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©New Sunday Times (Used by permission)
by Chai Mei Ling, Elizabeth John and R. Yasothai

Why we need to worry

Malaysia is inching closer to rumble zones and will not be immune to earthquakes forever. Work is under way to prepare us for the next big shake-up, report Chan Mei Ling, Elizabeth John and R. Yasothai

WE are only 350km away from the closest active fault line in Sumatra, the same distance separating Johor Baru from Kuala Lumpur.

Year after year, neighbouring tectonic plates inch towards ours from all directions. Putrajaya and Klang are sitting on the kind of soil most susceptible to tremors.

And on every other day, new fault lines are unearthed in Sabah. Still think of Malaysia as safe from earthquake threats?

The pinball effect

THERE’S every reason to worry about earthquakes, said Universiti Teknologi Malaysia Associate Professor Dr Azlan Adnan.

"Although Malaysia is located on the stable Sunda plate, pressure on the continent is mounting because the Australian, Eurasian and Philippine plates around us are moving and pushing into us.

"To relieve this stress, cracks occur on the surface. As the pressure intensifies, cracks are more frequent and bigger," said Azlan, who heads UTM’s Structural Earthquake Engineering Research.

According to Azlan, the major Aceh earthquake in 2004 had disturbed the surrounding plates.

The plates are moving closer towards the Sumatran fault line and a shift of a few centimetres towards the west was recorded after the incident.

"We are now closer to the epicentre. In the event of an earthquake, the pressure will be greater," he said at a recent national seminar on earthquakes.

There is some disagreement over these findings.

"Yes, we are stuck in the middle, pushed around by plates from all sides like a pinball, but this happens slowly," said Alexander Yan, director of Sabah’s Mineral and Geoscience Department.

He doesn’t believe the pressure is so great or that we are nearer to the Sumatran fault line. The Sunda plate is still very stable.

But there is one exception and this is Sabah, which has experienced the most earthquakes — 78 in the last century.

Sabah still has many active young faults and rock formations and its rocks are only 150 million years old, making them new kids on the block in geological terms.

Compared with formations in the peninsula which are 500 million years old, these tertiary rocks are still unstable, said Yan.

We can never be too careful

WHEN high-magnitude earthquakes shook Aceh in 2004, Nias in 2005 and Sumatra last March, tremors rocked our shores.

Although Peninsular Malaysia has recorded few cases of serious building damage from tremors, this scenario could no longer be ruled out, speakers concluded.

Their main concern was the impact on public safety. This could vary, depending on how close we are to the epicentre of a quake, soil condition and the type of construction, said Azlan.

Strong earthquakes could cause severe damage in areas up to 400km away from its epicentre, said seismological division director of the Meteorological Department Dr Mohd Rosaidi Che Abas.

This puts Malaysia — about 350km away from the Sumatran fault line — at risk.

Malaysia is also only 700km from another trouble zone, off Sumatra’s west coast, where the 2004 earthquake and tsunami originated.

Soil condition is crucial in determining the severity of an earthquake. Wetlands and soft soil, for instance, tend to amplify vibrations.

In Kuala Lumpur and Putrajaya, which sit on soft soil, underground motions were amplified by up to 2.6 times on the surface.

For this reason, Yan said the Sabah government should reconsider plans to construct the Palm Oil Industrial Cluster (POIC) on reclaimed land near Lahad Datu.

Any structure built there would lie on non-consolidated alluvium — loose soil with sand-like consistency.

With the excessive shaking caused by tremors, the soil changes into a state where it can flow in a process called liquefaction.

And when solid ground turns to jelly, it is unable to withstand the weight of the building and could induce landslides and sinkholes.

An example was the discovery of 50 sinkholes in Ipoh a few months after the Aceh earthquake.

Not all buildings in Malaysia are quake-resistant. They are also becoming more complex and have irregular designs that make them susceptible to tremors.

Ceilings and partitions in low-rise buildings could give way when a low magnitude earthquake rumbles in a neighbouring country.

Malaysia does not have any standards or guidelines for making buildings, bridges and public transport quake-safe.

Counter measures

THREE per cent of the building’s weight. That’s the amount of horizontal force the ground structures can withstand before they collapse.

The government wants to increase that threshold to a minimum of 10 per cent. It has put this down in the draft handbook On seismic design guidelines for concrete buildings in Malaysia.

The goal is to avoid a collapse of buildings.

"As long as buildings don’t collapse and people can evacuate the premises, it’s good enough. Our objective is to save lives by buying time," Azlan said.

The draft guideline will provide some guidelines to the construction sector over efforts to incorporate seismic designs into the country’s infrastructure.

Doubling a building’s ability to resist an earthquake’s force would increase structural cost by up to 10 per cent, said engineer Dr Abdul Majid Abu Kassim.

As a result, total building cost could increase by 2.5 per cent, said Majid, who represented the Association of Consulting Engineers Malaysia Council at the seminar

High or low cost, Malaysia has no option but to be prepared.

"So far, no life has been lost from the collapse of buildings due to tremors in Malaysia. But we’re not taking chances," said Azlan.

Rosaidi said the absence of major earthquake disasters in Malaysia should not be an excuse to dismiss earthquake threats.

"Earthquakes don’t kill people, unsafe buildings do."

Making buildings quake-safe

THE crushing Sumatran earthquake and the resulting tsunami of 2004 raised one important question for Malaysia: How safe are buildings against the rattle and roll of mighty earth movements?

Long comfortable in the knowledge that we sit in a stable zone, few realise just how close the country is to trouble — the epicentre of the 6.6 magnitude earthquake off Sumatra last March was just 88km from Seremban.

So for the past two years, several government agencies, universities and engineers in Malaysia have been trying to find out how vulnerable buildings are to seismic forces.

At the same time, they have been mapping out ground movements from earthquakes originating in Indonesia. The data was to enable local professionals to design buildings that are quake-resistant.

A team led by the Public Works Department (PWD), recently studied the vulnerability of 26 selected public buildings in the country.

Sixty-five buildings were initially chosen for the study but only 26 were selected because they came out with lower scores during a screening process.

The low score indicated that they might be more susceptible to displacement during tremors and were therefore, more critical for the study.

Among them were the National Registration Department building in Putrajaya, Kota Baru Hospital and the Fire and Rescue Department quarters in Miri.

Their findings showed that under the maximum earthquake forces Malaysia is expected to face, the buildings would not suffer significant structural damages.

They would still retain nearly all of their pre-quake strength and stiffness, and may still be used, said engineer P.N. Selvanayagam, when he presented the findings at the recent national seminar on earthquakes.

"Based on current building standards and the kind of earthquake-related tremors we’ve experienced, this study gives some comfort that our buildings will be safe provided they have been well maintained and constructed.

"The study has also produced seismic hazard maps which give ground movement values according to zones in Malaysia."

Selvanayagam, who is the department’s deputy director-general III said several initiatives were being taken by PWD, other government agencies and universities to monitor and review the developments.

In Malaysia, reinforced concrete buildings have been designed according to the BS8110 code of practice, which does not have specific provisions for seismic forces.

The Uniform Building by-laws makes references for the consideration of seismic forces in the building design but does not state what values and measures should be used.

Studies like this are meant to help consultants use locally developed parameters in their design assessments and help keep buildings steady during the next big earthquake.

National search for answers

MEXICO City. 1985.

An 8.1 magnitude earthquake 400km away from the booming city triggered severe destruction because seismic waves were amplified by the soft soil.

Substantial parts of major cities like Kuala Lumpur are built over soft soil. So how big of a risk would Malaysia face?

It’s a question government agencies, universities and professional bodies are attempting to answer through a massive national study.
The study aims to investigate hazards and risks from tsunamis and earthquakes. Projects under the study range from simple data collection to modelling and mapping.

Led by the Academy of Sciences Malaysia, agencies will look into risks faced by hazardous installations like toxic waste disposal sites and liquified natural gas plants.

Also, problems that might plague highways, the LRT and water supply system in the event of an earthquake.

There are also projects to update earthquake intensity maps which will form the basis for safety requirements for high-rise buildings and critical infrastructure.

Risk maps are being prepared for areas prone to tsunamis generated in Sumatra, Philippines and the Sulawesi sea.

Known as the government’s "Seismic and Tsunami Hazard and Risks Study in Malaysia", this national effort will also see the development of a model for tsunami awareness and evacuation, which would be used nationwide by the National Security Division of the prime minister’s department.

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