seismic hazard map

5/24/2018 Seismic Hazard Map

1/8

Proceeding the 6th Civil Engineering Conference in Asia Region: Embracing the Future through

Sustainability

ISBN 978-602-8605-08-3

DEVELOPMENT OF SEISMIC HAZARD AND RISK MAPS FORNEW SEISMIC BUILDING AND INFRASTRUCTURE CODES IN

INDONESIA

Masyhur Irsyam1, Wayan Sengara1, Fahmi Aldiamar1, Sri Widiyantoro1, WahyuTriyoso1, Danny Hilman1, Engkon Kertapati1, Irwan Meilano1, Suhardjono1, M.Asrurifak1, M. Ridwan1, Daniel Hutabarat2, Indra Jati Sidi2, and Widiadnyana

Merati21Team for Revision of Seismic Hazard Maps of Indonesia,

2Civil Engineering ITB

EXTENDED ABSTRACT

INTRODUCTION

The current Indonesian seismic hazard map contained in the latest Indonesian Earthquake Resistant

Building Code SNI 03-1726-2002 was issued in 2002 and developed by partially adopting the concept of

UBC 1997 (Figure 1). Since it was published, several great earthquakes occurred in Indonesia. A massive

earthquake occurred in 2004, for example, within 150 kilometers of Aceh Province that followed by a

massive tsunami have increased public and government awareness regarding seismic activities in

Indonesia. It triggered several researchers in earthquake engineering to consider the new conceptualapproach and technological shift as shown in the transition of UBC 1997 to IBC 2000 which evolved

further to IBC- 2009 and the latest ASCE 7-10 into national standard.

Fig. 1:Map of peak ground acceleration at bedrock (SB) of Indonesia inSNI 03-1726-2002

In 2009 the Ministry of Public Works then decided to establish a team to revise the current seismic hazard

maps of Indonesia. The main outcome of the research was the new seismic hazard maps of Indonesia for

revision of national standards. The maps incorporated total probability theorem and deterministic

approach supported by the latest geological and seismological data. Moreover, seismic hazard parameterswere derived from published journals, proceedings, previous researches, and latest information obtained


2/8

M.Irsyam et al.

K-33

during this study. It utilized the earthquake catalog, geological and seismological information of active

faults as new earthquakes source parameters. This catalog covered earthquakes from 1900 to 2009,

relocated catalog by the year 2005, and area between 90oE to 145

oE longitudes and 15

oS to 15

oN latitudes.

Deterministic hazard for subduction and fault zones and probabilistic hazard for several return periods of

earthquakes ground motions at bed rock of Indonesia were calculated. Maps of Maximum Considered

Earthquake Geometric Mean (MCEG) PGA, Risk-adjusted Maximum Considered Earthquake (MCER) for0.2s and 1.0s spectral response acceleration were also developed for new earthquake resistance buildings

code of Indonesia. This paper then presents development of the hazard maps of Indonesia that is

summarized from previous studies conducted by Irsyam et al (2008), Irsyam et al (2009), Irsyam et al

(2010a), Irsyam et al (2010b), Sengara et al (2010), Irsyam et al (2011), and Irsyam et al (2013).

SEISMOTECTONIC MODELS

There are three seismic source models used in this analysis; fault zone, subduction zone, and gridded

seismicity. The source models were derived using seismogenic conditions, focal mechanisms and

earthquake catalogs. This seismogenic conditions include geometry and geomorphological of tectonic

plate such as faults and subduction zones.

Fault source is treated as a plane in 3-D space for calculation of distance from a site to a certain point at

the plane. Parameters of fault required for input of PSHA include fault traces, focal mechanism, slip-rate,dip, length and width of the fault. Location of each fault was determined based on information obtained

from previous publications and relocated epicenters. The information was then used to trace each fault on

the Shuttle Radar Topographic Mission (SRTM) that indicates geomorphology. Using this procedure,

coordinate and length of each fault can be obtained. Other input data required for analysis was obtained

from publications and technical discussions among team members that consist of experts from geology,

geophysics, geodynamics, seismology, and geotechnique (Irsyam et al, 2010a). Figure 2 summarizes

maximum magnitude and slip-rate of fault sources in Indonesia.

Subduction sources were modeled based on well-identified seismotectonic data. Parameters of the sources

include the location of subduction in latitude and longitude coordinates, slope of subduction plane (dip),

rate, and b-value of the subduction zones that can be obtained from historical earthquake data, and limit

depth of subduction zones. The subduction source models were limited to 50 km and commonly

described as Megathrust or interface zones. Earthquake events occurred below Megathrust zones (Benioff

zones) are considered as deep background sources. Subduction earthquake sources are MegathrustAndaman-Sumatra segment, Nias Megathrust segment (Mid-1) Sumatra, Siberut Megathrust segment

(Mid-2), Sumatra, Java Megathrust segment, Megathrust Sumba segment, Timor Megathrust segment,

Megathrust Banda Sea segment, North Sulawesi Megathrust segments, and Megathrust Philippines

segment. The value of maximum magnitude, a-b value, and historical Mmaxfor the interface subductionsources as input parameters for subduction of Indonesia can be seen in Figure 3.


3/8

M.Irsyam et al.

K-34

Fig. 2: Maximum magnitude and slip rate of influenced seismic source

(Irsyam et al, 2010a and Irsyam et al, 2013)

Fig. 3:Segmentation model and parameter used in subduction Megathrustzone ofIndonesia (Irsyam et al, 2010a)

Gridded (smoothed) seismicity model are used to estimate the rate of occurrence of small earthquakes on

mapped faults and random earthquakes on unmapped faults (Petersen et al., 2008). This model is used to

predict the likelihood of bigger earthquake for region in which lack of seismogenic data but has seismic

activities report from small to moderate earthquakes. Therefore, this model is very suitable to be applied

on unmapped faults, but have historical earthquake records. The composite catalog was used as input for

background seismicity. It was divided into five depth intervals, i.e. shallow earthquakes (0-50 km),

intermediate earthquakes (50100 km and 100150 km), and deep earthquakes (150200 km and 200

300 km) (Irsyam et al, 2010a, Irsyam et al, 2010b and Irsyam et al, 2011).


4/8

M.Irsyam et al.

K-35

ATTENUATION FUNCTIONS

Due to insufficient PGA data needed to derive an attenuation function in Indonesia region, therefore, the

use of attenuation functions derived for other regions cannot be avoided. The selection is based on the

similarity on geologic and tectonic conditions where the attenuation functions were developed. Most of

the attenuation functions used in this study are Next Generation Attenuation (NGA) which were derivedusing worldwide historical earthquake data. The attenuation functions used in seismic hazard analysis for

each seismic source model are listed below (Irsyam et al 2010a, Irsyam et al, 2011, and Irsyam et al,

2013):

a. Shallow crustal sources, forfaultand shallow background sources model:(1) Boore-AtkinsonNGA (Boore dan Atkinson, 2008)(2) Campbell-BozorgniaNGA (Campbell dan Bozorgnia, 2008)(3) Chiou-Youngs NGA (Chiou dan Youngs, 2008)

b. Interface Subduction (Megathrust) sources, for subduction model:(1) Geomatrix subduction(Youngs et al., SRL, 1997)(2) Atkinson-Boore BC rock and global source subduction (Atkinson dan Boore, 2003)(3)

Zhao et al., with variableVs-30. (Zhao et al., 2006)

c. Benioff sources (deep intraslab), for deep background sources model:(1) AB intraslab seismicityCascadia regionBC-rock condition (Atkinson-Boore, Cascadia 2003)(2) Geomatrix slab seismicity rock, 1997srl.July 25 2006 (Youngs et al., 1997)(3) AB 2003 intraslab seismicity worldwide data region BC-rock condition (Atkinson-Boore,

Wordwide 2003)

DEVELOPMENT OF NEW SEISMIC HAZARD MAPS

The team has developed deterministic hazard maps for subduction and fault zones and probabilistic maps

for several return periods of earthquakes ground motions at bed rock of Indonesia. Maps of Maximum

Considered Earthquake Geometric Mean (MCEG) PGA, Risk-adjusted Maximum Considered Earthquake

(MCER) for 0.2s and 1.0s spectral response acceleration were also developed for revision of earthquakeresistance buildings code of Indonesia SNI 1726-2012.

In order to compare the hazard level after revision with the map contained in SNI-2002, new probabilistic

map with same hazard criteria is evaluated. The result shows significant differences of PGA value after

revision especially for location near active faults. The increase of PGA values is affected by the increase

of maximum magnitudes and other input parameters and by utilizing 3-D earthquake source model. For

example, in SNI-2002, the PGA level at bedrock in Semarang was 0.15 g whereas in the latest map it is

0.20-0.25 g. In Yogyakarta, the previous map show PGA level was 0.15 g whereas it would be 0.25

0.30 g after revision. Significant difference is also shown in Bandung where it was 0.15 0.20 g and it

become 0.300.40 g. This results suggests that continuous updating of hazard maps is required.

The team has developed seven probabilistic seismic hazard levels to represent 50, 100, 200, 500, 1,000,

2,500, and 10,000 years return periods of earthquakes and two deterministic hazard maps for subduction

and fault zones. New Indonesian code for building, SNI 1726-2012, follows the concept of MCEGused by

ASCE 7-10 for the purpose of geotechnical calculation. It combines both the results from probabilisticseismic hazard analysis for 2% probability of exceedance in 50 years (2,500 years earthquake) and

deterministic seismic hazard analysis for area located near active fault. Both approaches are utilized

according to the procedure proposed by Leyendecker et al (2000) as shown in Figure 4. The result ofcombining both probabilistic and deterministic analyses is called MCEG (Maximum Considered

Earthquake Geometric Mean) and is presented in Figure 5.


5/8

M.Irsyam et al.

K-36

Fig. 4:The concept of MCE as the result for near-fault criteria (Leyendecker et al,2000)

Fig. 5:Map of Maximum Considered Earthquake Geometric Mean (MCEG) atbedrock (SB) of Indonesia in SNI 1726-2012

In order to evaluate the seimic hazard for low and high risk structure (e.g. building), the spectral

acceleration maps are required. The team has developed the 0.2s and 1.0s spectral acceleration maps by

taking into account the probability of collapse for a structure. Probability of collapse of a structure isinfluenced by the structural capacity that has uncertainty. The uncertainty that includes as site-to-site

variability in the shape of hazard curve, material properties, nonstructural components, etc. will result in a

lack of uniformity in structural capacity (Luco, 2006). In the new Indonesian seismic design code, thisaspect is adopted in line with international codes (e.g., ASCE 7-10, IBC 2012).

The structural capacity of a structure is not easy to determine due to its uncertainty, therefore it is logical

to express it as a probability distribution. A common probability distribution for structural capacity is the

lognormal distribution that parameterized by a logarithmic standar deviation (Luco, 2006). Once the

probability distribution have been developed, the new concept of risk-targeted ground motion as new

value to represent the probability of collapse (P[Collapse]) is possible to determined.

The P[Collapse] at a certain coordinate principally is the risk-integral of the product from the seismic

hazard curve and the probability distribution of structural capacity at that coordinate over all the

acceleration value. For the new national standard, P[Collapse] was targeted in advance to be equal to 1%

in 50 years probability of collapse according to ASCE 7-10. Once the targeted probability of collapse is

determined, the iteration process over the integration calculation is performed to obtain a particular value

of acceleration denoted as Risk-Targeted Ground Motion (RTGM). All the RTGM value from every


6/8

M.Irsyam et al.

K-37

coordinate in Indonesia is then mapped into a Risk-Targeted Maximum Considered Earthquake (MCE R)

maps as shown in Figure 6 for and Figure 7.

MCER is intended to provide the spectral acceleration value as the hazard spectrum to do the responsespectra analysis for low to high risk building. Procedures to obtain the response spectra at the surface

follows international codes such as ASCE 7-10 or IBC 2012.

Fig. 6: Map of Risk-Targeted Maximum Consider Earthquake (MCER) at bedrock

(SB) of Indonesia at 0.2s Spectral Response Acceleration in SNI 1726-2012

Fig. 7: Map of Risk-Targeted Maximum Consider Earthquake (MCER) at bedrock (SB) of

Indonesia at1.0s Spectral Response Accelerationin SNI 1726-2012

CONCLUSIONS

Probabilistic and deterministic maps for estimation of seismic hazard in Indonesia have been developed

based upon updated available seismotectonic data, implementing new fault models, incorporating new

ground-motion prediction equations as Next Generation Attenuation (NGA), and dividing seismic sources

into fault, subduction, and background zones. Maps of Maximum Considered Earthquake Geometric


7/8

M.Irsyam et al.

K-38

Mean (MCEG), Risk-adjusted Maximum Considered Earthquake (MCER) for 0.2s and 1.0s spectral

response acceleration have also been produced for the new earthquake resistance building code SNI 1726-

2012.

ACKNOWLEDGEMENTS

The authors gratefully acknowledge the Ministry of Public Works, the Ministry of Research and

Technology, National Disaster Management Agency (BNPB) through AIFDR (Australia-Indonesia

Facility for Disaster Reduction ), and USGS for their supports and assistances during this study.

REFERENCESASCE (2005a), Minimum Design Loads for Buildings and Other Structures (ASCE Standard 7-05,

Including Supplement No. 1), American Society of Civil Engineers, Reston, VA.

ASCE (2010). Minimum Design Loads for Buildings and Other Structures (ASCE Standard 7-10,

Including Supplement No. 1), American Society of Civil Engineers, Reston, VA.

Atkinson, G.M., dan Boore, D.M. (2003). Empirical Ground-Motion Relations forSubduction-Zone

Earthquakes and Their Application to Cascadia and OtherRegions,Bulletin of the Seismological Societyof America, Vol. 93, No. 4, pp 1703-1729.

Atkinson, G., dan Boore, D. (1995). New Ground Motion Relations for Eastern North America, Bull.

Seismol. Soc. Am. 85, 1730.

Boore, D.M., and Atkinson, G.M. (2008). Ground-Motion Prediction Equations for The Average

Horizontal Component of PGA, PGV, and 5%-damped PSA at Spectral Periods Between 0.01 s and 10.0

s: Earthquake Spectra, v. 24, no. 1.

Campbell, K.W., and Bozorgnia, Y., (2008). Ground motion Model for The Geometric Mean Horizontal

Component of PGA, PGV, PGD and 5% Damped Linear Elastic Response Spectra for Periods Ranging

from 0.01 to 10.0 s: Earthquake Spectra, v. 24, no. 1.

Chiou, B., and Youngs, R., (2008). A NGA Model for The Average Horizontal Component of Peak

Ground Motion and Response Spectra: Earthquake Spectra, v. 24, no. 1.

Cornell, C.A. (1968). Engineering Seismic Risk Analysis, Bulletin of the Seismological Society of

America, Vol. 58.

Irsyam, M., Dangkua, D.T., Hendriyawan, Hoedayanto, D., Hutapea, B.M., Kertapati, E., Boen, T.,

Petersen, M.D. (2008). Proposed Hazard Seismic Maps of Sumatera and Java Islands and Microzonation

Study of Jakarta City, Indonesia,Journal of Earth Science System, 117, S2, November.

Irsyam, M., Asrurifak, M., Hendriyawan, Budiono, B., Triyoso, W., Merati, M., Sengara, I.W., and

Firmanti, A., (2009).Development of Spectral Hazard Map for Indonesia Using Probabilistic Method by

Considering Difference Values of Mmax for Shallow Background Sources, The 1stInternational Seminar

on Sustainable Infrastructure and Built Environment in Developing Countries, Bandung, November.

Irsyam, M., Sengara, I.W., Asrurifak, M., Ridwan, M., Aldiamar, F., Widiyantoro, S., Triyoso, W.,

Natawijaya, D.H., Kertapati, E., Meilano, I., and Suhardjono (2010a). Summary: Development of Seismic

Hazard Maps of Indonesia for Revision of Seismic Hazard Map in SNI 03-1726-2002, reseach report

submited to the Ministry of Public Works by Team for Revision of Seismic Hazard Maps of Indonesia,

July.

Irsyam, M., Asrurifak, M., Hendriyawan, Budiono, B., Triyoso, W., and Firmanti, A., (2010b).

Development of Spectral Hazard Maps for Proposed Revision of Indonesia Seismic Building Code,

Geomechanics and Geoengineering an International Journal,Vol. 5. No. 1.

Irsyam, M., Hendriyawan, Asrurifak, M., Razali, R., Fermanti, A. (2011). Combined Hazards: Seismic

Hazard maps of Indonesia and Geotechnical and Tsunami Hazard Assessment for Banda Aceh,Chapter 8

of Geotechnical and Earthquake Geotechnics towards Global Sustainabilityedited bySusumu Iai, ISBN978-94-007-0469-5, Springer.


8/8

M.Irsyam et al.

K-39

Irsyam, M., Hendriyawan, Asrurifak, M., Ridwan, M., Aldiamar, F., Sengara, I.W., Widiyantoro, S.,

Triyoso, W., Natawijaya, D.H., Kertapati, E., Meilano, I., Suhardjono, and Firmanti, A. (2013). Past

Earthquakes in Indonesia and New Seismic Hazard Maps for Earthquake Design of Buildings andInfrastructures, Chapter 3 of part 1 of Geotechnical Predictions and Practice in Dealing with

Geohazards edited by Chu, Jian, Wardani, S.P.R., and Lizuka, A., due April 2013, ISBN 978-94-007-

5674-8, Springer.

Luco, N. (2006). Risk-Targeted Approach to Selecting Return Periods for Design Maps,Proceedings of

the 3rd ATC-35/USGS National Earthquake Ground-MotionMapping Workshop, Applied Technology

Council, Redwood City, CA

Leyendecker, E.V., Hunt, R.J., Frankel, A.D., and Rukstales, K.S. (2000). Development of Maximum

Considered Earthquake Ground Motion Maps, Earthquake Spectra, Volume 16, No. 1., pp. 21-40.

Petersen, M.D., Mueller, C. S., Frankel, A.D., Zeng, Y., (2008). Spatial Seismicity Rates and Maximum

Magnitudes for Background Earthquakes, USGS Open-File Report.

Sengara, I.W., Irsyam, M., Asrurifak, M., Ridwan, M., Aldiamar, F., Widiyantoro, S., Triyoso, W.,Natawijaya, D.H., Kertapati, E., Meilano, I., and Suhardjono (2010). Development of Seismic Hazard

maps of Indonesia for Revision of Hazard Map in SNI 03-1726-2002 , Reseach report submitted to the

Australia-Indonesia Facility for Disaster Reduction (AIFDR), October.

Youngs, R.R., Chiou, S.J., Silva, W.J., dan Humphrey, J.R., (1997). Strong Ground Motion Attenuation

Relationships for Subduction Zone Earthquakes. Seismol. Res. Lett. 68, 5873.

Zhao John X., Zhang, J., Asano, A., Ohno, Y., Oouchi, T., Takahashi, T., Ogawa, H., Irikura, K., Thio,

H., dan Somerville, P., (2006).Attenuation Relations of Strong Motion in Japan Using Site Classification

Based On Predominant Period, Bull. Seismol. Soc. Am., 96, 898.

seismic hazard map

Documents