geotechnical earthquake engineering · 2017. 8. 4. · 2.00 2.25 entire gujarat saurashtra mainland...

Geotechnical Earthquake

Engineering

by

Dr. Deepankar Choudhury Humboldt Fellow, JSPS Fellow, BOYSCAST Fellow

Professor

Department of Civil Engineering

IIT Bombay, Powai, Mumbai 400 076, India.

Email: [email protected]

URL: http://www.civil.iitb.ac.in/~dc/

Lecture – 30

IIT Bombay, DC 2

Module – 7

Seismic Hazard Analysis

IIT Bombay, DC 3

Example

Case Study

on Gujarat, India

Ref: Ph.D. Thesis of Jaykumar Shukla (2013),

IIT Bombay, Mumbai, India.

Seismic Zones of Gujarat, IS: 1893-Part I (2002)

Location of urban areas selected…

7/11/2013

Earthquake Moment Magnitude (Mw)

3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0

Log

N

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

Entire Gujarat

Saurashtra

Mainland Gujarat

Kachchh

Regional Seismicity parameters

7/11/2013

Gutenberg – Richter recurrence

relations are derived using Least

Square Fit method using prepared

earthquake catalogue for Mw ≥ 4.

Region Past seismicity

used (Year) a-value b-value G-R relation R2

Saurashtra 135 4.03 0.64 Log N=4.03 – 0.64 Mw 0.9783

Mainland 175 4.02 0.62 Log N=4.02 – 0.62 Mw 0.9370

Kachchh 189 3.41 0.41 Log N=3.41 – 0.41 Mw 0.9821

Gujarat 189 4.13 0.51 Log N=4.13 – 0.51 Mw 0.9899

Choudhury and Shukla (2011) in Disaster Advances, 4(2), 47-59.

Rastogi et al. (2013)

recommended b value

= 0.67 for Saurashtra

region.

b-value using ML method

• Another popular method for estimation of b-

value is by using Maximum Likelihood (ML)

method (Aki, 1965; Utsu, 1965)

7/11/2013

min

1

ln(10)( )b

u m

u is the sampling average of the magnitudes

Region b-value using ML estimate

Kachchh 0.526

Saurashtra 0.572

Mainland Gujarat 0.642

Various Probability Distributions No Year Month Date

Date

(Years)

Latitude

(0N)

Longitude

(0E) Mw

Recurrenc

e Time

(Years

Location

1 1819 6 16 1819.5 24 69 7.8 Kachchh

2 1845 4 19 1845.333 23.8 68.9 6.3 25.833 Lakhpat

3 1848 4 26 1848.333 24.4 72.7 6 3 Mount Abu

4 1856 12 25 1857 20 73 5.7 8.667 Surat

5 1864 4 29 1864.333 22.3 72.8 5.7 7.333 Ahmedabad

6 1871 1 31 1871.083 21.2 72.9 5 6.75 Surat

7 1872 4 14 1872.372 21.75 72.15 5 1.289 Bhavnagar

8 1882 6 10 1882.5 23.2 71.38 5 10.128 Bhachau

9 1903 1 14 1903.083 24 70 5.6 20.583 Kachchh

10 1919 4 21 1919.391 22 72 5.7 16.308 Bhavnagar

11 1921 10 26 1921.833 25 68 5.5 2.442 Kachchh

12 1935 7 20 1935.583 21 72.4 5.7 13.75 Surat

13 1938 3 14 1938.25 21.6 75 6 2.667 Satpura

14 1950 6 14 1950.5 24 71.2 5.3 12.25 Kachchh

15 1956 7 21 1956.583 23.3 70 6 6.083 Kachchh

16 1963 7 13 1963.583 24.9 70.3 5.3 7 Pakistan

17 1965 3 26 1965.25 24.4 70 5.1 1.667 Kachchh

18 1966 5 27 1966.417 24.46 68.69 5 1.167 Pakistan

19 1970 2 13 1970.167 24.6 68.61 5.2 3.75 Kachchh

20 1976 6 4 1976.5 24.51 68.45 5.1 6.333 Allah Band

21 1985 4 7 1985.333 24.36 69.74 5 8.833 Kachchh

22 1993 8 24 1993.732 20.6 71.4 5 8.399 Rajula

23 2001 1 26 2001.083 23.44 70.31 7.7 7.351 Kachchh

24 2006 3 7 2006.25 23.79 70.73 5.7 5.167 Gedi,

25 2007 11 6 2007.933 21.16 70.54 5 1.683 Junagadh

7/11/2013

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Cu

mu

lati

ve P

rob

ab

ilit

yEarthquake (M

w >= 5) in Gujarat region

Pareto Distribution

Rayleigh Distribution

Weibull Distribution

Exponential Distribution

Earthquakes


Recurrence Estimation

7/11/2013

Probability

Distribution

Model

Recurrence

interval

(years)

Predicted

Last Event

occurred on

Next

Earthquake

Expected on

Study Date

Considered

(Nov 10th

2009)

Year Left

from Present

Date

Next

earthquake

expected

before

Exponential 7.853 2007.933 2015.786 2009.85 5.936 Oct 2015*

Rayleigh 16.173 2007.933 2024.106 2009.85 14.256 Feb 2024

Pareto 3.135 2007.933 2011.068 2009.85 1.218 Jan 2011

Weibull 7.011 2007.933 2014.944 2009.85 5.094 Dec 2014*

*Note: This research output published in Journal Disaster Advances in Aug.

2011 was validated by actual occurrence of earthquake of September 2011.


b-value proposed & those by other researchers

Study

Number

Application area b- value Reference Periods for

study taken

1 Kachchh 0.417 Based on least square fit, Present Study (1820-2008)

2 Saurashtra 0.64 (1872-2008)

3 Mainland 0.62 (1872-2008)

4 Entire 0.51 (1820-2008)

5 Kachchh 0.526 Based on ML estimate, Present Study (1820-2009)

6 Saurashtra 0.572 (1872-2009)

7 Mainland 0.642 (1872-2009)

8 Saurashtra 0.67 Rastogi et al. (2013) (1970-2010)

9 Gujarat

0.87

( 0.06)

WCE NDMA (2010) (*1800-2009)

10 Gujarat 0.72 Tripathi et al., (2005) -

11 Kachchh 0.43 Ashara et al., (2006) -

12 Kachchh 0.71

0.03

Jaiswal (2006) (1842-2002)

13 Gujarat

0.7 to 0.9

0.07

Raghukanth (2010) (1250-2008)

14 Gujarat

0.4 to 0.6 Kolathayar et al. (2011)

for Clustered catalogue

(250 B.C. -2010)

15 Gujarat

0.4 to 0.8 Kolathayar et al. (2011)

for declustered catalogue

(250 B.C. -2010)

16 Peninsular 0.92 Jaiswal and Sinha (2007) (1842-2002)

17 Gujarat region 0.55 Bhatia et al. (1999) -

18 Gujarat 0.89 Thaker et al. (2012) 1818-2008

Shukla and Choudhury (2012) in NHESS, 12, 2019-2037.

• Entire Gujarat is divided into three regions

– Kachchh

– Saurashtra

– Mainland Gujarat

• Earthquake catalogue is divided as per these three regions

• Only fault sources are used as seismic sources

• Poisson distribution for earthquake occurrence

• All the faults are Normal faults, depth ranging 10 to 15km from

ground surface.

DSHA - Some starting points

1 • Describes the potential for dangerous, earthquake-related natural

phenomena i.e. Maximum Considered Earthquake (MCE)

2

• “The earthquake hazard for the site is a peak ground acceleration of 0.57g resulting from an earthquake of magnitude 5.7 on the Narmada Son Fault at a distance of 11.42 km from the site. ”

3 • Sometimes called Deterministic Scenario in Magnitude,

Distance pair i.e. (5.7, 11.42)

DSHA

67 68 69 70 71 72 73 74 75

67 68 69 70 71 72 73 74 75

19

20

21

22

23

24

25

26

19

20

21

22

23

24

25

26

F18

F17

F14 F15

F13

F12 F25A F5

F2

F1

F4

F3F6

F7

F8

F10

F9

F33

F35

F34

F37

F38 F42

F41

F43

F45 F46

F31

F32

F24

F49F23

F48

F27

F26

F21

F28

F29

F30

Legend :

n th Fault, Fn

Fault Map of study region

7/11/2013

• Total 40 major faults

are considered.

• Length derived from

referred literature and

maps.

• Maximum earthquake

magnitude calculated

from relationships

recommended by few

researchers

considering one third

length as rupture

surface.


GMPEs selected

7/11/2013

GMPE Applicability Remark

Abrahamson and

Silva (1997)

Worldwide shallow crustal

earthquake

Boore et al.

(1997)

Shallow crustal earthquake

of Western north America

(Rock site definition is in accordance

with NEHRP seismic code)

Campbell (1997) Worldwide shallow crustal

earthquake

(for Mw > 5 and sites with distance to

seismogenic rupture ≤ 60 km in active

tectonic region)

Sadig (1997) Shallow crustal earthquake

of California

(Moment magnitude Mw = 4 to 8 and

distance up to 100 km).

Toro et al. (1997) Crustal earthquake of

Intraplate region in Eastern

and Central North America

(For spectral period less than 0.2 sec,

values limited to 1.5 g and periods less

than 1 sec are limited to 3 g.)

Frankel et al.

(1996)

Intraplate region of Central

and Eastern North America

Raghukanth and

Iyengar (2007)

Peninsular India (For sites with shear wave velocity Vs

≥ 3.6 km/sec.)

Various GMPEs

7/11/2013

0 20 40 60 80 100 120 140 160 180 200

1E-3

0.01

0.1

Sp

ectr

al

accele

rati

on

s (g

)

Distance from Hypocenter (km)

Abra.-Silva (1997)

Boore-Joyner-Fumal (1997)

Campbell (1997)

Frankel (1996)

Sadigh (1997) Rock

Toro (1997)

Raghu Kanth & Iyengar (2007)

DSHA Results Name of

City/Urban Area

Location Deterministic Seismic Scenarios (Controlling Fault/Magnitude-Distance pairs)

Short Period (0.2 sec)

(two stored building)

Long Period (2 sec)

(highrise buidlings)

N0 E0 Fault Mw Distance (km) Fault Mw Distance (km)

Ahmedabad 23.030 72.580 F24 5.5 14.290 F17 7.0 171.240

Amreli 21.602 71.218 F6 5.5 15.500 F7 6.0 25.330

Anjar 23.112 70.023 F14 7.0 13.320 F14 7.0 13.320

Baroach 21.715 72.977 F33 5.5 7.190 F33 5.5 7.190

Bhavnagar 21.770 72.143 F30 5.5 8.000 F30 5.5 8.000

Bhuj 23.252 69.662 F14 7.0 14.500 F14 7.0 14.500

Dholavira 23.883 70.215 F17 7.0 5.000 F17 7.0 5.000

Dholera 22.248 72.195 F31 5.5 20.330 F28 6.0 33.030

Dwarka 22.241 68.966 F2 5.5 12.000 F13 7.0 89.240

Gandhidham 23.071 70.135 F14 7.0 15.960 F14 7.0 15.960

Gandhinagar 23.229 72.651 F26 5.5 31.570 F17 7.0 174.240

Jamnagar 22.466 70.066 F13 7.0 34.480 F13 7.0 34.480

Junagadh 21.515 70.456 F7 6.0 14.370 F7 6.0 14.370

Mandavi 22.833 69.346 F13 7.0 34.720 F13 7.0 34.720

Mehsana 23.598 72.380 F24 5.5 15.010 F17 7.0 143.610

Morvi 22.814 70.829 F14 7.0 59.090 F14 7.0 59.090

Palanpur 21.171 72.438 F24 5.5 10.250 F17 7.0 152.810

Patan 23.850 72.114 F49 5.5 15.600 F17 7.0 115.390

Porbundar 21.643 69.611 F2 5.5 11.640 F43 7.0 110.190

Rajkot 22.283 70.800 F13 7.0 83.280 F13 7.0 83.280

Surat 21.194 72.819 F34 5.5 17.760 F13 5.5 17.760

Surendranagar 22.718 71.637 F28 6.0 30.570 F17 7.0 105.020

Vadodara 22.306 73.187 F24 5.5 22.190 F24 5.5 22.190

Valsad 20.610 72.925 F37 5.5 19.000 F37 5.5 19.000

Veraval 20.912 70.353 F2 5.5 12.000 F2 5.5 12.000


Typical scenarios for Ahmedabad City

7/11/2013

0 1 2 3 4

0.01

0.1

F24 (Mw 5.5,14.29 km)

F17 (Mw 7, 171.24 km)

Sp

ectr

al A

ccel

erat

ion

s (g

)

Spectral Period (sec)

Ahmedabad city

Typical Deterministic Spectra Cities representing

Kachchh region has

very high ground

motions and

Mainland Gujarat

has lowest ground

motions. For

Saurashtra mixed

results are obtained.

Comparison of

present study with

IS: 1893 – Part I

(2002) spectra

7/11/2013

IS 1893 (2002)- Zone III

0.5 Fractile

0.84 Fractile

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Spe

ctra

l A

ccel

erat

ion

(g)

Spectral Period (s)

Deterministic Spectra Ahmedabad


Note: 0.5 Fractile = 50th percentile (representing

MCE) and 0.84 Fractile = 84th percentile

(representing SSE), with 5% damping

Deterministic scenarios

7/11/2013

Name of City/Urban

Area

PGA (g) IS: 1893 Part1 (2002) PGA in (g)

Median

(0.5

percentile)

Zone assigned PGA (MCE) PGA (DBE)

Ahmedabad 0.125 III 0.16 0.08

Amreli 0.116 III 0.16 0.08

Anjar 0.530 V 0.34 0.17

Baroach 0.220 III 0.16 0.08

Bhavnagar 0.230 III 0.16 0.08

Bhuj 0.620 V 0.34 0.17

Dholavira 0.670 V 0.34 0.17

Dholera 0.160 III 0.16 0.08

Dwarka 0.089 IV 0.24 0.12

Gandhidham 0.490 V 0.34 0.17

Gandhinagar 0.053 III 0.16 0.08

Jamnagar 0.200 IV 0.24 0.12

Junagadh 0.176 III 0.16 0.08

Mandavi 0.154 V 0.34 0.17

Mehsana 0.125 IV 0.24 0.12

Morvi 0.085 IV 0.24 0.12

Palanpur 0.160 IV 0.24 0.12

Patan 0.138 IV 0.24 0.12

Porbundar 0.160 III 0.16 0.08

Rajkot 0.060 III 0.16 0.08

Surat 0.094 III 0.16 0.08

Surendranagar 0.084 III 0.16 0.08

Vadodara 0.073 III 0.16 0.08

Valsad 0.091 III 0.16 0.08

Veraval 0.188 III 0.16 0.08


IIT Bombay, DC 19

Probabilistic Seismic

Hazard Analysis (PSHA)

for Gujarat, India

Four Seismicity models used

7/11/2013

1E-5

1E-4

1E-3

0.01

0.1

4 5 6 7 8

An

nu

al

Rate

of

Ev

en

ts >

Mw=

4

Earthquake Moment Magnitude (Mw)

F14 (Exponential, b-value LSF estimate) F14 (Exponential,b-value as per ML estimation)




F14 (Exponential, b-value=0.92, Jaiswal and Sinha (2007)) F14 (Characteristic Model)




Logic Tree simulations

7/11/2013

Logic Tree used in seismic hazard computations (Figures in the bracket show the weightage assigned in

seismic hazard computations) (Abbreviations: Raghu Kanth and Iyengar (2007) – RI07, Abrahamson and

Silva (1997)– AS97, Frankel (1996) – F96, Toro et al., (1997) – T97, Boore-Joyner and Fumel (1997) –

BJF97, Campbell (1997) – C97, Sadigh et al. (1997)- S97).

PSHA Calculation overview

7/11/2013

• Number of Faults = 40

• Number of Magnitude-Recurrence relations = 4

• Number of GMPEs used = 7

• For each city computations = 40 x 4 x 7 = 1120

• For PSHA map, 8430 grid points means = 8430 x 4 x 7 = 233520 computations carried out in present study….

• This can be handled using computer software like SEISRISK III , CRISIS 2007 , EZ-FRISK88 etc. and MS Excel.

Designation Chance of

Exceedance

Return

period

(Years)

Earthquake Designation

Level 1 50 % 72 Operational Basis

Earthquake (OBE)

Level 2 10 % 475 Contingency Level

Earthquake (CLE)

Level 3 2 % 2475 Max. Credible

Earthquake (MCE)

Which means each 1120/233520 computations are repeated for each

level of ground motion computations.

Performance Levels of Ground motions considered

7/11/2013

1E-4 1E-3 0.01 0.1 1

1E-11

1E-9

1E-7

1E-5

1E-3

0.1

2475 years return period


Ann

ual

freq

uenc

y of

exc

eede

nce

Peak ground acceleration, (g)

Ahmedabad


Typical Seismic Hazard Curve


7/11/2013

Comparison of Seismic Hazards

7/11/2013

1E-4 1E-3 0.01 0.1 1

1E-10

1E-9

1E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0.01

0.1

1



An

nu

al f

req

uen

cy o

f ex

ceed

ence

Peak ground acceleration, (g)

Ahmedabad

Amreli

Anjar

Dholavira

Dholera

Dwarka

Gandhinagar

Mandavi

Mehsana

Morvi

Palanpur

Patan

Porbundar

Surendranagar

Valsad

Veraval

Baroach

Bhuj

Gandhidham

Rajkot

Jamnagar

Junagadh

Bhavnagar

Vadodara

Surat


How to use these Hazard Curves…..

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

Retrun Period 2475 years



IS 1893 (2002)- Zone III

Spe

ctra

l Acc

eler

atio

n (g

)

Spectral Period (s)

Ahmedabad

Development of Uniform Hazard Spectra

7/11/2013

Deaggreagation analysis – Jamnagar city

7/11/2013

0.000

0.025

0.050

0.075

0.100

3 1 . 2 5

3 3 . 7 5

4 3 . 7 5

7 3 . 7 5

8 1 . 2 5

1 0 1 .2 5

1 0 8 .7 5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

Distance from site to source (km)

Pro

bab

ilit

y D

ensi

ty

Earthquake Moment M

agnitude (M w)

Sensitivity Analysis among Urban Cities

7/11/2013

Ahm

edab

ad

Am

reli

Anj

ar

Bar

oach

Bhu

j

Bha

vnag

ar

Dho

lavi

ra

Dho

lera

Dw

arka

Gan

dhid

ham

Gan

dhin

agar

Jam

naga

r

Juna

gadh

Man

davi

Meh

sana

Mor

vi

Pal

anpu

r

Pat

an

Por

bund

ar

Raj

kot

Sur

at

Sur

endr

anag

ar

Vad

odar

a

Val

sad

Ver

aval

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50


PG

A (

g)

Cities

Exponential model, b-value estimated using LSF method

Characterastic Earthquake Model

Exponential model, b=0.92, as per Jaiswal and Sinha (2007)

Exponential model, b-value estimated using ML method

Summary • The seismicity within the Gujarat is very complex and migrating in nature

and region wise not common. Seismic hazard assessment using single

seismicity parameter for entire Gujarat may not correctly represent to the

actual seismicity distribution.

• It is therefore important to carryout the seismic hazard analysis for

Gujarat region using regional seismicity parameters which are consistent

with present state of seismicity in the Gujarat.

• It is observed that in the prepared earthquake catalogue most of the events

are from historic records i.e before 1960 and seismicity rate was constant

up to 1962. After 1962, the seismicity rate within the Gujarat is observed

to be increased. However for larger earthquake magnitude threshold i.e.

Mw ≥ 4 catalogue can be considered to be complete for its use in seismic

hazard assessment.

7/11/2013

• The seismicity parameter (b-value) is calculated by two different

approaches namely Least Square Fit method and Maximum Likelihood

method. These parameters constitute the basic framework required for

seismic hazard assessment for Gujarat region.

• The b-values obtained using Least Square Fit are 0.41, 0.64 and 0.62 for

Kachchh, Saurashtra and Mainland Gujarat, respectively.

• The b-values estimated using the Maximum Likelihood estimations (Aki,

1965) are observed to be 0.53, 0.57 and 0.64 for Kachchh, Saurashtra and

Mainland Gujarat, respectively.

• For Kachchh region, the recurrence interval for the earthquake magnitude

Mw = 6 is less than the 25 years and Mw ≥ 7.5 it approaches 120 to 150

year. For both Mainland and Saurashtra region The recurrence interval

for earthquake magnitude Mw = 5 is greater than 25 years and for Mw = 6

it is more than 125.

Summary

• For earthquake magnitude Mw ≥5 in Gujarat region, it is observed that

Exponential Model and Weibull Model are appropriate probability

distributions for Gujarat region.

• Estimated seismic ground motions using Deterministic approach

advocates that across Gujarat region, the seismic activities thereby

seismic ground motions are dominated by the faults in the Kachchh

region.

• It is again interesting to note that two major faults in Kachchh region

namely F17 (Iceland Belt Fault) and F14 (Kachchh Mainland Fault) are

the major contributors to the seismicity in the entire Gujarat. It is also

notable that the present seismicity in Kachchh region is concentrated

near F14 (KMF) and the location of Bhuj earthquake of 2001 is also

close to this fault.

Summary

• Though the peak ground acceleration (PGA) values are not in close

agreement with those recommended by IS:1893 Part 1 (2002) for some

cities but overall seismic ground motion distribution across the Gujarat

region is more or less in agreement with regional distribution

recommended by IS: 1893 Part 1 (2002).

• It is observed that the seismic hazards for few cities are found to be

affected by near sources at lower spectral periods and by distant

sources at higher spectral periods. In presently study it is observed that

many cities of Gujarat like Ahmedabad, Gandhinagar etc. are

influenced by distance source seismicity at higher spectral periods.

• For all cities in the Mainland Gujarat, the present PSHA study results

in close agreement with the seismic ground motions recommended by

IS: 1893 Part 1 (2002).

Summary

IIT Bombay, DC 35

Some Earlier Seismic Hazard Analysis for

India: Case Studies

• Studies Carried out in India

– Jabalpur city

– Sikkim Himalaya

– Delhi

– Dehradun

– Guwahati

– Bangalore

– Kolkata

36

Jabalpur city

Final hazard map of Jabalpur (PCRSMJUA, 2005)

IIT Bombay, DC 37

Sikkim Himalaya

Nath, 2007

•Seismic Hazard analysis was

carried out deterministically by

considering the seismotectonic

parameters and presented

maximum credible earthquake

for Sikkim by Nath et al. (2006).

•Further developed new

attenuation relation for Sikkim

Himalaya, a finally he

developed seismic

microzonation map using

geographical information

system (GIS)

IIT Bombay, DC 38

Delhi • Site-specific Microzonation Study in Delhi Metropolitan City by

2-D Modelling of SH and P-SV Waves by Parvez et al. (2004),

Microzonation of earthquake hazard in Greater Delhi area by

Iyengar and Ghosh (2004), and Seismic Microzonation Studies

for Delhi Region by Rao and Neelima Satyam (2005) and First

Order Seismic Microzonation of Delhi, India Using Geographic

Information System (GIS) by Mohanty et al. (2006).

• Mohanty et al. (2006) prepared a first order seismic

microzonation map of Delhi using five thematic, layers viz., Peak

Ground Acceleration (PGA) contour, different soil types at 6 m

depth, geology, groundwater fluctuation and bedrock depth,

integrated on GIS platform.

IIT Bombay, DC 39

Delhi

Final hazard

map of Delhi

(Bansal and

Vandana,

2007)

40

Dehradun

Spectral acceleration map of Dehradun (Ranjan, 2005)

41

Guwahati

The total area has been grouped into five zones based on the hazard

index values, categorized as very high (>0.50) high (0.40-0.50)

moderate (0.30-0.40) low (0.20-30) and very low (< 0.20). Most of the

residential area falls in a moderate zone. (Nath, 2007)

IIT Bombay, DC 42

Bangalore

Peak ground

acceleration map

of Bangalore

using DSHA.

(Sitharam, 2008)

Based on 950 bore

hole data with SPT

and MASW at 56

locations

IIT Bombay, DC 43

Bangalore

PGA contour at

rock level with

10% probability of

exceedance in 50

years for

Bangalore city

(Sitharam, 2008)

IIT Bombay, DC 44

Kolkata

the major part of

Kolkata City can

experience PGA value

above 0.25g, which

suggests that Kolkata

is in seismic zone IV.

(Mohanty 2008)

In the seismic zonation

map, Kolkata lies on the

boundary of zone III and

IV (which suggest the

PGA value of 0.2 and

0.25g, respectively)

IIT Bombay, DC 45

End of

Module – 7

geotechnical earthquake engineering · 2017. 8. 4. · 2.00 2.25 entire gujarat saurashtra mainland...

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