Four volcanoes act up in tandem

Alert status raised to level two for Mount Bulusan

Manila housewife Gloria Gallego thinks that four volcanoes acting up at the same time is 'probably a sign that God is angry'. But Jaime Santos Sincioco, who has been watching volcanoes for 30 years, says the simultaneous rumblings are 'just a coincidence'.

Three months ago, Mount Bulusan, about 600km southeast of Manila, started rumbling. A fortnight ago, it began spewing out superheated ash in a plume that stretched 2km up into the sky.

Now more explosions - caused by water mixing with heated rocks - have occurred. The Philippine Institute of Volcanology and Seismology has raised its warning to alert level two around Mount Bulusan, indicating a hazardous eruption is likely.

At the same time, Mr Sincioco, the institute's supervising science research specialist, said alert level one status had been declared around three other volcanoes: Mayon in Albay province; Taal, about 70km south of Manila; and Kanlaon in the centre of Negros island in central Philippines. The first alert level indicates a volcano has become active.

'Volcanoes, even when near each other like Bulusan and Mayon, do not trigger the other to explode,' Mr Sincioco said, because each has its own system.

The Philippines is home to at least 330 known volcanoes. Mr Sincioco said the list might still grow as more areas are surveyed.

Some islands grew out of eruptions, he said, pointing to Camiguin in southern Philippines, which was formed from magma, or molten rock, spewed out by Hibok-Hibok. It was Hibok-Hibok's deadly eruption from 1948 to 1951 that led to the creation of the institute, he said.

The four volcanoes now acting up head the list of the 22 most active volcanoes.

Based on the institute's records, topping the list is Mayon with 44 known eruptions, followed by Taal with 33. Third is Kanlaon with 24 recorded explosions, and Bulusan is fourth with 12.

The institute maintains permanent monitoring stations in all four, and at Mount Pinatubo and Hibok-Hibok.

Mount Pinatubo's unexpected explosion in 1991 after 450 years of inactivity threw tonnes of gas and particles into the Earth's atmosphere. Scientists have since estimated that the volcanic eruption, the largest in the last century cooled Earth's climate by 0.3 degrees Celsius for about two years.

Taal, one of the world's smallest volcanoes, is among the deadliest and the trickiest to monitor. Its most violent explosion was in 1911, killing 1,335 people in an instant.

Mayon's most notable eruption was in 1814, when 1,200 people died.