The probability of eruption of Mount Mayon in Albay is getting slimmer every day as it continues to quiet down, prompting the Philippine Institute of Volcanology and Seismology to lower the alert status around the volcano to Level 2 last Wednesday.

Phivolcs noted that “a further decline in the overall activities of the volcano” observed since Jan. 2 prompted the downgrade from Alert Level 3 or “relatively high unrest” to Alert Level 2 or “moderate unrest.”

“This means a further reduction in the likelihood of hazardous eruption,” the agency said.

In a bulletin, Phivolcs Director Renato Solidum explained that there has been a declining trend in seismic activities of the perfect cone-shaped volcano in the last two weeks, with only six volcanic earthquakes recorded on Tuesday.

In spite of the improvements, Solidum said the lowering of the alert status should not be interpreted that volcanic unrest has ceased.

“If there is resurgence in the volcano’s activity, the alert level may be raised back to 3 but if there is noticeable downward trend in the monitored parameters, then the alert will be lowered to Alert Level 1,” he elaborated.

Solidum said majority of the recorded earthquakes since the start of the new year were related to rockfalls and lava fragments rolling down from the volcano’s upper slopes.

“The (Phivolcs seismic) network continues to record a few low frequency-type volcanic earthquakes associated with degassing of residual magma… The lack of remarkable seismic events, such as harmonic tremors, suggests no active transport of magma to shallow levels,” Solidum said.

He also explained that prior to and during Mayon’s eruption last December, there has been a decrease in water discharge of springs on the lower slopes as a result of the inflation of the volcano.

But since December 30 last year, Solidum said they monitored that springs have recovered and increased in discharge, and that results of precise leveling surveys conducted on Mayon’s northwest and southeast slopes from January 5 to 10 showed “deflationary trend.”

“These measurements indicate a return of the volcanic edifice to a deflated state, suggesting that no pressure build-up has taken place and reflect a general static condition of residual magma in the volcanic pipe and beneath the crater,” he explained.

Sulfur dioxide emission has likewise decreased considerably from a high 2,621 tons per day to a low average of 597 tons per day, indicating that there is no active magma intrusion beneath the volcanic edifice.

“No ash ejections were observed since Dec. 29 (while) steam emission was most of the time weak to moderate and white in color indicating considerable decrease in energy,” Phivolcs said.

“Crater glow remained visible to the naked eye at night possibly due to the still-hot residual magma beneath the crater,” the Quezon City-based institute added.