Journal of Natural Disaster Science, Volume 33, Number 2, 2012, pp59-70

SEISMIC HAZARD ANALYSIS FOR INDONESIA
Rusnardi Rahmat PUTRA*,**
Junji KIYONO***
Yusuke ONO****
Hari Ram PARAJULI******PhD Student, Graduate School of Engineering, Dept. of Urban Management, Kyoto University, Japan**Lecturer, Civil Engineering Dept, Padang State University, Indonesia***Professor, Dept. of Urban Management, Kyoto University, Japan
Assistant
Professor, Department of Urban Management, Kyoto University, Japan*********Post Doctoral Fellow, RGIRO, Ritsumeikan University, Japan(Received January 6, 2011 Accepted January 10, 2012)
ABSTRACT
Based on compiled data during the period 1779-2010, 48,000 earthquake events
exceeding M4 had occurred in Indonesia. Since the earthquake data are available in various
magnitude scales, we converted all scales into moment magnitude. By using the catalogs
compiled, we constructed area earthquake source model and estimated the frequencymagnitude relationship. From recorded data by accelerometers installed at four stationsin Padang, we plotted observed data on the several existing attenuation equations andselected a suitable attenuation relationship for Indonesia. Peak ground acceleration on
10% probability of exceedance in 50 years for rock and soft soil condition were calculated.
We compared the expected acceleration with existing ones and discussed. Based on the
expected acceleration calculated, we proposed design spectra in several major cities inIndonesia.
Keyword: seismic hazard, earthquake, faults, source zone, areal model, design spectrum

1. INTRODUCTION

large number of earthquakes in the past. According
to catalogued events, the number of earthquakes thathave occurred in this region exceeds 48,000 with amagnitude greater than 4.0 from AD 1779 to 2010.
Most of the major historical earthquakes in Indonesia have caused significant damage to facilities (e.g.,
Utsu et al., 1992; Fauzi et al., 1999; EERI, 2010).
Many large earthquakes have occurred in the shallow
seas of the area that can produce massive tsunami likethe 2004 Banda Aceh event. This earthquake off thecoast of Sumatra resulted in hundreds of thousandsof deaths and a million people homeless (Ghobarah.

The Indonesian archipelago is located at theboundary of three major tectonic plates, the IndoAustralian, Pacific, and Eurasian plates, stretchingfrom Sumatra in the west to Papua in the east (Fig.1).
Indonesia is at the collision point of these three crustal plates. The high subduction-related seismicity inthis region means that tsunami and other earthquake
hazards are also high. Indonesia has approximately
17,504 islands, with a total land area of 1.92×106 km2
and a sea area of 3.26×106 km2. It has experienced a59

R. RAHMAT PUTRA, J. KIYONO, Y. ONO, H. RAM PARAJULI

A et al., 2006). The most recent one is the Mentawai
tsunami that occurred on October 25, 2010.
When Indonesian region clustered into two regions, the west cover Sumatera, Kalimantan and Java,on the other hand the east covers Bali, Flores, Timor,
Ambon, Sulawesi and Papua.
In western Indonesia (i,e. Java and Sumatra),Sumatra subduction zone is formed by the subductionof the Indian-Australian plate beneath the Eurasianplate at a rate of about 50 to 70 mm per year and thisis the main source of subduction-related seismicity (Prawirodirjo et al., 2000). Based on our catalog,
several giant earthquakes occurred in this region:
1779 (Mw8.4), 1833 (Mw9.2), 1861 (Mw8.3), 2004
(Mw9.2), 2007 (Mw7.9 and 8.4) and 2009 (Mw7.6).
Although the source of the 2009 Padang earthquake
on September 30 located in the ocean slab of the
Indian-Australian plate at (-0.81S, 99.65E) and its
depth of 80km. It produced a large shaking and severe
damage to houses and building in Padang and Padang
Pariaman, because its epicenter was about 60km offshore from Padang. As the Padang earthquake wasan intra-slab earthquake at intermediate depth withcomparable magnitude, the event did not generate
a tsunami of significance (EERI. 2010). Due to thisearthquake, about 1,117 people were killed, 1,214 severely injured, 1,688 slightly injured, and 3 missing.
Damage to houses is about 114,797 heavily, 67,198
moderate and 67,837 slightly. About 4,000 buildings
and 93 schools in Padang city were sustained damaged (Report, BNPB. 2009). This event occurred justa few minutes after office and school hour, but if it
struck earlier time, the higher number of causalities
would definitely occur resulted by buildings collapse.
The oblique convergence also results in lateraldisplacement along the Sumatera fault (Peterson etal., 2004). This fault also generates large destructive
earthquakes such as in 1892 (Mw7.1), 1943 (Mw7.6)
and 2007 (Mw6.4). These faults are capable of generating future strong ground motion that would affectto vulnerable structures. According to our catalogs,
the Sumatera fault produces a very high annual rateof earthquakes and many of the major earthquakes
occurred in shallow region under the Sumatra Island(Fig. 2).
In eastern Indonesia that covers Bali, Flores,
Timor, Ambon, Sulawesi and Papua, three major tectonic plates (Indian-Australian, Pacific, and Eurasianplates) interact each other. The Pacific plate subducts
beneath the Eurasian plate with a rate of about 100110mm per year at eastern Papua island (Hall et al.,2000). Subduction of Indian lithosphere beneath theBanda sea and the northern Australia plate boundary
is a complex- and active-deforming region which has
one of the fastest relative plate motions on the Earth(Hall et al., 2000). Based primarily on the tsunami records from 1608 to 2010 (Major et al. 2008), the eastern Indonesia experienced over 30 significant earthquake events such as 1938 (Mw8.5), 1976 (Mw7.1),
1992 (Mw7.8), 1996 (Mw8.1), 2006 (Mw7.1), 2008
(Mw7.5), 2009 (Mw7.6) and 35 tsunamis.
Probabilistic Seismic Hazard Analysis (PSHA)
aims to quantify the uncertainties and produces an explicit description of the distribution of future shaking
that may occur at a site (Baker, 2008). We consider
all possible earthquake events and estimate groundmotion along with their associated probabilities of occurrence in order to assess design ground motion forstructure. The annual probability of exceedance is determined for some level of earthquake shaking at site.
In this study,
We consider the earthquakes of which magnitudes are larger than 4.0 in moment magnitude scale,and adopt an areal model to determine source because
earthquake events may occur anywhere in the region(see Fig.2). For accelerometer records observed, we
compared several existing attenuation equations andselected a suitable one for Indonesia. In addition, we
calculated the seismic hazard for peak ground acceleration (PGA) with 10% probabilities of exceedancein 50 years and proposed design spectra at several
sites.
2. PROBABILISTIC SEISMIC HAZARD ANALYSIS
2.1 Earthquake catalog
Estimation of future seismicity is based on therate of past earthquake determined from earthquake
catalog. In this study, we compiled a new catalog of
instrumentally recorded by combining several sources
such as USGS catalog, ISC catalog (various bulletinof the International Seismological), Indonesian meteorology agency (BMG) and Tsunami catalog and zone
in Indonesia (Hamzah et al. 2000). The new catalog
is constructed by omitting overlap data of each source
catalog. Since the earthquake data have been reported
60

SEISMIC HAZARD ANALYSIS FOR INDONESIA

Malaysia
Singapore

Philippine Plate
Malaysia

Pacific plateIndo-Australian Plate

Fig. 1 Tectonic and plate boundaries, large arrows indicate the direction of plate motion

Legend:0 -100km
100-300km>300kmFig. 2 Seismicity map of Indonesia region, Mw>4. Data from USGS, ISC, Hamzah & Puspito, BMKG, the period 1779 - 2010
in different magnitude and intensity scale by thesource catalogs, all data converted to moment magnitude (Hank et al. 1979). Here we are interested in all
earthquake sources that have a potential to produce
damaging ground motions at the site. These sources
could be active faults and subductions, which are
typically planar surface indentified through various
means such as observation of past earthquake locationand geological evidence. If individual faults are not
identifiable then earthquake sources may be describedby an areal region in which earthquakes may occur
anywhere (Baker, 2008). In Indonesia, there are still

remains much uncertainty in active fault parameters,
therefore, we adopt an area source model that can be
determined only from historical earthquake data.
2.2 Source Zones and Recent Damage
In this study, we determine the earthquake
sources described by the areal region in which earthquake occurred within radius 75 km from a target
site. Main part of Indonesian island locates 95.0E to145.0E in longitude and -9.0S to 6.0N in latitude asshown in Fig.3. The area divided into 1,400 meshes
and frequency-magnitude relationship was calculated.
61

R. RAHMAT PUTRA, J. KIYONO, Y. ONO, H. RAM PARAJULI(Mw7.2) are included. The recent 2010 Mentawai
earthquake, that produced tsunami damage, caused
about 490 people dead and about 520 houses severely
damage (Padang City Government. 2010).
On the other hand, Banda Aceh city is the capitalof Aceh province. The population is approximately
260,000 as of 2006 and locates at (95.3E, 5.5N).
Same as Padang, Banda Aceh situates on the coast of
the Indian Ocean. According to historical earthquake
catalog, about 1,839 events occurred in this region
during the period from 1779 to 2010 (Fig. 5). Largeearthquakes occurred in 1936 (Mw7.1), 1967 (Mw6.1),
1983 (Mw6.6), 1990 (Mw6.8) and December 26, 2004
(Mw9.3). When the 2004 Indian Ocean earthquake
struck off the western coast of Sumatra, Aceh province
including the cities of Banda Aceh, Calang and Maulaboh, were among hardest-hit areas by the tsunami.
Banda Aceh city was the major closest city to theearthquake epicenter, and suffered destructive damage when the tsunami struck shortly afterwards. About
167,000 people died and more were injured. Tsunami
resulted from an earthquake with moment magnitude
9.3 and struck at about 6:58 am. The epicenter was
about 155 mile off the coast of Banda Aceh. Massive
tsunami wave wiped out entire coastal areas acrosssoutheastern Asia, Sri Lanka, India, Thailand, Myanmar, island in the Andaman Sea and the Maldives in
the Indian Ocean. The death toll thus has been reported
as 260,000 and more than 1.5 million people became
homeless around this region (Ghobarah et al. 2006).

Probabilistic seismic hazard analysis carried out to estimate seismicity at the site. Firstly, hazard curves for
Padang city and Banda Aceh city were calculated andcompared because these cities have many experiencesof giant earthquakes that produced high number of
causalities and destroyed many infrastructures in theprevious years.
The city of Padang, located on the west coast of
Sumatra in western Indonesia, lies close to the Sumatran subduction zone that is formed by the subductionof the Indo-Australian Plate beneath the Eurasian
Plate. Relative motion of the plates occurs at a rate ofabout 50 to 70 mm/year and this is the main source of
subduction-related seismicity in the area (Prawirodirjo
et al., 2000), and the Sunda trench fault. Each fault
is still active until now with the slip rate ranges from10 to 27 mm/year (Natawidjaja et al., 2007). The cityof Padang , with a population of 856,814 people asof 2008, is the capital of West Sumatra province. The
location of the city center is at 100.38°E, 0.95°S. The
population density is very high, about 8500 people/
km2. About 80% of population lives in seaside (Padangcity government, 2009).
According to our catalog, about 2,995 eventsoccurred in this region during the period from 1779
to 2010 (Fig. 4). Many giant earthquakes such as in1779 (Mw8.4), 1833 (Mw9.2), 1861 (Mw 8.3), twotimes in 2007 (Mw7.9 and 8.4), the recent Padang
earthquake on September 30, 2009 (Mw7.6) and thelatest Mentawai earthquake on October 25, 2010

6°

95°

145°
6°

-10°

-10°

95°

Fig 3 Indonesia area analyzed and two red circles are two samples of source zone with

145°

Fig. 3 Indonesia area analyzed and two red circles are two samples of source zone with 75 km radius for Padangcity and Band Aceh
62

SEISMIC HAZARD ANALYSIS FOR INDONESIA

much longer time frame, such as about 100 years. It isessential to identify the interval of complete recordingfor different magnitude ranges. To minimize the effects of incompleteness, an empirical and statisticallysimple method by Stepp (1972) was adopted.
The compute a cumulative distribution function(CDF) for the magnitudes of earthquake that larger
than some minimum magnitude mmin, Eq. (1) can bealso utilized. There generally is a limit on the upperbound of earthquake magnitude in a region, due tothe finite size of the source faults (Baker. 2008). If amaximum magnitude can be determined as

Legend:0 -100km
100-300km>300kmFig. 4 Seismicity map of Padang city, Mw>4, theperiod from 1779 to 2010‫ܨ‬ெ ሺ݉ሻ ൌ
Legend:0 -100km
100-300km>300kmଵିሺଵ଴ሻష್൫೘ష೘೘೔೙ ൯ଵିଵ଴ష್൫೘೘ೌೣష೘೘೔೙ ൯(2)( ݉௠௜௡ ൏ ݉ ൏ ݉௠௔௫ )where FM (m) is the cumulative distribution function
for M. The probability density function (PDF) for M
can be computed by taking the derivative of the CDF.

݂ெ ሺ݉ሻ ൌ௕௟௡ሺଵ଴ሻష್൫೘ష೘೘೔೙ ൯ଵିଵ଴ష್൫೘೘ೌೣ ష೘೘೔೙ ൯(3)( ݉௠௜௡ ൏ ݉ ൏ ݉௠௔௫ )Fig. 5 Seismicity map of Banda Aceh, Mw>4, theperiod from 1779 to 2010

where fM (m) is the probability density function for
M, mmax is a maximum magnitude earthquake fromsource. From the continuous distribution of magnitude, it will be converted into a discrete set of magnitude as follows.

2.3 Identify Earthquake Magnitudes
Subduction and faults are capable of producing
earthquakes with various sizes of magnitudes. The
distribution of these earthquake sizes in region generally follows a particular distribution (Gutenberg et al.
1944) given as݈‫ߛ݃݋‬௠ ൌ ܽ െ ܾ݉ܲ൫‫ ܯ‬ൌ ݉௝ ൯ ൌ ݂௠ ൫݉௝ାଵ ൯ െ ݂௠ ሺ݉௝ ሻ(4)

where mj < mj + 1, and mj are the discrete set of magnitude. Here we calculated the probability associatedwith all magnitude between mj and mj + 1, mj started
from magnitude 4 to maximum magnitude in our historical data and mj + 1 is at interval of 0.25.

(1)where γm is the mean annual rate of exceeding of magnitude m, a and b parameter are generally obtained byregression on database of seismicity from the sourcezone of interest. The a value indicates the overall rateof earthquake in a region, and the b value describe therelative likelihood of large and small earthquake. It
is obvious that smaller earthquake events occur more
frequently than the larger ones, and hence the recurrence rates of smaller earthquake can be evaluatedeven from the most recent data of the last 15-20 years.
On the other hand, for larger events have to consider a

3. GROUND MOTION INTENSITY
Ground intensities are referred to attenuation
equation or ground motion prediction. The groundmotion prediction models are obtained by developing
statistical regression on observation data from large
libraries of observed ground motion intensities (Baker.
2008).
In Padang, there are four accelerometers, three63

R. RAHMAT PUTRA, J. KIYONO, Y. ONO, H. RAM PARAJULI

of 10-300km, the soil condition are rock and soil site,2) The earthquake sources is subduction interface,Mw>5.0 with a hypocenter distance of 10-500km, thesoil conditions are rock and soil site. 3) The earthquake sources is subduction interface, all sources data
is from Sumatran earthquakes, Indonesia, Mw>5.0
with an epicentral of 150-1500 km, the soil condition
is rock site.
They are compared with peak ground acceleration observed at 2 stations in Padang (Figs. 7 and 8).
As no attenuation equation is currently exist in Indonesia, a suitable attenuation equation for Indonesia isdetermined.
Peak ground accelerations plotted are the data forearthquakes occurred in 2009 (Mw4.3 and Mw6.1).

accelerometers were donated by the Engineer without
Border, Japan (EWBJ) and the other was installed byIndonesian Government (Fig. 6).

Fig. 6 Accelerometer in Padang city
observed data

We also carried out microtremor array investigation at each station PDG001, PDG002 and PDG003 todetermine the soil condition of subsurface structures(Ono et al. 2010). From the dispersion curve of arrayobservation, we obtained the following results of Vs30
(average shear wave velocity of upper 30m soil profile): The value at PDG001 is 1323m/sec (1st layer of
3m thickness is 163m/sec, 2nd layer of 8m thickness
is 409m/sec and 3rd layer of 19m thickness is 1891m/
sec) and at PDG002 is 470m/sec (1 st layer of 2m
thickness is 135m/sec, 2nd layer of 10m thickness is
468m/sec and 3rd layer of 18m thickness is 508m/sec).
By considering the these results, the soil condition at
PD001 and PDG002 are corresponding to the hardsoil of which 30m-averaged shear velocity (Vs30) are
greater than 400m/s (Tselentis et al. 2008). Therefore,
we assume that the soil type at stations of PDG001
and PDG002 is engineering bedrock with the shear
wave velocity of 400<V s30<700m/s. We surveyedseveral attenuation relationships based on physicalcharacteristics such as an earthquake source, seismotectonic environment and the saturation of acceleration amplitude in a near-source region of which extent
depends on the size of the earthquake.
Taking into account above characteristic, threeattenuation equations by Fukushima et al. (1999),
Young et al. (1997) and Megawati et al. (2005) wereselected. The conditions of data used for attenuation
equations for 1) Fukushima et al., 2) Young et al., and
3) Megawati et al., are: 1) The earthquake sources issubduction interface, Mw>5.0 with a shortest distanceAcceleration (gal)

1000
Fukishima&Tanaka

100
10

Megawati

1

Young

0.1
0.01
0.001
1

10

100

1000

Distance (km)Acceleration (gal)Fig. 7 Comparison of attenuation relation for subduction zone and rock condition, Mw=4.3

1000

observed data

100

Fukushima&Tanaka

10

Megawati
Young

1
0.1
0.01
0.001
1

10

100

1000

Distance (km)Fig. 8 Comparison of attenuation relation for subduction zone and rock condition, Mw=6.1
From the comparison, we adopted Fukushima’s
attenuation as an appropriate equation and applied toseismic hazard analysis.

64

SEISMIC HAZARD ANALYSIS FOR INDONESIA

where λ (IM > x) is the annual earthquake occurrence
rate of which peak value exceeds a given level, x;λ (Mi > mmin) is the rate of earthquake with magnitude
greater than m, P (IM > x|mj, rk) is the probability ofoccurrence of the associated magnitude and distance;
P (Mi = mj) is the probability associated with all magnitude between mj and mj + 1 to the discrete value mj;
P (Rj = rk) is the probability of occurrence of the associated distance. Following above procedures, theseismic hazards for Padang city and Banda Aceh city
are estimated (Fig. 9). The tendency of the curve isalmost same because both cities locate under the sameenvironment of seismic activities along the Sumatra
subduction zone and the Sumatra fault (zone 7). The
expected acceleration for annual rates of exceedance,
0.002 (475 years) is 0.73g and 0.70g, respectively.

݈‫ ܣ݃݋‬ൌ ͲǤͶͳ ‫ܯ  כ‬௪െ ሺܴ ൅ ͲǤͲ͵ʹ ‫Ͳͳ כ‬଴Ǥସଵ‫כ‬ெೢ ሻ (5)െ ͲǤͲͲ͵Ͷܴ ൅ ͳǤ͵in which A is peak ground acceleration; Mw is moment magnitude; R is close distance to epicenter; andσ is standard deviation and its value is 0.21. According to Fukushima’s formulation, when the peak horizontal accelerations at the site for rock and soft soil
condition are estimated, the value derived from Eq. (5)have to be multiplied by 0.60 and 1.4, respectively.
The logarithm of PGA assumed to obey normally
distributed to compute the probability of exceeding any
PGA level by using the mean and standard deviation.
തതതതതതതതതതത
௟௢௚௫ି௟௢௚௉ீ஺
ఙ೗೚೒ುಸಲ

ሻ (6)mean annual rate of exceedance per
yearܲሺܲ‫ ܣܩ‬൐ ‫ݔ‬ȁ݉ǡ ‫ݎ‬ሻ ൌ ͳ െ Ȱሺin which Φ(*) is the cumulative distribution function.
Eq. (6) is used to compute the cumulative distributionfunction P(PGA>x|m,r,), m, r, and x are magnitude,
distance and acceleration respectively.
Eq. (6) can be also expressed by using the probability density function as follows‫ן‬ሺܲ‫ ܣܩ‬൐ ‫ݔ‬ȁሺ݉ǡ ‫ݎ‬ሻሻ ൌ ‫׬‬௫ ݂௉ீ஺ ሺ‫ݑ‬ሻ݀‫ݑ‬

(7)

i=1

Banda Aceh city
0.1

0.01

0.002

0.001
Acceleration (g)1

One of the advantages of probabilistic seismic
hazard analysis is that we can account for all possible
earthquake source in area. A disadvantage of PSHA
is that concept of design earthquake is lost. Whichearthquake scenario is most likely to cause PGA>x?.
Various researchers (Mcguire 1995, Chapman 1995,
Harmsen et al., 1999 and Harmsen et al., 2001) havedeveloped a model for deaggregation of hazard, calculated means and modal magnitude and distance.
The mean rate of exceedence is corresponding toparticular value of response acceleration at specified
probability of exceedences specified period at year
(e.g. 10% in 50 years) is a sum of all contribution ofmean rate of exceedences from various magnitudes
and distances.
In Figs.10 and 11 shown the deaggregation results of peak ground accelerations for PGA >0.2g with

nM nR

j=1 k=1

1

Fig. 9 Comparison of total hazard for Padang city
and Banda Aceh city at 10% probability ofexceedance in 50 years

Seismic hazard curve describes the aggregate
hazard at a particular site. The seismic hazard H (A)is defined as the annual occurrence rate of earthquakethat produce a ground motion exceeding a given levelat a specific site, base on Cornel et al. (1968) and McGuire et al. (1976). The overall hazard is composedof the respective contribution Hi (A) from each sourcezones, i, out of the set of zone I as shown in Eq. (8).
The range of possible Mi and Ri have been discretized
into nM and nR interval, respectively, by using the discretization technique.

Ȝ(IM>x)= Ȝm(Mi>mmin)  P (IM>x|mj,rk)

Padang city

0.1

where fPGA (u) is the probability density function of
PGA, given m and r.
.
4. SEISMIC HAZARD CURVE

sources10(8)*P(Mi=mj)P(Rj=rk)

65

R. RAHMAT PUTRA, J. KIYONO, Y. ONO, H. RAM PARAJULI

10% probability of exceedance in 50 years for Padangcity and Banda Aceh. Seismic hazard at Padang city
(Fig.10) has the most marked magnitudes Mw5.0 with
0-45km distance, and larger magnitude (Mw7.25-8.0)
are relatively higher contribution compared with seismic hazard for Banda Aceh (Fig.11). Seismic hazard
at Banda Aceh (Fig.11), the most frequent magnitudes
are Mw.5.0-5.25 with 0-45km distance, and larger
magnitudes (Mw7.25-8.0) are relatively lower contribution compare with seismic hazard for Padang city.
By doing the same procedure for seismic hazard

analysis as mentioned at above, we determined seismic hazard map for all Indonesian regions, which thepeak ground accelerations at 10% probability of exceedance in 50 years shown in Fig. 12 and the rangesof acceleration in the legend are the same as those in
Fig.13, that shows hazard map of Indonesia.
We compared our result with existing hazard
map of Indonesia in 2002 (Fig. 13) for bedrock condition. In Fig.13, the area is classified into zones forhazard, each zone determined from ground peak acceleration.

0.4

0.3

Contribution (%)

Contribution (% )

0.4

0.2
0.1
0
0

15

30

Distance (km)

45

60

75
5.0

5.5
5.25

6.0
5.75

7.0
6.75
6.50
6.25

8.0
7.75
7.50
7.25

0.3
0.2
0.1
0
0

15

Distance (km)Magnitude (mw)

30

45

60

75
5.0

Fig. 10 Deaggregation of peak ground acceleration
for PGA >0.2g, 10% probability of exceedance in 50 years for Padang city.

5.5
5.25

6.0
5.75

7.0
6.75
6.50
6.25

8.0
7.75
7.50
7.25

Magnitude (mw)

Fig. 11 Deaggregation of peak ground acceleration
for PGA >0.2g, 10% probability of exceedance in 50 years for Banda Aceh city.

Legend :
Zone
1

0.05g

2

0.15g

3

0.2g

4

0.25g

5

0.3g

6

0.4g

7

0.6g

Fig. 12 Result, the seismic hazard map of Indonesia for return period 475 years, for engineering bedrock condition.
66

SEISMIC HAZARD ANALYSIS FOR INDONESIA

Legend :Zone
1
0.03g 42
0.10g 53
0.15g 6

0.20g
0.25g
0.30g

Fig. 13 Copy of the seismic hazard map of Indonesia for return period 475 years, for bedrock condition

From the comparison of existing hazard map andproposed one, we obtained the value of acceleration
at 10% in 50 years for propose one is increase 25%
through 100% at every site. The differences of thevalues might be mainly caused by the number of datacollected, in which many earthquakes with magnitude
greater than 6 occurred after 2002 are included. The
other reasons come from the difference of attenuation
equation (Chapter 3) and the difference of definition
for bedrock. In Indonesia code, it is defined as thelayer of Vs>750m/sec, however, this paper defined it
as average shear wave velocity of upper 30m soil profile Vs>400m/sec.

ability of exceedance in 50 years.
According to SNI in chapter 4.7.6, the maximum acceleration response is calculated as follows;‫ܣ‬௠ ൌ ʹǤͷ‫ܣ‬଴ (9)in which A0 is the maximum earthquake ground motion considered, which is defined with uniform likelihood of exceedance of 10% in 50 years (approximate
return period of 475 years). The schematic diagram isshown in Fig. 14. The value, 2.5 is amplification factors for 5% damping (Newmark et al. 1978). Periodrelated parameters, T0 and Tc , are determined as follows; T0 = 0.2 sec and Tc = 0.5, 0.6, 1.0 sec for rock,medium (stiff soil) and soft soil (SNI. 2002), respectively. Earthquake response factor, (C ) is calculated
as follows

5. DESIGN RESPONSE SPECTRUM
From probabilistic seismic analysis, we apply theobtained results to propose design response spectra. It
becomes a useful tool for earthquake-resistant design
and geotechnical response analysis. The response
spectrum can also be used to represent seismic loading for the static and dynamic analysis of structure.
In this study, we adopt Indonesian code (SNI2002) to determine the design response spectrum. The
conditions of data used for Standar Nasional Indonesi(SNI2002) are Mw>5.0 with a shortest distance of
0-300km, the soil condition are rock and 10% prob-‫ ܥ‬ൌ ‫ܣ‬௠஺‫ ܥ‬ൌ ೝ்‫ܣ‬௥ ൌ ‫ܣ‬௠ ‫ܶ  כ‬௖

67for ܶ ൑ ܶ௖(10)for ܶ ൐ ܶ଴

(11)
(12)

R. RAHMAT PUTRA, J. KIYONO, Y. ONO, H. RAM PARAJULI

Because Banda Aceh city and Padang city locate
at the same zone 7, in other to, the purpose of design
response spectrum showed in the same figure (Fig.
16).
The proposed response spectrums show that thevalue of acceleration at each soil type for zone 6 and7 increased about 50% through 121% by comparing
with existing response spectrum in 2002. The differences of the values mainly caused by the difference
value of peak ground accelerations at 10% probabilityof exceedance in 50 years from each hazard map.

‫ܣ‬௠
‫ܣ‬௥
ܶ௖

ܿൌ
‫ܣ‬଴

T0

Tc

Period (s)Fig. 14 Design acceleration response spectrum

6. CONCLUSIONS
From the comparison of existing hazard map
and proposed one, the result of this study shows thatthe ground peak acceleration of 475 years at everysite is higher about 30% through 90% compared withexisting seismic hazard of Indonesia. The differencesof the values might be mainly caused by the numberof data collected, in which many earthquakes withmagnitude greater than 6 occurred after 2002 areincluded. The other reasons are difference on attenuation equation and the definition for bedrock. The definition of engineering bedrock in our study is average
shear wave velocity of upper 30m soil profile (Vs30) >400m/sec and Vs > 750m/sec for existing hazard map(SNI. 2002).
From the comparison of total hazard curve forBanda Aceh city and Padang city, Banda Aceh has
higher value of the peak ground acceleration at 10%
probability of exceedance in 50 years is 0.73g and
0.7g for Padang city. The proposed response spectra
is larger than existing response spectra about 50%
through 121%, it is due to deference of attenuation
equation and bedrock level.
The next prospective is to estimate the effective
peak velocity in Indonesia region for determining theexactly value of To and Tc. Because based on Indonesian code (chapter 4.7.6), it does not take into accountthe peak velocity for determining the value of To andTc.

Acceleration (g)Based on our analysis, we propose new response
spectra for Jakarta (the capital of Indonesia), Banda
Aceh city and Padang city. The results shown in Figs.
15 and 16.

Softmedium
rock

2.2
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
0

0.5

1

1.5

2

2.5

3

3.5

Period (sec)

Acceleration (g)Fig. 15 Design Response spectrum 5% damping
for Jakarta (zone 6)

2.2
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0

rock
soft
medium

0

0.5

1

1.5

2

2.5

3

ACKNOWLEDGMENTS

3.5

Period (sec)

We would like to express our sincere gratitude to
the Director General of Higher Education for the Indonesian Government (DIKTI) for financial support.

Fig. 16 Design response spectrum 5% damping for
Banda Aceh city and Padang city (zone 7)

68

SEISMIC HAZARD ANALYSIS FOR INDONESIA

Special thanks are provided to the Engineer Without
Border, Japan (EWBJ) who installed three accelerometers in Padang, and we used the data in our study. We
gratefully acknowledge Dr. Abdul Hakam, School of
Civil Engineering, Andalas University. Finally, a special thanks to Suhardjono M.eng, Director of BMKG,
who provided time history data for the 2009 Padang
earthquake and observation data by accelerometers
around Indonesia region.

eastern United States, Bull. Seismol. Soc. Am., 89(1),1-13.
Harmsen,S., Perkins, D. and Frankel, A, 2001. Mean andmodal ε in the deaggregation of probabilistic groundmotion, Bull. Seismol. Soc. Am.,91(6),1537-1552.
Kramer, S. L, 1996. Geotechnical earthquake engineering,106-138, Prentice-Hall International Series in Civil
Engineering and Engineering Mechanic.
Major, J.R, Robinson, J.S and Harrris, R.A, 2008. Earthquake and tsunami history and hazards of eastern In-

REFERENCES

donesia, American Geophysical Union, Fall Meeting
2008.
McGuire, R.K, 1976. Seismic hazard and risk analysis,

Baker, Jack W, 2008. Introduction probabilistic hazard
analysis, Handbook, Version 1.3 Oct 1st 2008.

Earthquake Engineering
Institute, MNO-10.

BNPB, 2009. Total damage report and verification for West

Megawati, K., Pan, T.-C. and Koketsu, K, 2005. Response

Sumatra due to Padang earthquake, available at http://

spectral attenuation relationships for Singapore andwww.bnpb.go.id.
Chapman, M.C, 1995. A probabilistic approach for groundthe Malay Peninsula due to distant Sumatran-fault

motion selection for engineering design, Bull. Seimol.

earthquake, Earthquake Engineering and Structural

Soc. Am. 85, 937-942.

Dynamics, Vol. 32, No. 14, pp 2241-2265.

Cornell, C.A. and Winterstein, S.R, 1968. Temporal andNatawidjaja and Wahyu Triyoso, 2007. The Sumatran fault

magnitude dependence in earthquake recurrence mode,zone-from source to hazard, J. of Earthquake and Tsunami Vol.1 No.1 (2007) 21-47.

Bull of the Seismological Society of America, 78(4),Newmark, N. M. and Hall, W.J, 1978. Development of cri-1522-1537.

teria for earthquake resistant design, Report NUREG/

EERI, 2010. The M<S>w</S> 7.6 Western Sumatra earth-CR-0098, Nuclear Regulatory Commission, Washing-quake of September 30, 2009, Special Report.

ton D.C., 49pp.

Fauzi, 1999. Private home page, Available at http://www.

Ono, Y., Kiyono, J., Rusnardi, P. R. and Noguchi, T, 2010.

gretchen.geo.rpi.edu /fauzi/xt.
Fukushima, Y. and Tanaka, T, 1999. A new attenuation rela-

Microtremor observation in Padang city, Indonesia totion for peak horizontal acceleration of strong earth-estimate site amplification of seismic ground motion,quake ground motion in Japan, Bull of the Seismologi-

Proc. of International Symposium on a Robust andcal Society of America. Soc. Am. 80, 757-783.

Resilient Society against Natural Hazards and Envi-

Ghobarah, A. and Danciu, L, 2006. The impact of the 26

ronmental Disasters and the third AUN/SEED-Net Re-

December 2004 earthquake and tsunami on structures

gional Conference on Geodisaster Mitigation, pp.386391.

and infrastructure, J. Engineering Structure 28, 312-

Padang City Government, available at http://www.Padang.

326.

go.id

Gutenberg, B. and Ricther, C.F, 1944. Frequency of earth-Peterson Mark D., James Dewey., Stephan Hartzell.,quake in California, Bull of Seismological Society ofCharles Mueller., Stephan Harmsen., ArthurD. Frankel

America, 34(4), 185-188.
Hall, R. and Wilson, M.E.J, 2000. Neogene suture in easternand Ken Rukstales, 2004. Probabilistic seismic hazard

Indonesia, J. of Asian Earth Science, 34:185-188.

analysis for Sumatera, Indonesia and across the South-

Hamzah and Puspito, 2000. Tsunami catalog and zones in

ern Malaysian Peninsula, Tectonophsysics 390 (2004)
141-158.

indonesia, J. of Natural Disaster Science, Volume 22,

Prawirodirjo, L. and Y. Bock, J.F, 2000, One century of

number 1, 2000, pp25-43.
Hank, T. C. and Kanamori, H, 1979. A moment magnitudetectonic deformation along the Sumatran fault fromscale, J. of Geophysics Res., Vol. 84,2348-2350.

triangulation and global positioning system surveys, J.
of Geophysical Research, 105, 28, 343-363.

Harmsen,S., Perkins, D. and Frankel, A, 1999. Deaggre-

Robert Hall and Wim Spakman. 2002. Subducted slabs

gation of probabilistic ground motion in central and69

R. RAHMAT PUTRA, J. KIYONO, Y. ONO, H. RAM PARAJULI

beneath the Eastern Indonesia-Tonga region: insights

relationship between modified Mercalli Intensity andfrom tomography, J. Earth and Planetary Letters 201

Engineering ground-motion parameters in Greece,(2002) 321-336.

Bull. Of the Seismological Society of America, vol.98,
No.4, pp.1863-1875.

Standar Nasional Indonesia (SNI 2002) 03-1726-2002. Per-Utsu, T. 1992, Catalog of destructive earthquake in theencanaan struktur beton bertulang tahan gempa, ISBN:world 1500-1992, In the Disaster Reduction Hand-

979-8897-04-8.

book, International Institute of Seismology and Earth-

Stepp, J.C, 1972. Analysis of completeness of earthquake

quake Engineering, pp, 1-24.

sample in the Pudet Sound area and its effect on statistical estimates of earthquake hazard, Proceedings ofYoung, R.R., Chiou, S. J. Silva, W. J. and Humphrey, J. R.

the first microzonation conference, Seattle, WA, 897-

1997. Strong ground motion attenuation relationship909

for subduction zone. Seimol. Res. Lett. 68, 58-73.

Tselentis G-Akis and Laurentiu Danciu, 2008. Empirical70