seismic zonation map of bangladesh. - indico...

Seismic Seismic ZonationZonation Map of Map of BangladeshBangladesh

Mehedi Ahmed AnsaryMember Steering CommitteeMember Steering Committee

Bangladesh National Building CodeBangladesh National Building Code&

Bangladesh Earthquake Society(BES)

Department of Civil Engineering BUETDepartment of Civil Engineering BUET

Active Faults Surrounding Bangladesh (Active Faults Surrounding Bangladesh (Bolt, 1985Bolt, 1985))

BOGRA FAULT BOGRA FAULT SYSTEMSYSTEM

SYLHET FAULT SYLHET FAULT SYSTEMSYSTEM

TRIPURA FAULT TRIPURA FAULT SYSTEMSYSTEM

DAUKI FAULT DAUKI FAULT SYSTEMSYSTEM

DHUBRI FAULT DHUBRI FAULT SYSTEMSYSTEM

Dhaka

CHITTAGONG CHITTAGONG FAULT SYSTEMFAULT SYSTEM

19931979

EARTHQUAKE HAZARD EARTHQUAKE HAZARD ANALYSISANALYSIS

Earthquake CatalogueEarthquake Catalogue

�� An earthquake catalogue forms a valuable input for seismic An earthquake catalogue forms a valuable input for seismic hazard assessment and hazard assessment and microzonationmicrozonation studies. studies.

�� Critical structures such as nuclear power plants and dams, Critical structures such as nuclear power plants and dams, as well as siting of any new industry, require earthquake as well as siting of any new industry, require earthquake data that are accurate, homogeneous and as complete as data that are accurate, homogeneous and as complete as possible.possible.

�� In this study an attempt is made to assess the In this study an attempt is made to assess the seismicityseismicity of of Bangladesh and adjoining region (Bangladesh and adjoining region (2020--282800 north latitude and north latitude and 8686--959500 east longitude) during the period east longitude) during the period 18651865--19951995 by by reviewing instrumental data as well as macroseismic reviewing instrumental data as well as macroseismic information retrieved from various sources.information retrieved from various sources.

1865-2003

Existing Existing Earthquake Earthquake CatalogueCatalogue

Revision of MagnitudesRevision of Magnitudes�� The idea of revising and unifying existing magnitudes is The idea of revising and unifying existing magnitudes is

carried out. The main goal is to produce a file of reliable carried out. The main goal is to produce a file of reliable data that reflect, as homogeneously and completely as data that reflect, as homogeneously and completely as possible, the possible, the seismicityseismicity of the region.of the region.

Calculation of surface wave magnitude:Calculation of surface wave magnitude:

Ms= log(A/T)+1.66 logMs= log(A/T)+1.66 log∇∇+3.3+3.3

Use of correlations:Use of correlations:

�� SurfaceSurface--wave magnitudes are estimated where possible wave magnitudes are estimated where possible from semifrom semi--empirical relationships between Mempirical relationships between Mss and Mand Mbb. .

MMss = a + b*M= a + b*Mbb..

Ms = 0.63+0.774*Mb Ms = 0.63+0.774*Mb -- period 1978period 1978--19951995

Ms = 1.27+0.68*Mb Ms = 1.27+0.68*Mb -- period 1964period 1964--19771977

�� SurfaceSurface--wave magnitudes are also assessed by using the wave magnitudes are also assessed by using the number of stations (NS) that reported it to the ISS or ISC. number of stations (NS) that reported it to the ISS or ISC.

Ms = a + b* Log (NS)Ms = a + b* Log (NS)

a =4.21, b=1.12 a =4.21, b=1.12 -- period 1900period 1900--19631963



�� SurfaceSurface--wave magnitudes are also estimated where possible wave magnitudes are also estimated where possible from semifrom semi--empirical relationships between Mempirical relationships between Mss and Duration and Duration Magnitude MMagnitude Mdd. .

MMss = 0.57+1.057*= 0.57+1.057*MMdd -- period 1993period 1993--19951995

4.0 4.5 5.0 5.5 6.0 6.5

3.5

4.0

4.5

5.0

5.5

6.0

6.5

Ms Vs Mb (1978-1995)s

M s(I

SC

)

Mb

s

3.5 4.0 4.5 5.0 5.5 6.0 6.53.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5Ms Vs Mb (1964-1977)

s

M s(C

alcu

late

d)

Mb

YR MNH DY H MIN S LON LAT DEP Ms Mb Md M Ml Mw ITSC NS RMK LOCATION REFERENCES1964 1 22 15 58 47 9360 2240 88 544 ( ) 610 - 600 - - - 153 - MR-ID ROT,ISC,MOS,SHL,USCGS,IS1964 2 1 11 28 19 8778 2730 33 442 ( ) 480 - - - - - 20 - NP ISC,USCGS,ISETR1964 2 18 3 48 36 9110 2750 30* 449 ( ) 530 - 560 - - - 67 - BU ROT,ISC,MOS,USCGS,TS,ISE1964 2 18 4 26 34 9430 2500 - - - - 540 - - - - - - TS1964 2 27 15 10 48 9440 2170 102 545 ( ) 640 - 650 - - - 212 - Mandalay.MR ROT,ISC,MOS,SHL,USCGS,IS1964 3 20 19 0 53 9440 2360 86 465 ( ) 500 - 560 - - - 52 - MR-ID ROT,ISC,MOS,SHL,USCGS,IS1964 3 27 23 3 42 8930 2720 29 456 ( ) 500 - - - - - 46 - BU ROT,ISC,MOS,USCGS,GS,IS1964 4 13 3 20 5 9020 2760 52* 473 ( ) 520 - 600 - - - 53 - BU ROT,ISC,MOS,USCGS,ISETR1964 4 15 16 35 58 8800 2170 36* 468 ( ) 520 - 560 - - 7 80 - Calcutta.ID ROT,ISC,QUE,MOS,USCGS,S1964 6 3 9500 2600 - MR-ID ISETR1964 6 9 12 33 22 8790 2150 0 390 [1] - - - - - - 9 - ID ISC,SHL1964 6 13 17 35 58 9400 2300 61 449 ( ) 520 - 600 - - - 108 - MR-ID ROT,ISC,MOS,USCGS,SHL,IS1964 7 12 9450 2700 - Sagaing.MR ISETR1964 7 13 10 58 48 9470 2370 117 492 ( ) 540 - 600 - - - 138 - MR-ID ROT,ISC,USCGS,MOS,SHL,G1964 8 17 14 42 54 9418 2432 158 438 ( ) 480 - - - - - 24 - MR-ID ISC,USCGS,ISETR1964 8 30 2 35 8 8830 2760 21 456 ( ) 510 - 560 - - - 78 - Sikkim.BU ROT,ISC,SHL,MOS,USCGS,T1964 8 30 5 12 32 8852 2790 33 377 [1] - - - - - - 6 A Sikkim .BU ISC,ISETR1964 9 1 13 22 37 9230 2720 33 472 ( ) 550 - 600 630 - - 148 - ID-CH ROT,ISC,SHL,USCGS,MOS,T1964 10 4 20 55 38 9440 2600 - 372 [1] - - - - - - 5 - MR-ID NDI,ISETR1964 10 6 2 55 0 9450 2790 413 422 ( ) 450* - - - - - 11 - E.ID ISC,USCGS,ISETR1964 10 13 10 36 56 9120 2400 - 399 [1] - - - - - - 12 - ID-BD ISC,NDI,ISETR1964 10 21 9370 2800 37 - 590 ID-CH ISETR1964 10 25 15 40 7 8860 2790 0 434 ( ) - - - - - - 9 - Sikkim ISC,NDI,ISETR1964 12 1 15 10 24 9446 2118 104 390 [1] - - - - - - 9 - MR ISC,ISETR1965 1 12 13 32 24 8800 2760 23 529 ( ) 580 - 650 - - - 151 - NP ROT,ISC,PEK,QUE,USCGS,S1965 1 12 13 55 20 8770 2730 33* 454 ( ) 520 - 560 - - - 52 - NP ROT,ISC,PEK,USCGS,ISETR1965 1 18 8 17 38 9380 2500 - - - - 590 - - - - - - PAPER1965 1 22 2 41 35 9450 2010 76 454 [2] 480 - 560 - - - 37 - MR-CH ROT,ISC,ISETR1965 2 18 4 26 34 9430 2500 36 479 ( ) 540 - 600 - - - 122 - ID-CH ROT,ISC,ISETR1965 2 25 10 34 7 9464 2363 94 471 ( ) 520 - - - - - 98 - MR-ID ISC,PEK,USCGS,MOS,SHL1965 3 27 20 45 51 8990 2730 33 360 [1] - - - - - - 7 - BU ISC1965 4 11 22 33 7 9233 2682 70 465 ( ) 490 - 510 - - - 50 - E.ID ISC,USCGS,TS,ISETR1965 6 1 4 32 45 9490 2020 57 477 ( ) 520 - 600 - - - 124 - MR;MR-CH ROT,ISC,GS1965 6 18 8 17 38 9380 2500 46 464 ( ) 520 - 600 680 - - 105 - MR-ID;ID-CH (Arakan YoROT,ISC,GS,TS,ISETR1965 7 5 23 41 39 9480 2120 65* 427 [2] 440 - - - - - 29 - MR ISC,USCGS,NDI,ISETR1965 8 4 15 27 1 8830 2350 - 343 [2] - - - - - - 2 - ID-BD NDI1965 9 30 8 48 27 9400 2500 - 356 [2] - - - - - - 3 - MR-ID NDI1965 11 6 16 4 59 9170 2710 40 404 ( ) 430 - - - - - 9 - BU USCGS1965 11 6 9160 2720 33 - 480 BU ISETR1965 12 5 22 1 28 9450 2330 13 467 ( ) 500 - 560 - - - 82 - MR-ID ROT,ISC,USCGS,ISETR1965 12 9 20 26 4 9250 2750 22 478 ( ) 520 - 560 - - - 86 - ID-CH ROT,ISC,PEK,USCGS,TS,ISE

New Earthquake Catalogue

Earthquakes in and around Bangladesh (1664Earthquakes in and around Bangladesh (1664--2006)2006)

0 100

kilometers200

98°E84°E

31°N

18°N

Ms>4: 1647 events

Ms>3.5: 3055 events

Ms>3: 4138 events

Ms>7: 17 events

Ms>6: 69 events

Results from Analysis of Completeness Results from Analysis of Completeness for the New Earthquake Cataloguefor the New Earthquake Catalogue

Magnitude ClassMagnitude Class Period of Complete Reporting (year)Period of Complete Reporting (year)

33≤≤M<4M<4 19641964--20062006

44≤≤M<5M<5 19641964--20062006

55≤≤M<6M<6 19231923--20062006

66≤≤M<7M<7 19271927--20062006

77≤≤MM 18651865--20062006

Selection of earthquakes

Location of site

Data period (based oncompleteness)Minimum MagnitudeRadius of Area

Selection of suitable radiusEarthquake catalogue

Map of epicenters

Magnitude frequencyrelationship

Estimation of a and bparameters

Selection of groundmotion property to beanalyzed (PGA)

Expected magnitude fordifferent return period

PGA frequencyrelationship

Selection of suitableattenuation law

Estimation of a and bparameter

Expected PGA fordifferent returnperiods

Expected returnperiod for a fixedPGA value

Schematic flow of earthquake hazard analysis

SeismicitySeismicity model: model:

�� Available earthquake dataAvailable earthquake data

�� Recurrence relationshipRecurrence relationship

log (log (νν)) = = a + a + blog(yblog(y))

log(y)log(y) ==((--log(T)log(T)-- a)/ba)/b [T=1/[T=1/νν]]

Attenuation models:Attenuation models:

describes the transfer of ground motions from the describes the transfer of ground motions from the source to a particular site in the formsource to a particular site in the form

log(PGA) = blog(PGA) = b1 1 + b+ b2 2 (M(Mss) ) -- bb3 3 log (r) log (r) -- bb4 4 (r)(r)

Selected Attenuation LawSelected Attenuation Law��Assessment of seismic hazard at any particular site Assessment of seismic hazard at any particular site

requires an attenuation law for the Peak Ground requires an attenuation law for the Peak Ground Acceleration (PGA) Acceleration (PGA)

�� For Bangladesh no PGA is available due to the lack For Bangladesh no PGA is available due to the lack of seismic devices of seismic devices

�� Attenuation law for alluvial soils:Attenuation law for alluvial soils:McGuireMcGuire (1978) (1978) -- PGA=0.0306ePGA=0.0306e0.89M0.89Mrr--1.171.17ee--0.2 0.2 (in g)(in g)DuggalDuggal (1989)(1989) -- PGAPGA=227.3x10=227.3x100.308M0.308M(d+30)(d+30)--1.2011.201 (in cm/s(in cm/s22))

50 100 150 200 250 300 350 400 450-1.0

-0.8

-0.6

-0.4

-0.2

0.0

Sylhet Chittagong Dhaka

b co

effic

ient

Radius (km)

1 10 100 10001E-3

0.01

0.1

1

10

Mea

n A

nnua

l Occ

urre

nce

Rat

e (ν

)

PGA (cm/s2)

SELECTION OF EARTHQUAKES AROUND A SITE

Sensitivity of b-coefficient PGA versus ν for Sylhet

a=1.92b=-1.72

PGA

ν

Radius

b

Study region Study region showing the showing the grid pointsgrid points

86 88 90 92 9420

22

24

26

28

Chittagong

Dhaka

Sylhet

BAY OF BENGAL

BANGLADESH

BURMA

INDIA

INDIA

BHUTANNEPAL

LAT

ITU

DE

LONGITUDE

Seismic hazard of Bangladesh based on Duggal’s (1989) attenuation law

T = 200 years(Unit: cm/s/s)

45037530022515075

22% 22% poepoe, t, t--50 yr50 yr

T = 475 years(Unit: cm/s/s)

900750600450300150

10% 10% poepoe, t, t--50 yr50 yr

AfterAfter NoorNoor, , YasinYasin & & AnsaryAnsary (2005)(2005)

•Grid interval of 0.3 degree are used•Uniform probability distributions are assigned to each source zone implying that, earthquakes are equally likely to occur at any point within the source zone•Seven area sources are assumed•The sources are so divided that area of each division is limited to 1200 sq km

.

Seismic hazard of Bangladesh based on Duggal’s (1989) attenuation law

22% 22% poepoe, t, t--50 yr50 yr 10% 10% poepoe, t, t--50 yr50 yr

AfterAfter NoorNoor, , YasinYasin & & AnsaryAnsary (2005)(2005)

Seismic Zoning Map of Bangladesh

BNBC (1993)

Seismic Zones

Zone 3 = 0.25g

Zone 2 = 0.15g

Zone 1 = 0.075g

Proposed

Development of Development of Attenuation LawAttenuation Law

MagnitudeMagnitude--Intensity & Intensity AttenuationIntensity & Intensity Attenuation

Data Preparation:Data Preparation:��The average radius of each isoseismal was The average radius of each isoseismal was

determined from the radii measured in 16 determined from the radii measured in 16 directions at 22.5directions at 22.500 intervals of the compass intervals of the compass

�� IsoseismalsIsoseismals with no reliable data were disregarded with no reliable data were disregarded from the regression analysisfrom the regression analysis

��The description of the 18 earthquakes used in this The description of the 18 earthquakes used in this study is presented in the following tablestudy is presented in the following table

Area under study and locations of 28 eventsArea under study and locations of 28 events

85 86 87 88 89 90 91 92 93 94 95 96 9718

19

20

21

22

23

24

25

26

27

28

29

30

28

2627

25

23

24

21

19

22

20

1

17

186

5 10

14

13

16

12

2

7

4

3

15

8

9

11

BAY OF BENGAL

BANGLADESH

MYANMAR

INDIA

INDIABHUTANNEPALLA

TIT

UD

E

LONGITUDE

MagnitudeMagnitude--IntensityIntensity

Magnitude Intensity Model:Magnitude Intensity Model:

Msc = A1 + A2(Ii) + A3(Ri) + A4logRi + σP

Bangladesh and its surrounding region, which consists of 25 evenBangladesh and its surrounding region, which consists of 25 events ts and 93 pairs (Iand 93 pairs (Iii, D, Dii), is), is

4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.51

10

100

1000

2000IIIIVVVIVIIVIIIIX

Hyp

ocen

tral

Dis

tanc

e (k

m)

Predicted Magnitude (Msc)4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

Ms=-0.542+1.075(Msc)

Sur

face

-wav

e M

agni

tude

(Ms)

Predicted Magnitude (Msc)

±+++= ∑∑∑ 0.61P )(logR2.964j )(R0.000505j )(I0.549j3.336- M i1-

i1-

i1-

sc

j

i

j

i

j

i

Intensity AttenuationIntensity Attenuation

IntensityIntensity--Attenuation Model:Attenuation Model:I = B1 + B2(Ms) + B3(R) + B4logR + σP

The regression analysis for the whole data set, which consists oThe regression analysis for the whole data set, which consists of f 93 93 (I(Iii, D, Dii)) pairs corresponding to 25 events, gives the following mean pairs corresponding to 25 events, gives the following mean attenuation expression:attenuation expression:

R)0.0007483(-)

0 150 300 450 6004

6

8

10

12

Attenuation Law Isoseismal Values

Inte

nsity

Hypocentral Distance (km)

0 200 400 600 8002

4

6

8

10

12

M=7

M=8

M=6M=5

Alldata NE

Inte

nsity

Hypocentral Distance (km)

±+= 0.92P )3.966(logR- 0.0014(R) - )1.254(M6.702 I s

STRONG MOTION STRONG MOTION INSTRUMENTATIONINSTRUMENTATION

Why is Seismic Instrumentation Important ?Why is Seismic Instrumentation Important ?

It helps us to:It helps us to:�� Estimate the probable ground motion.Estimate the probable ground motion.

�� Locate earthquakes (Locate earthquakes (epicentreepicentre, magnitude, depth, magnitude, depth))

�� Tell how the structure behaves.Tell how the structure behaves.

�� Confirm how to strengthen the structure.Confirm how to strengthen the structure.

�� Improve our design procedures and codes leading Improve our design procedures and codes leading to to reduced costs but increased safetyreduced costs but increased safety for future for future structures.structures.

Jamuna Bridge Seismic Instrumentation ProjectJamuna Bridge Seismic Instrumentation Project

�� BUET is the Consultant BUET is the Consultant to JMBA, Ministry of to JMBA, Ministry of Communication, GOBCommunication, GOB

��Total Project Cost: Total Project Cost: TkTk 4 4 crorecrore

�� Instrumentation has Instrumentation has recently been installed recently been installed (May(May--July 2003)July 2003)

�� BUET will monitor and BUET will monitor and analyze seismic data for analyze seismic data for the next 5 yearsthe next 5 years

Existing Existing Seismic Seismic

Stations In and Stations In and ArroundArround

Bangladesh.Bangladesh.

86 88 90 92 9420

22

24

26

28

BAY OF BENGAL

BANGLADESH

BURMA

INDIA

INDIA

BHUTANNEPAL

ISC-1995 RRLJ-1998

LAT

ITU

DE

LONGITUDE

Seismic Stations Seismic Stations to be deployedto be deployed

BMDBMD

JMBAJMBADUDU--ColombiaColombia

Accelerometer Sensors on Bridge DeckAccelerometer Sensors on Bridge Deck

TriaxialAccelerometer

(Acceleration in 3 dirs.)

Uniaxial Accelerometer (Horizontal Transverse

Acceleration)

Seismic Data TransmissionSeismic Data TransmissionSpread Spectrum / GPSSpread Spectrum / GPS

Transmitting from the BridgeData Control Centre

Receiving East End, Bhuapur

Data Control CentreData Control Centre

Communication Box / Computer Continuous Data Streaming

• Continuous digital data is transmitted to the Data Acquisition Computer

• Events exceeding threshold acceleration will be recorded on the computer

Free Field Stations (JMBAFree Field Stations (JMBA--BUET Project)BUET Project)East Side: East Side: Bridge End, Mymensingh, Bridge End, Mymensingh, GazipurGazipur

West Side: West Side: Bridge End, Bridge End, BograBogra, , NatoreNatore

• Triaxial Accelerometer

• Internal Recorder(PCMCIA Card)

• Solar Panel Charging

Installation TeamInstallation Team

Strong Motion Strong Motion RecordingRecording

During June 16, 2004 During June 16, 2004 EarthquakeEarthquake

0 10 20 30 40-40

-20

0

20

40

West Free-field (16.06.04)

UD

Acc

eler

atio

n (c

m/s

2 )

Time (s)

0 10 20 30 40-40

-20

0

20

40EW

0 10 20 30 40-40

-20

0

20

40NS

0 10 20 30 40-20

-10

0

10

20

East Free-field (16.06.04)

UD

Acc

eler

atio

n (c

m/s

2 )

Time (s)

0 10 20 30 40-20

-10

0

10

20EW

0 10 20 30 40-20

-10

0

10

20NS

0 10 20 30 40-10

-5

0

5

10

Mymensingh Free-field (16.06.04)

UD

Acc

eler

atio

n (c

m/s

2 )

Time (s)

0 10 20 30 40-10

-5

0

5

10EW

0 10 20 30 40-10

-5

0

5

10NS

0 10 20 30 40-0.2

-0.1

0.0

0.1

0.2

mm

/s

Displacement

mm

Time (s)

0 10 20 30 40-10

-5

0

5

10Velocity

0 10 20 30 40-40

-20

0

20

40

cm/s

2 Acceleration

West Free-field (NS-component; 16.06.04)

-40 -30 -20 -10 0 10 20 30 40-40

-30

-20

-10

0

10

20

30

40

EW

(cm

/s2 )

NS (cm/s2)

0.1 1 10 201E-5

1E-4

1E-3

0.01

0.1

1

EQ: 16.06.04 EW NS UD

Fou

rier

Spe

ctru

m (

cm/s

)

Frequency (Hz)

0.1 1 10 200.1

1

10

20

Frequency (Hz)

Am

plitu

de R

atio

EQ 141003 191103 180304 030704

FF-WEST

COSMOSCOSMOS--WSSI WSSI Project Project

((60 SMA60 SMA--1 Type 1 Type

AccelerographsAccelerographs))

Equipment donated by Equipment donated by USGS in 2005USGS in 2005

MicrozonationMicrozonation Maps Maps based on SPTbased on SPT--N value and N value and

MicrotremorMicrotremor StudyStudy

COMBINED HAZARD INTENSITY MAP FOR DHAKA, BANGLADESH

Thank YouThank You

seismic zonation map of bangladesh. - indico...

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