There's a slim chance that Mayon Volcano will exhibit an explosive eruption despite being categorized in "relatively high unrest" status, the chief of the Philippine Institute of Volcanology and Seismology said Friday.

"The parameters we are observing now are not too elevated, compared to the parameters observed in July and August," Phivolcs Director Teresito Bacolcol said in an interview over the Bagong Pilipinas Ngayon public briefing.

However, Bacolcol said Mayon still exhibiting an effusive eruption, with the lava flows have maintained their advances to approximately 3.4 kilometers in Bonga (southeastern), 2.8 kilometers in Mi-isi (south), and 1.1 kilometers in Basud (eastern) gullies.

The Phivolcs expect this Mayon's effusive eruption to continue for several weeks or more, he added.

Alert Level 3 has been maintained in the Albay province's Mayon since June, which means that a relatively high level of unrest and hazardous eruption within weeks or even days are possible.

Bacolcol said they are monitoring two factors to consider before lowering the volcano to Alert Level 2; when the flow of lava and occurrence of pyroclastic density current would stop.

As of Friday, Phivolcs logged 18 volcanic earthquakes, 95 rockfall events, and 3 PDC events.

Meanwhile, Bacolcol said volcanic smog or vog is also unlikely in Mayon, because of the low volume of sulfur dioxide emission.

Mayon emitted an average of 761 tonnes of volcanic SO2 per day on 28 September.

"This is not as huge compared to the S02 emission in Taal in the Batangas province. Mayon's S02 emission could be dispersed easily," he said.

He added that continuous rainfall may result in lahars and sediment-laden streamflows in channels where PDC deposits were emplaced.

Entering the Mayon's 6-km radius Permanent Danger Zone remains prohibited due to the danger of PDCs, lava flows, rockfalls, and other volcanic hazards.