BACOLOD CITY –- Residents in three localities in Negros Occidental affected by the ashfall from Mount Kanlaon's eruption last June 18 have been advised to wear protective masks.

The ashfall was monitored to have covered areas in Barangays Ara-al, San Miguel and Yubo in La Carlota City, Barangay Sag-ang in La Castellana, and Barangay Ilijan in Bago City.

In Barangay Ara-al, a light sulfuric odor has also been detected.

Jay Jamello, science research specialist of Philippine Institute of Volcanology and Seismology (Phivolcs) in Negros Occidental, told residents of the affected areas, particularly children and elderly, to wear masks or cover their nose and mouth with a wet towel.

The sulphur from the ashfall could trigger asthma and pulmonary problems, he noted.

During Mt. Kanlaon’s eruption last March 29, ashfall was also reported in Salvador Benedicto in the First District; Bago City, La Carlota City and Pontevedra in the Fourth District; and La Castellana in the Fifth District.

Open water sources in these localities also had traces of ashfall from the earlier eruption, which produced a 1.5-kilometer high ash column.

Mt. Kanlaon has remained under Alert Level 1 status, or it is still at an abnormal condition and in the period of current unrest. It has been on unsettling status since November 23 last year.

The public is prohibited from entering the four-kilometer radius Permanent Danger Zone due to further possibilities of sudden and hazardous steam-driven or minor ash eruptions, Phivolcs said.

In Manila, Philvolcs said rocks and volcanic debris deposited over time along Mt. Kanlaon's slopes also pose danger to communities there aside from steam and ash eruptions.

Much rainfall during severe thunderstorms can dislodge materials along Kanlaon's slopes and send these cascading, warned volcanologist Paul Alanis from State-run Philippine Institute of Volcanology and Seismology (Phivolcs).

"People must guard against that possibility," he said.

He urged people to refrain from entering Mt. Kanlaon's four-kilometer radius permanent danger zone to lessen their risk for avalanches and exposure to falling volcanic materials.

Alanis recalls no rain-induced avalanche of rocks and volcanic debris in Mt. Kanlaon so far.

Such avalanche already happened in Mt. Mayon around 2001 and 2006 as well as in other volcanoes, he noted.

"There's possibility for similar occurrence in Mt. Kanlaon," he said.

Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) isn't discounting the likelihood of thunderstorms' occurrence in the Mt. Kanlaon area.

"Thunderstorms can occur there particularly during this time of the year," said Pagasa weather forecaster Obet Badrina.

He noted rainfall during thunderstorms can range from light to heavy.

"In some instances, however, such rainfall can even be intense," he also said.

Alanis and Badrina reminded people to monitor government's latest information on weather and volcanoes.

People must also heed government's safety warnings, they continued.

"No precipitation in lowlands doesn't mean an avalanche won't occur since it might be raining hard near a mountain's top, eventually dislodging materials there," noted Alanis.

According to Phivolcs, the first eruption of Mt. Kanlaon this weekend sent a light gray to white steam and ash plume rising some 1,500 meters into the air before further lofting about three kilometers above the summit there.

"This was followed immediately by eruption of dense dark gray to black ash plume 500 meters high," noted Phivolcs.

Phivolcs said emission of a 500 meter-high dark gray ash plume characterized the third eruption.

Light ashfall reached some parts of Negros Occidental province's La Carlota City, Bago City and La Castellana, Phivolcs continued.

Alanis noted the eruptions didn't deposit a significant volume of volcanic debris along Mt. Kanlaon's slopes.

The deposits will build up over time as eruptions occur so people must remain alert and vigilant, he said.

Alert level 1 continues prevailing in Mt. Kanlaon since Phivolcs said this volcano is still in a state of unrest.

In its bulletin released Monday, Phivolcs expects minor eruptions to likely persist there.

Hydrothermal processes in Mt. Kanlaon can generate such eruptions, it said.

Phivolcs also reported observing weak to moderate emission of a white steam plume rising up to some 600 meters there.

Such discharge drifted northwest and west-northwest, it added. (PNA)