Risk Returns

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referring to IBC 2009 will be incorporated. These efforts

are part of the disaster risk reduction (DRR) process in

Indonesia following recent major earthquake disasters.

Engineering practice

Except in large cities, compliance with the building

code is currently a big issue. Theoretically, this code

should be enforced through the enactment of local

building regulations by local government authorities

in Indonesia. Local building authorities are responsible

for overseeing the implementation of building regula-

tions, including the building code, through a building

permit system, but lack of capacity of local governments

has hampered the effective implementation of the code.

Only Jakarta, the capital city of Indonesia, is consid-

ered to have good practice in enforcing the building

permit system, with relatively good earthquake-resist-

ance engineering construction practice for high-rise

buildings through an independent building authority

committee reporting directly to the Governor. Many

other big cities critically need better building design

and construction enforcement and practices, and better

building administration and monitoring systems.

For engineered constructions (structures built

with engineers’ intervention) such as public and

private high-rise buildings, compliance is not gener-

ally a problem as engineering consultants are always

involved as a standard procedure. On the other hand,

for non-engineered structures (those built without

the intervention of engineers) such as houses and

low-storey residential and public buildings (schools,

local health centres, worship facilities), there are

seismometers have been installed in different periods (for example,

three and six components, short-period Z components, long-period

3 components, broadband type, strong motion). The great Indian

Ocean tsunami of 26 December 2004 has prompted various institu-

tions from different countries to develop the Indian Ocean Tsunami

Early Warning System, which depends on a dense seismic monitor-

ing network supported by the installation of more telemetric-based

equipment including accelerometers, which are connected to

communication satellite systems. The whole system is operated by

the national Meteorological, Climatological and Geophysical Agency

(BMKG). Presently, the virtual seismic network for the Indian Ocean

available at BMKG consists of about 230 stations.

Development of the Indonesian seismic hazard map and

seismic building codes

The 1970 loading code was based on a zoning map developed in

1962.

The loading code was updated in 1981, based on a 1978

study.

It was subsequently updated in 1987 and 1989 as a national

standard for seismic design of buildings, based on a 10 per cent

probability of exceedance (PE) in 25 years (200-year earthquake

return period). The current Indonesian seismic hazard map for

buildings, released in 2002, adopted a 10 per cent PE in 50 years

(475-year earthquake return period).

Considering the seismo-tectonics of the current map, it is

understood that many earthquake source zones (subduction and

shallow crustal faults) need to be considered with more up-to-date

maximum magnitude potential based on recent research findings.

In addition, more recent ground motion models must be adopted.

Following a series of strong earthquake occurrences, revision of the

current building codes is now in progress and it is proposed that

new Indonesian seismic building codes will adopt a two per cent PE

in 50 years hazard map. In addition, a performance-based concept

Tsunami damaged area in Meulaboh Aceh, 2004

Image: Krishna S Pribadi