MANILA, Philippines – The Philippine Institute of Volcanology and Seismology (Phivolcs) warned of a spike in low-frequency volcanic earthquakes (LFVQs) and sulfur dioxide (SO2) emissions from Mayon Volcano in Albay, observed in recent days.

Phivolcs said in an advisory on Tuesday, July 18, that there has been a continuous series of weak LFVQs totaling 573 since Sunday, July 16.

“Some of these LFVQs were detected by infrasound sensors and were reported to have produced audible rumbling sounds” on Monday evening, July 17, and Tuesday morning.

“Based on seismic analyses, most of the events originated from a shallow source and are associated with rapid releases of volcanic gases,” Phivolcs also said.

But the agency added that there are “no significant increases in overall seismic energy release,” so far.

Meanwhile, SO2 emissions have been on the rise since Wednesday, July 12, peaking at an average of 2,989 tons per day on Saturday, July 15.

Tuesday’s SO2 emission was 1,945 tons per day.

Phivolcs said the background level is usually just 500 tons per day when Mayon is relatively quiet.

The agency maintained Alert Level 3 for the volcano, but stressed that “seismic and degassing parameters have been undergoing changes that may progress into further activity.”

Alert Level 3, which means there is an “increased tendency towards a hazardous eruption,” has been in effect since June 8.

The raising of Mayon’s alert level prompted thousands of families to evacuate from the 6-kilometer-radius permanent danger zone around the volcano.

The Albay Provincial Information Office said in a Facebook post on Tuesday that 4,334 families have started to receive emergency cash assistance from the Department of Social Welfare and Development. Each family will be getting P12,330, according to the Albay PIO. – Rappler.com