Singapore faces negligible tsunami risks

Study shows that even if waves hit island, they will not be life threatening
Liaw Wy-Cin, Straits Times 17 Dec 08;

THE impact of any tsunami, triggered by quakes in the region, on Singapore would be minimal, according to a new two-year study.

Computer simulations used in the study found that it would take an earthquake, in Indonesian or Philippine waters, measuring about 9.0 on the Richter scale to generate a tsunami powerful enough to reach Singapore.

Even then, it would take 10 hours before the first waves hit the island.

By that time, the waves would be no more than 0.7m above the average sea level, reaching no more than 50m inland and at speeds slower than that of normal tides. From Straits Times PDF.

The National Environment Agency (NEA) commissioned the National University of Singapore (NUS) and Nanyang Technological University (NTU) to conduct the study in 2006.

The aim of the study was to discover the effects of tidal waves, caused by underwater earth movements, on Singapore.

This was in response to the Indian Ocean tsunami on Dec 26 four years ago, which killed more than 225,000 people. The epicentre of the earthquake that caused the tsunami was in the sea near Indonesia, known as the Sunda Arc.

This area, together with another area called the Manila Trench near the Philippines, was identified as a hot spot for underwater movement which could pose a tsunami threat to Singapore.

Earthquakes in the region usually measure 6.0 to 8.0 on the Richter scale, apart from the massive quake in 2004. There was also one measuring 8.7 in 2005 and only two measuring 8.5 to 9.0 in the 19th century.

The Richter scale goes up to 10 points. Earthquakes measuring about 8.0 occur once a year and can cause serious damage in areas several hundred kilometres from the epicentre.

Earthquakes at 9.0 on the Richter scale have devastating effects several thousand kilometres away and occur once in 20 years.

An earthquake measuring 10 on the Richter scale has never been recorded.

Earlier this month, NTU researchers said they had detected signs of an earthquake off the Indonesian island of Sumatra but could not predict when or where it would strike.

It is, however, unlikely to be as large as the 2004 one.

The shallow waters and land masses around Singapore protect the island from the effects of any tsunami, said Mr Foong Chee Leong, the director-general of NEA's meteorological services.

Even during the 2004 earthquake, there was no record of a rise in Singapore's sea level, he said.

The speed at which any tsunami wave would hit Singapore's shores - at half a metre per second - is slower than the speed of a normal tide, which is 1m to 2m per second, said one of the NUS researchers, Dr Pavel Tkalich.

The study costs $1.3 million and made use of a modified program used in Japanese tsunami warning systems, which are considered among the best in the world.

Six Singapore beaches were identified as potential risk areas: West Coast Park, Labrador Park, Sentosa, the Southern Islands, East Coast Park and Pasir Ris Park.

But these areas pose a limited threat because the nearest residential area from the coastline is about 80m inland and any built- up area was constructed at least 1.25m above the highest tide level of about 1.5m above the average sea level here, said Mr Foong.

Dean of NTU's college of engineering, Professor Pan Tso-Chien, said the only worry would be people on the beach.

'Those in the sea would feel like they are riding a wave, bobbing up and down,' he said.

'The waves, by the time they hit the beach would be less than 1m high, at very low speeds, and (they) wouldn't be able to cause any destruction.'

Response plan in place
Straits Times 17 Dec 08;

EVEN though the risk of a tsunami hitting Singapore is low, beaches here will still be evacuated and the public advised to stay away if the alert is sounded.

This is part of a tsunami response plan drawn up by the National Environment Agency (NEA) and other agencies, including the PUB and the Maritime and Port Authority of Singapore.

The lead time of the 10 hours it would take for the first of any tsunami waves to hit Singapore would provide ample time for a decision to be made on whether to sound the alarm and evacuate beaches, said Mr Foong Chee Leong, director-general of the NEA's meteorological services division.

He said the NEA receives alerts about earthquakes within two minutes of their occurrence.

It would take an hour for data to be analysed to ascertain if a tsunami would be generated and if it would reach Singapore.

Information about when it would do so, its speed, and height of the waves, for example, would also be available within the first hour of the earthquake alert.

Time to analyse the data is necessary to avoid sounding false alarms, said Mr Foong.

The NEA has identified six vulnerable beach areas - West Coast Park, Labrador Park, Sentosa, Southern Islands, East Coast Park and Pasir Ris Park.

In the event of a tsunami heading towards Singapore, advisories would be issued via the media.

The police and the Sentosa Development Corporation would then help to evacuate the public from these areas.

The NEA said the public warning siren will be activated only if the impact is expected to be severe, to avoid alarming the public unnecessarily.

Sheltered from the waves
Two-year study finds that landmasses and shallow waters protect Singapore from tsunamis
Esther Ng, Today Online 17 Dec 08;

IN THE worst-case scenario, waves would lap the waists of beachgoers should a tsunami hit Singapore. And residences would not be affected as flooding is only expected to affect areas less than 50 metres from the shore.

Since the 2004 Boxing Day tsunami caused havoc in the region, Singaporeans have wondered: Would we be as lucky the next time another tsunami struck?

Yes, according to a tsunami study commissioned by the National Environment Agency (NEA).

Even if a magnitude 9 earthquake were to occur in the Manila Trench (a tectonic plate in the South China sea) and the Sunda Arc, north-west of Sumatra island,Singapore would be safe because it is sheltered by relatively shallow waters and landmasses such as Sumatra and Peninsula Malaysia.

“By the time the tsunami waves arrive in Singapore, the wave energy will have largely been dissipated and the impact on Singapore will be minimal,” said Mr Foong Chee Leong, the director-general of the NEA’s meteorological services division.

However, the two-year study conducted by the National University of Singapore and Nanyang Technological University, at the cost of $1.3 million, found that some of our beaches are vulnerable to flooding from a tsunami triggered by a magnitude 9 earthquake at the Manila Trench. These are the West Coast Park, Labrador Park, Sentosa and Southern Islands, East Coast Park and Pasir Ris Park.

But the public has little to fear.

“Over the years, much of Singapore’s shoreline has undergone coastal hardening and is protected by sea walls and other reinforcement,” said an NEA spokesman.

“Most of Singapore’s industrial buildings and residences are built in areas which are elevated well above high tide levels. Hence, it is very unlikely for residences along Elias Road, Loyang Besar and the industrial buildings along Loyang Crescent will be affected by a tsunami.”

However, to date, there have been no records of earthquakes occurring in Singapore, only weak tremors which are felt occasionally from distant earthquakes off Sumatra. The agency said it will continue to monitor regional seismic activities for possible tsunamis, even though there has been no known records of tsunamis affecting Singapore.

No major impact from tsunamis: NEA study
Noor Aisha, Business Times 17 Dec 08;

THE National Environment Agency (NEA) has confirmed that there is a low probability of Singapore being affected by a tsunami, following a two-year study since August 2006.

The study considered two sources which might trigger tsunami that could affect Singapore: first, undersea landslides near Singapore and, second, seismic zones with the potential to produce great earthquakes of magnitude 9.0 and above.

According to the study, both sources do not pose a major threat as the likelihood of undersea landslides near Singapore is very low.

In addition, simulations by numerical models showed that tsunami triggered by earthquakes along seismic zones capable of producing such large earthquakes are expected to take more than 10 hours to reach Singapore's coast.

The research was jointly conducted by the National University of Singapore and Nanyang Technological University at a cost of $1.3 million.

Nonetheless, in the event of a tsunami, a Tsunami Response Plan has also been developed by the NEA, with the cooperation of relevant agencies like the Singapore Police Force, Maritime Port Authority, Jurong Town Corporation and Sentosa Development Corporation.

We are safe from killer waves
Tsunami waves would be only 50cm tall if they reach S'pore: study
Chng Choon Hiong, The New Paper 18 Dec 08;

FOR Singaporeans who are worried that a tsunami may strike our shores, here's good news: We are safe from killer waves.

A new two-year study has confirmed this.

The height of the tsunami waves if they do reach Singapore will be considerably less than the highest tide (1.5m) here.

In the worst case scenario where the first wave reaches Singapore during highest tide, the water will only move a maximum of 50m inland.

The study, which began in August 2006, was conducted by the National University of Singapore (NUS) and Nanyang Technological University (NTU).

It was commissioned by the National Environment Agency (NEA) in response to the 2004 Boxing Day tsunami which killed 225,000 people in 11 countries.

The study examines several extreme scenarios (see graphics) of powerful undersea earthquakes and landslides occurring in locations that may result in tsunami waves hitting our shores.

The researchers in the team ran computer simulations to determine the nature of the waves that would hit Singapore under such situations.

The simulations shows that the relatively shallow waters (less than 200m) surrounding Singapore are able to slow down and dissipate the enormous amount of energy carried by these monster waves.

The ample lead time of 10 hours - the estimated time for the waves to reach our shores - allows the authorities to keep track of the event, receive additional information and further improve their confidence on the assessment of the situation, said Professor Chan Eng Soon, Dean of Engineering at NUS.

Unprotected beaches

While the study has found that the impact of a tsunami is likely to be minimal for Singapore, people at unprotected beaches could still be exposed to some risk if the waves do hit us.

The list of unprotected beaches include West Coast Park, Labrador Park, East Coast Park, Pasir Ris Park, Sentosa and the Southern Islands.

Even though Singapore faces no significant threat from tsunamis, NEA has nevertheless developed a Tsunami Response Plan with the cooperation of several other agencies, such as the Singapore Police and Maritime Port Authority.