title microtremormeasurement-based prediction of …...microtremormeasurement-based prediction of...

Title Microtremormeasurement-based prediction of ground shakingin Kathmandu Valley of Nepal

Author(s) Bhandary, Netra-Prakash

Citation

Matsue Conference Proceedings (The Tenth InternationalSymposium on Mitigation of Geo-disasters in Asia = 第10回地震・地盤災害軽減に関するアジア会議及び現地討論会)(2012): 50-52

Issue Date 2012-10-08

URL http://hdl.handle.net/2433/180417

Right

Type Presentation

Textversion publisher

Kyoto University

The Tenth International Symposium on Mitigation of Geo-disasters in Asia, MGDA, 2012.10.3-9, Japan

Microtremor measurement-based

prediction of ground shaking in

Kathmandu Valley of Nepal

Netra P. BhandaryGraduate School of Science and Engineering

Ehime University, JAPAN

1

Microtremormeasurement-based prediction of ground shaking in Kathmandu Valley of Nepal


Presentation Content

� Background information (Nepal and Kathmandu Valley)

� Microtremor Survey� Analysis and Results� Predominant period distribution map� Double predominant period� Concluding Remarks

2



Indian Plate

3



Kathmandu

Pokhara

MCT

MBTHFT

MCT: main central thrust

MBT: main boundary thrust

HFT: Himalayan frontal thrust

Active Thrust Faults

100km4



Nepal: Geology and Geomorphology

5



Earthquakes in Nepal and its Periphery DMG, Nepal, DASE France (1979-1999)

6

50

1



Major Earthquakes in Nepal Himalayan Region and

Zone of Seismic Gap (Avouac et al., 2001)

Zone of seismic gap

INDIA

TIBET

7


The Tenth International Symposium on Mitigation of Geo-disasters in Asia, MGDA, 2012.10.3-9, JapanWhen ??

Recorded Earthquake History of Nepal

8



Next Predicted Earthquake (within 10~20 years)

9



Talking of Extremity

� TransportationRoads, Bridges, AirportsUrban roads

� Glacier LakesMorain dam failure, debris flow, flooding

� Landslides� Communication� Hospitals� Schools� Government Buildings (Presidential Palace, Singh

Durbar, Ministry and Ministerial Department Buildings, etc.)

and so on

10



Damage in the 1934 Earthquake

Dharahara at present

Fall of Dharahara in 1934

earthquake

倒壊後

11



Ghantaghar and Kathmandu

Durbar Square

Collapse of Ghantaghar in 1934

earthquake

Destruction of Kathmadu

Durbar Square during 1934

earthquake

12

51

2



Bhaktapur Durbar Square （（1934 Earthquake1934 Earthquake））

Before the

earthquake

After the

earthquake

13



14

Damage distribution in 1934 Earthquake in Kathmandu Valley

Bhaktapur

Kathmandu

Lalitpur

Moderately damaged

area

Heavily damaged area

LegendDistrict

KathmanduBhaktapurLalitpur

Damage TypeHeavily DamagedModerately Damaged

Urban Area

(Rana, 1935)

� Southern and eastern

parts (Bhaktapur city area)

were damaged very

heavily than other areas of

the valley



Basic information (Kathmandu Valley)

• Three main cities: Kathmandu, Lalitpur, Bhaktapur

• Resident Population: About 5 million (estimated)

• Altitude: 1,300 (average）

• Estimated human death: 40,000 – 100,000

• Estimated Injury: 200,000

• Major Earthquake Recurrence Period: 80-100 years

• Minor Earthquake Recurrence Period: 10-20 years

• Less than 3 Richter Scale Earthquakes: Several times a year

15



Population growth in

Kathmandu Valley

(Source: Google Earth, www.google.com)

Kathmandu Valley

N

Population Growth

16



17

Rapid population increase

2001 Satellite image



Population: 1.1 million

(Population: 308,000)

(Population: 2.5 million)

AirportConfluence point

of Bagmati and Manohara rivers Koteshwor



Old buildings/houses

Slender buildings/houses

(Improper design??)

At Present

18

52

3



Vulnerable buildings with narrow

streets

19



Historical Monuments Historical Monuments (World Cultural (World Cultural Heritages)Heritages)

� Seven World Cultural Heritage Sites in Kathmandu Valley

� Together with the environmental degradation and scenic deterioration following the urbanization, the earthquake disaster risk has increased greatly

� Disaster risk: Earthquake and Landslides

20



Pashupatinath Temple

Changunarayan Temple21



Bouddhanath Stupa Swayambhunath Stupa22



Kathmandu

Lalitpur

Bhaktapur

Formation of Kathmandu Valley

23



Formation of Kathmandu Valley

24

52

4



Water Bowl Model

Shock Wave Transfer in Ground

Refraction

ReflectionIncident

wave

Soft strata

Hard strata

No refraction

Incident wave Complete

reflection

No reflection

Incident shock wave

Hard strata

Soft strata

No refraction

25



One cycle

Earthquake shock wave

Structural vibration

characteristics

Natural Time Period and Excitation

Time

Amplitude

26



Building Structures• Brick masonry……Recently: Cement mortar, Old

structures: Brick powder mortar, lime mortar, mud mortar

• Reinforced concrete……RCC framed structure, Concrete block or brick masonry walls

Major ProblemsMajor ProblemsMajor ProblemsMajor ProblemsMajor ProblemsMajor ProblemsMajor ProblemsMajor Problems

• Earthquake resistability of hospitals

• Secondary disaster (Fire, aftershocks, etc.)

• Evacuation space (not properly identified)

• Lifeline damage……water pipeline (very old), power line, liquefaction-induced road damage, etc.

27



Earthquake Disaster Risk in Kathmandu Valley and

Technical Studies

� UNDP Study (Year 1992)

� An Integrated Study of Earthquake Disaster Mitigation in Kathmandu Valley by JICA (Year 2001)

• Expected Earthquakes (Three cases)

• Liquefaction Analysis/Prediction

• Slope Failure Prediction

• Lifeline Damage Prediction (Power line, Water pipeline, Roads, Bridges, Telephone line, etc.)

• Building structural Damage Estimation

• Human Death Estimation

• Identification of Evacuation Path and Evacuation Space

28



Geotechnical Study Plan at Ehime University

• Geo-info Database Preparation and Application

• Microtremor Survey and Earthquake Motion Analysis/Simulation

• Installation of Earthquake Accelerometers, Data Acquisition

• Groundwater Flow Simulation

• Ground Subsidence Prediction, etc.

29



Status of Borehole Exploration in Kathmandu Valley (From 1980 to 2002)

30

52

5



Geo-info Database

Borehole Data：

Boreholes for various purposes

31



Geological Strata of Kathmandu Valley Ground (Sakai et al. 2001)

32



Microtremor Survey for Damage Prediction

Microtremor: vehicle movement, explosion, factory vibrations, etc.

Measurement

Data Analysis

Natural time period

Damage Prediction

Highly sensitive accelerometer

Fourier Analysis H/V Spectrum

H: Horizontal

V: Verticle

Natural time period estimation

33


The Tenth International Symposium on Mitigation of Geo-disasters in Asia, MGDA, 2012.10.3-9, Japan34

Microtremor sources

Tidal currents

Industrial

machines

Vehicles

Railway

Strong winds

Shock

waves

Measu-

rement

Points

Volcano

Kathmandu:

• Vehicle movement

• Winds

• Industrial machines

• etc.

(From Tokyo Soil Research)



Kathmandu

Lalitpur

Bhaktapur

0 2 4 6 81Km

MicrotremorSurvey Area

Urban Area

LegendKathmandu

Bhaktapur

Lalitpur

Microtremor Survey

35



MT Survey in Kathmandu Valley

36

52

6



Location for MT Survey in KV

LegendLegendLegendLegend

Grid_Points

Airport

Minor Road

Highway

Ü

0 1 2 3 40.5km

1 km

1 km

Kathmandu

Lalitpur

Bhaktapur

37



Velocity Sensor

Transducer

Computer for data recording

38

-0.004

-0.002

0

0.002

0.004

0.00 20.48 40.96 61.44 81.92 102.40 122.88 143.36 163.84 184.32 204.80 225.28 245.76 266.24 286.72 307.20

Time (T) Sec

Vel

. (cm

/s)

1111 6666 7777 8888 9999 10101010 11111111 12121212 13131313 14141414 151515152222 555544443333

Noise

-0.004

-0.002

0

0.002

0.004

0.00 20.48 40.96 61.44 81.92 102.40 122.88 143.36 163.84 184.32 204.80 225.28 245.76 266.24 286.72 307.20

Time (T) Sec

Vel

. (cm

/s)

1111 6666 7777 8888 9999 10101010 11111111 12121212 13131313 14141414 151515152222 555544443333

Noise

-0.004

-0.002

0

0.002

0.004

0.00 20.48 40.96 61.44 81.92 102.40 122.88 143.36 163.84 184.32 204.80 225.28 245.76 266.24 286.72 307.20

Time (T) Sec

Vel

. (cm

/s)

1111 6666 7777 8888 9999 10101010 11111111 12121212 13131313 14141414 151515152222 555544443333

Noise

-0.004

-0.002

0

0.002

0.004

0.00 20.48 40.96 61.44 81.92 102.40 122.88 143.36 163.84 184.32 204.80 225.28 245.76 266.24 286.72 307.20

Time (T) Sec

Vel

. (cm

/s)

1111 6666 7777 8888 9999 10101010 11111111 12121212 13131313 14141414 151515152222 555544443333

Noise

North- South (NS) component data

East- West (EW) component data

Vertical (UP) component data

Device and DataDevice and Data



Fourier

Analysis

Fourier Amplitude Versus Frequency (Frequency domain)

Frequency correspondences to maximum value of H/V ratio

gives the predominant frequency of the site

MT Instrument T

V

T

VThree velocity components

(EW, NS , and UP) are measured (Time domain)

H/V Spect. Ratio

MicrotremorMicrotremor data analysisdata analysis

39



40

P 163

0.1

1

10

100

0.1 1 10

P 8

0.1

1

10

0.1 1 10

P 133

0.1

1

10

100

0.1 1 10 100

P 100

0.1

1

10

0.1 1 10Frequency

H/V

spe

ctra

l rat

io

Frequency

H/V

spe

ctra

l rat

io

Frequency

H/V

spe

ctra

l rat

io

Frequency

H/V

spe

ctra

l rat

io

(F: Predominant frequency of the sites)

F = 3.0 HzF = 8.9 Hz

F = 0.73 HzF = 0.95 HzAnalysisAnalysis



North-South Profiles

Section South-NorthSection South-NorthSection South-NorthSection South-North

0

0.5

1

1.5

2

0 2 4 6 8 10 12

Distance from S-N (km)

Pre

dom

inan

t Tim

e P

eriod

S2-N2S3-N3S4-N4S5-N5S6-N6S7-N7S8-N8S9-N9S10-N10S12-N12S11-N11S13-N13S14-N14S15-N15S16-N16S17-N17S18-N18S1-N1S0-N0

BH1

BH2

BH3BH4

BH5


MT observat ion points

Road Networks

Ring Road

Airport±

0 1 2 3 40.5Km

1

6

5

4

3

2

9

8

7

11

00 3 4 5 6 7 8 9 10 112 12 13 14 15 16 17 181

10

Analysis ResultsAnalysis Results

41



Section West-EastSection West-EastSection West-EastSection West-East

0.0

0.5

1.0

1.5

2.0

2.5

0 2 4 6 8 10 12 14 16 18 20

Distance from W-E (km)

Pre

dom

inan

t Tim

e P

eriod

W0-E0

W1-E1

W2-E2

W3-E3

W4-E4

W5-E5

W6-E6

W7-E7

W8-E8

W9-E9

W10-E10

W11-E11

BH1

BH2

BH3BH4

BH5


MT observation points

Road Networks

Ring Road

Airport±

0 1 2 3 40.5Km

1

6

5

4

3

2

9

8

7

11

00 3 4 5 6 7 8 9 10 112 12 13 14 15 16 17 181

10

East-West Profiles

Analysis ResultsAnalysis Results

42

52

7



43

0.1

1

10

100

0.1 1 10

Period range D 1.01 s to 1.30 s

Period, s

H/V

spe

ctra

l ra

tio

0.1

1

10

100

0.1 1 10

Period range B 0.60 s to 0.80 s

Period, s

H/V

spe

ctra

l ra

tio

0.1

1

10

100

0.1 1 10

Period range C 0.80 s to 1.01 s

Period, sH

/V s

pect

ral r

atio

0.1

1

10

100

0.1 1 10

Period range E 1.30 s to 2.05 s

Period, s

H/V

spe

ctra

l ra

tio

H/V spectral ratio of 5 zonesH/V spectral ratio of 5 zones

Predominant period range

Description of zone

A 0.11 s to 0.60 s

B 0.60 s to 0.80 s

C 0.80 s to 1.01 s

D 1.01 s to 1.30 s

E 1.30 s to 2.05 s

0.1

1

10

100

0.1 1 10

Period range A 0.11 s to 0.60 s

Period, s

H/V

spe

ctra

l ra

tio

� The study area is divided

into five different range of

predominant periods

using natural break

technique, which regroups

similar values together

and represents the

distribution properly



44

Microtremor survey points

Major roads

Rivers

0.11-0.60 s

0.60-0.80 s

0.80-1.01 s

1.01-1.30 s

1.30-2.05 sDominant periods

Kathmandu

Lalitpur Bhaktapur

}Central Area

}Outer Area

Period range

EDCBA

Seismic microzonationmap of the study area

� Period in the study area varies from 0.1-2.05 s

� Period in central part varies from 1-2 s, which covers about 30% of the urban area of the valley



45

Predominant period contours for the Kathmandu Valley

� Higher period range in the eastern and western part of the valley is separated by the long low period line extended from north-west to south-east in the valley



46

Profiles based on the predominant period of ground

LegendMicrotremor survey pointsMajor roadsRivers

0.11-0.60 s

0.60-0.80 s0.80-1.01 s

1.01-1.30 s

1.30-2.05 sPredominant periods

(0, 0)



W10E10

S5

N5

BoreholeBorehole data and data and microtremormicrotremor analysis resultsanalysis results

47



W10E10

S5

N5

48

52

8



49

P 82

0.1

1

10

0.1 1 10

P 49

0.1

1

10

0.1 1 10Frequency

H/V

sp

ectr

al r

atio

Frequency

H/V

sp

ectr

al r

atio

f0

f1

f0f1

P 136

0.1

1

10

0.1 1 10Frequency

H/V

sp

ectr

al r

atio

f0

f1

P 152

0.1

1

10

0.1 1 10 100Frequency

H/V

sp

ectr

al r

atio

f0f1

f0 : first resonant frequency of the sites

f1 : second resonant frequency of the sites

Multiple

resonant

frequency



50

# Microtremor observation points

10111Major road

River and Water Bodies

Multiple amplified microtremorobservation points

About 35 (20%) measurement points exhibit double peaks and mostly in the central and northern part of the Valley

Location of double peak H/V spectral ratio



51

Kathmandu

Lalitpur

Bhaktapur

27 points in Kathmandu City

2 points in Lalitpur City

6 points in Bhaktapur City

Location of double peak H/V spectral ratio and frequency variation



52

0

2

4

6

8

5 18 29 43 50 53 62 79 82 85 92 93 94 95 96 98 99 114 115 116 125 127 128 131 136 137 142 143 149 150 152 153 159 160 170

First resonant frequency f0

Second resonant frequency f1

Am

pli

fie

d f

req

ue

nci

es

(Hz)

Microtremor observation points

Distribution of multiple resonant frequencies

� First resonant frequencies vary from 0.48 Hz to 1.52 Hz

� Second resonant frequencies vary from 3.1 Hz to 7.5 Hz, however mostly vary from 4 Hz to 6 Hz

� The ratio of second to first resonant frequency is found about 5



53

0

2

4

6

8

10

12

5 18 29 43 50 53 62 79 82 85 92 93 94 95 96 98 99 114 115 116 125 127 128 131 136 137 142 143 149 150 152 153 159 160 170

Amplitude of first resonant frequency A0

Amplitude of second resonant frequency A1

Am

pli

tud

e o

f H

/V c

urv

es

Microtremor observation points

Amplitude of multiple resonant frequencies

� Amplitude of the second resonant frequencies are found higher than the amplitude of the first resonant frequencies in some of the location



54

Legend

� Multiple amplified microtremorObservation points

# JICA PS logging point

Major roads

Study area

Rivers and water bodies

Airport

BH3

BH5BH4

BH2BH1

Location of double resonance area and JICA (2002) PS logging sites in

Kathmandu Valley

1

52

9



55

Bhaktapur Durbarsquare

(P50 and BH5)

Vsavg = 252.93 m/s (Shear wave velocity)

f1 = 5 Hz (2nd amplified frequency)

H1 = Vsavg/4f1

H1= 252.93/(4*5)

H1 = 12.64 m (Depth of the topsoil layer)

Estimation of top soil layer thickness

BH3BH5BH4

BH2BH1

LegendMultiple amplified Microtremor Observation pointsJICA PS logging pointMajor roadsStudy areaRivers and water bodiesAirport

JICA (2002)

Depth based on

microtremor observation



56

BH3BH5BH4

BH2BH1

LegendMultiple amplified Microtremor Observation pointsJICA PS logging pointMajor roadsStudy areaRivers and water bodiesAirport

Newroad

(P95 and BH1)

Vsavg = 188.86 m/s (Shear wave velocity)

f1 = 3.1 Hz (2nd amplified frequency)

H1 = Vsavg/4f1

H1 = 188.86/(4*3.1)

H1 = 15.23 m (Depth of the top soil layer)

Estimation of top soil layer thickness

JICA (2002)

Depth based on

microtremor observation



57

SN Borehole Location

Borehole ID

Average shear wave

velocity (m/sec)

Average shear wave

velocity upto30 m depth

for Kathmandu

Valley (m/sec)

246.87

1 New Road BH1 188.87

2 Singha Durbar

BH2 310.85

3 Jawolakhel BH3 247.33

4 Thimi BH4 234.40

5 Bhaktapur BH5 252.93

Legend

# JICA PS logging point

Major roads

Rivers and water bodiesAirport

BH1 BH2

BH3 BH4

BH5

� Average shear wave velocity based on JICA study for Kathmandu Valley (based on 5 PS

logging sites) = 246.87 m/sec (JICA, 2002)

� The second resonant frequency varies from 3.1 Hz to 7.5 Hz

� The depth of the top soil layer responsible for amplification of soil = 10 m -20 m

Estimation of top soil layer thickness in

the Kathmandu Valley



� Predominant period in the urban cores and peripheral settlements of the Kathmandu Valley varies from 0.1 s to 2.0 s, and that the period gradually decreases from a higher value in the central part of the valley to a low value in the outskirts.

� The trend of period variation is found to follow the distribution of sediment depth in the valley.

� In the central part, tall buildings and long-span bridges are susceptible to damage, while it is opposite in the outskirts.

� The investigation results show that two amplified frequencies appear at about 20% of the measurement sites, which are mainly distributed in the central and the northern part of the basin

� The first amplified frequencies vary from 0.5 Hz to 8.9 Hz, whereas the second amplified frequencies vary from 3.1 Hz to 7.5 Hz, in which most of them vary from 4 Hz to 6 Hz

� Depending on the area, especially in the central and northern part, the top 10-20 m of the sediment layer plays an important role in making the second resonant effect in the Kathmandu Basin

Concluding RemarksConcluding Remarks

Thank you58

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