Ash could darken Singapore skies one day

Several volcanoes in region, but no big eruptions anticipated
Victoria Vaughan, Salim Osman in Jakarta & Alastair McIndoe in Manila
Straits Times 22 Apr 10;

A VOLCANIC ash cloud like the one that disrupted air traffic over Europe could form here someday, experts say.

'There are quite a few volcanoes in the region that could erupt that much ash, but we don't know of any big eruptions brewing in the immediate future,' said Professor Chris Newhall, volcano group leader at Nanyang Technological University's Earth Observatory Singapore (EOS).

Singapore is near the Pacific Ring of Fire, the range of volcanoes that skirts the Pacific Plate from New Zealand across Indonesia, through the Philippines and Japan, and down the coasts of North and South America.

Climatologist Matthias Roth at the National University of Singapore said that given Singapore's location, the possibility of an ash cloud here cannot be excluded. The wind direction and the location and size of the eruption are crucial factors.

'However, Singapore's frequent rainfall would work to mitigate any impact, unless the eruption were to occur during an unseasonably dry period,' he said.

A National Environment Agency (NEA) spokesman said: 'It is possible for Singapore to be affected if prevailing winds blow the ash cloud from eruptions in neighbouring countries towards us.'

This happened when Mt Pinatubo in Luzon Island, the Philippines, erupted in 1991. 'The air quality went into the moderate range for three days,' he said. 'The ash cloud remained in the upper atmosphere and spread around the world for many months following the eruption.'

Air travel from Singapore carried on, but at least 20 commercial aircraft were affected by encounters with ash clouds.

In fact, two planes lost engine power, according to a report by the Philippine Institute of Volcanology and Seismology (Philvolcs) and two American geological institutions.

Indonesia and the Philippines both have systems in place for aviation and civilian safety during volcanic eruptions.

'Each time there is an eruption, we monitor how far the volcanic ash is being blown and at what level,' said Dr Surono of Indonesia's Volcanology and Geology Centre in Bandung. 'We would issue an alert to all aircraft flying into our airspace to stay clear of the area.'

Reports of seismic activity and volcanic eruptions in Indonesia are relayed to the Volcanic Ash Advisory Centre in Darwin, Australia, which then advises the international aviation industry of the location and movement of volcanic ash clouds. The centre covers Indonesia, Papua New Guinea and parts of the Philippines.

Dr Surono said Indonesia last experienced a volcanic ash scare in June 1982, when a British Airways Boeing 747, flying to Australia from Malaysia, flew over the erupting Mt Galunggung in West Java.

'The aircraft's four engines were shut down within minutes,' he said.

The plane plunged about 20,000 feet (6,000m) before the crew could restart the engines and land the plane safely in Jakarta. Reports said a Singapore Airlines Boeing 747 also lost power in three of its four engines when it hit ash from the same eruption a few days later, but also landed safely.

In the Philippines, Philvolcs has observatories on all 23 active volcanoes in the country. It also reports to the Australia centre when a volcano erupts.

'That is the standard operating procedure even when the volcanic activity is quite minor,' said Mr Jaime Sincioco, its officer in charge of volcano monitoring.

Based on Mt Pinatubo's eruption history, Philvolcs believes the chance of renewed activity is unlikely for generations.

But EOS's Prof Newhall, 61, said predicting eruptions is not an exact science. Typically, predictions can only be made days, weeks or possibly months ahead.

He added EOS scientists are studying volcanoes across the region to gather data to help better understand the process.

'We are good at picking up signs that a volcano could erupt,' he said. 'But more work needs to be done.'