Mayon Volcano continued to remain under Alert Level Three even as its activity dropped in the past 24 hours.

As of Tuesday morning, the Mayon Volcano Network recorded one volcanic earthquake and 221 rockfall events based on seismic and visual observations.

In a radio interview, Philippine Institute of Volcanology and Seismology (Phivolcs) Director Teresito Bacolcol said despite the decrease of recorded volcanic activity the agency continued to monitor the development in Mayon volcano.

"In the past 24 hours we only recorded a low frequency volcanic earthquake in contrast to the 21 weak volcanic earthquake we recorded between June 11 and 12, so when we look at the parameters its decreasing again but we have to look at this in the next few days because like the sulfur dioxide readings that fluctuates," he said.

"Yesterday we only recorded a low primitive volcanic earthquake... this time only one was recorded and the sulfur dioxide slightly went up but not as much as the 1,205 tons per day which we recorded two days ago, yesterday 723 tons per day," he added.

Phivolcs said "very slow effusion of lava from the summit crater emplaced lava flow and collapsed debris on the Mi-isi (south) and Bonga (southeastern) gullies within approximately a kilometer from the crater" was monitored while "one dome-collapse pyroclastic density current (PDC) that lasted two minutes was also detected via seismic signals and was visually observed."

"Thin ash from the rockfalls and continuous moderate degassing from the summit crater produced steam-laden plumes that bent and crept downslope before drifting northeast. Fair crater glow or “banaag” and incandescent rockfall shed from new fluidal lava at the summit of Mayon Volcano was observed," it said. Robina Asido/DMS