Think Singapore is safe from quakes?

Distance may not guarantee safety, going by past cases
Christopher Tan, Straits Times 12 Sep 08;

THE ceiling lamps sway, the window frames shudder and soon, occupants have evacuated and gathered on the ground floor.

It is a scene that has been unfolding with greater frequency here these days, and seismologist Michael Spranger has an explanation for it.

Between Dec 25, 2004 and March 31 this year, Sumatra accounted for 23 per cent of all quakes measuring 6.9 or stronger on the Richter scale. In the last 30 years or so, the region accounted for only 2 per cent of quakes worldwide.

Dr Spranger is an earthquake risk researcher at Munich Re, one of the world's largest reinsurers.

Like others in the business, Munich Re is calling on its clients, chiefly general insurers, to reassess their exposure to quake claims - in Singapore.

Reinsurers have been doing so since the frequency and intensity of tremors in Sumatra - a large Indonesian island just south of Singapore - spiked after 2004. In December that year, a 9.3 undersea quake off Sumatra spawned killer waves which claimed over 230,000 lives and caused billions in damage across half the world.Dr Spranger also pointed out that cities sited away from tremor-prone zones are not necessarily immune to the devastating effects of earthquakes.

He cited the case of Mexico City. 'In 1985, a quake occurred off the Mexican coast. About 300km away in Mexico City, buildings collapsed, and there were 10,000 fatalities.

'Between the coast and Mexico City, you didn't feel the earthquake.'

In Singapore's case, the Republic is vulnerable to certain shockwaves that can travel long distances, he said.

'Only the long waves arrive and they affect mostly high-rise buildings and especially those built on reclaimed land.

'In that respect, the risk has changed because Singapore has a lot more high-rise buildings on reclaimed land now.'

He said that these 'long waves' or low-frequency waves could 'amplify when they reach soft ground'.

Mexico City, he pointed out, is also partly built on reclaimed land.

But Singapore is unlikely to face the same level of damage that Mexico City did as it has a different make-up of base rock and soil and is farther away from quake zones.

'There would probably be many small, non-structural damages on a lot of buildings,' he said.

'You'll have windows falling down, ceilings falling down, computers destroyed, elevators having to be replaced... and maybe some structural damage, but that would be the exception.'

But that does not mean the financial impact would not be sizeable. Industry sources said an accumulation of small property damage can result in a substantial loss to one or more insurers.

That does not include business and economic disruption, personal injury and fatalities.

Mr Emil Bergundthal, executive committee member of the Singapore Reinsurance Association, said: 'Earthquakes have become a growing concern...of late. How reinsurers react to this development is pretty much up to the individual company.'

That Singapore may not be entirely safe from regional earthquakes is a proposition that has been raised before.

Researchers at the Nanyang Techological University (NTU) in a 1990s study concluded that the risk here was higher than expected; and that the building codes did not reflect this risk.

Professor T. C. Pan, dean of NTU's College of Engineering, and director of the Protective Technology Research Centre, said as much in a Bulletin of the Seismological Society of America in 1996.

Among 27 incidents recorded between 1833 and 1995 which caused ground motions in Singapore, 'six cannot be attributed' to any documented earthquake anywhere.

Some of the unexplained shaking was quite strong. 'For example, the tremor of Dec 28, 1948 lasted around 30 seconds and set a whole bungalow in distinct motion,' Prof Pan wrote.

If that tremor had been caused by a major earthquake far away from Singapore, then why was it not picked up by earthquake monitors in the region?

But if it had been caused by a weak earthquake close to Singapore, then it is time to review the assumption that earthquake hazard is not an issue for the Republic, Prof Pan noted.

Professor Kerry Sieh, founding director of NTU's six-month-old Earth Observatory, said Sumatra will be hit by 'the next big one...in the next 30 days or 30 years'.

'We have a geological record that goes back 1,000 years. It shows the region being hit by major quakes every 200-300 years,' he said. 'The last cluster of powerful quakes happened about 200 years ago. We're entering a new cluster.'

He noted that the major quakes which hit Sumatra last September and the subsequent tremors are part of a process leading to the 'next big one', which he said could be a quake as powerful as 8.8 on the Richter scale.

Quakes measuring 8 to 8.9 are classified as 'great' earthquakes, and can cause serious damage in areas several hundred kilometres away. On average, only one is recorded each year, out of tens of thousands of quakes big and small worldwide.

There are three potential areas in Sumatra where it could take place. Experts are most concerned about the one just north of Padang. At just over 400km from Singapore, a big quake there would be felt strongly here.

Besides Mexico City, Dr Spranger cited other examples of historically 'safe' cities hit by quakes.

One was the 1989 quake in Newcastle, Australia. Measuring 'only 5.5', it claimed at least 12 lives, injured 160 and cost the city financial losses of A$4 billion (S$4.6 billion) - of which A$1 billion were insured losses.

It was Australia's first fatal quake.

'That was the wake-up call for Sydney, and for Australia in general,' Dr Spranger said.

Another prime example was the quake in China's Sichuan province in May. Nearly 70,000 people died, 18,000 went missing, 375,000 were injured and about five million were left homeless.

Dr Spranger said this part of Sichuan had never been considered high-risk, compared to cities near other fault lines.

'This area that was affected is on the same class of expected shaking as Hong Kong, and probably Singapore,' he said.

A catastrophe expert with another major reinsurer, who did not wish to be named, said that more needs to be done before the level of risk facing Singapore can be ascertained.

'The difficulty we face is that there is only one quake-forecasting model applicable to Singapore, and it is very old. The last update of it was in the mid-1990s,' the expert said. 'But even if we had a relevant and updated model, we don't fully understand the science. Results from models can vary greatly.

'What is certain is that our buildings are not designed to withstand earthquakes. It is time everybody takes a good look at this.'

Singapore studies possible impact of quakes
Christopher Tan, Straits Times 12 Sep 08;

TWO new studies are under way to determine just how vulnerable Singapore is to earthquakes, despite long-held views that the island is immune to the devastating effects of nearby tremors.

More frequent and intense seismic activity in the region recently has sparked the studies.

Their results could affect building codes here, which currently do not require structures to be built to withstand quakes.

News of the studies here comes as two strong earthquakes rattled Japan and Indonesia yesterday morning.

The more powerful of the two, with a magnitude of 7.0, hit off Japan's northernmost main island of Hokkaido, the country's meteorological agency said.

North-eastern Indonesia was hit by a 6.6-magnitude quake that struck beneath the Molucca Sea, reported the US Geological Survey.

There were no reports of casualties or damage in both incidents.

Neither had any impact here too, unlike recent quakes in Sumatra which have resulted in some high-rise buildings swaying.

The Nanyang Technological University is involved in the two studies being undertaken here to find out if the effects felt in the Republic are likely to be more severe in future.

The Monetary Authority of Singapore is planning to part-fund one study on the possible impact that natural catastrophes would have on Singapore's financial sector, with earthquakes high on the agenda.

The second study, commissioned by the Building & Construction Authority (BCA), is part of its 'review of building codes and regulations after several major earthquakes in the region', said its spokesman Jeanna Das.

The 'earthquake vulnerability' study, which will be completed in one to two years, will also 'analyse how various buildings react during tremors'.

That the BCA has commissioned such a study is significant as it has always maintained that buildings here are safe from the effects of quakes in Sumatra because Singapore is far away from fault lines. It had added that Singapore had high standards governing construction.

The two nearest fault lines in Sumatra are 400km and 700km away, so the seismic waves would have weakened considerably by the time they reach Singapore.

But the frequency and intensity of recent seismic activity on the Indonesian island is worrying experts, who had previously believed that tremors were enough to make buildings sway, and no more.

In February alone, US scientists recorded nearly 20 ruptures along the fault line off Sumatra that spawned the 2004 Boxing Day tsunami.

Between Dec 25, 2004 and March 31 this year, Sumatra accounted for 23 per cent of all quakes measuring 6.9 or stronger on the Richter scale. In the last 30 years or so, the region accounted for only 2 per cent of quakes worldwide.

Already reinsurers, known for being well ahead of the curve when it comes to spotting new risks, have raised the alarm.

Munich Re and Swiss Re - the industry's two biggest players - have begun advising insurance companies to see if premiums need to reflect the potential risks of quake-related claims.

Mr Peter Zimmerli, Swiss Re's vice-president (property & specialty), said: 'For earthquake exposure, we have worked to create awareness that there are such exposures in Singapore and therefore, the need to quantify and price such exposures into the premiums.'

Mr Kua Ka Hin, chief executive of Munich Re's Singapore branch, concurred: 'Earthquake is not a non-issue anymore in Singapore. It is an issue of concern.'

For now, however, general insurers continue to provide property owners earthquake coverage free of charge as no one in the industry wants to be the first to do otherwise.

'In a competitive market, charging could mean a loss of business,' a General Insurance Association spokesman said.

Mr Kua said charging is not the only way. Insurers could also mitigate their exposure by transferring the risk to other insurers or reinsurers, transforming or structuring the risk to the capital market by using catastrophe bonds, restructuring of policies, pooling of similar type of risks of participating insurance companies, or simply minimising or curtailing coverage.

Over at the National University of Singapore's nine-month-old Centre for Hazards Research, Prof C. G. Goh is examining how tremors will affect not just high-rise buildings but underground structures here as well, such as MRT tunnels. He told The Straits Times: 'One should bear in mind that a big earthquake is a low-probability but high-consequence event.'

He added that based on the risk that the authorities are prepared to take, cost-effective and yet safe designs can be adopted to account 'for possible earthquake load'.

'It is not uncommon for building codes to be revised, if necessary, based on better understanding through years of research and also from actual events,' he said.