanaka from Transportation Engineering division of Asian Institute of Technology(AIT), Thailand, visited Bangladesh Network Office for Urban Safety (BNUS), BUET, Dhaka
on 7 December, 2009. Dr. Mofiuzur Rahman of Department of Civil Engineering, BUET
accompanied him. Prof. M. A. Ansary (Director, BNUS) briefed on various Research works
and BNUS activities which were executed at different times. BNUS researchers Ms. Israt
Jahan and Md. Saidur Rahman assisted Professor Ansary in explaining the tasks completed
by BNUS.

Group Photos with Dr. M.A.
Ansary, Dr. Shinji Tanaka andDr. Mafuzur Rahman

Dr. M.A. Ansary representing
the BNUS activities

A gift presented to Dr. Shinji
Tanaka by Prof. M.A. Ansary

Prof. Dr. M. A. ansary demonstrated briefly the Earthquake Evacuation Plan for Old Dhaka,
Microzonation Map of Cox’s Bazar city, Earthquake Recording Instruments at various
locations in Bangladesh, The occurrence of cyclone (Sidr and Aila) and Climate Change
Scenarios in Bangladesh and so on. He also showed interest for research in transportation
sector. Dr. Tanaka appreciated the performed activities and inspired for further efficientcurriculum in future. Finally, Dr. Ansary presented a gift to Dr. Shinji Tanaka for visiting to
BNUS office in Bangladesh University of Engineering and Technogy (BUET).

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One Day Workshop on Fire Hazard in Bangladesh and Remedial Measures
February 10, 2010
Held at ITN Centre, BUET
Organizers: Tokyo University of Science, Japan, Bangladesh Fire Service and BNUS, BUET
Some Photographs and Participant list is attached.

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