The Philippine Institute of Volcanology and Seismology (Phivolcs) has monitored a continuous tremor-like series of weak volcanic earthquakes which caused "abrupt and sustained increase" in seismic energy release in Mayon Volcano.
In an advisory posted on Tuesday afternoon, Phivolcs said the weak volcanic earthquakes lasted for 11 seconds and it recurred every 5 seconds.
“This resulted in an abrupt and sustained increase in the level of seismic energy release beginning 03 July 2023,” it said.
Alongside is the increase in sulfur dioxide emission that averaged 1,558 tonnes on Tuesday alone.
“This current phase of unrest is likely driven by magmatic gas activity within the edifice,” Phivolcs noted.
The state seismologist said the dome-collapse pyroclastic density currents (PDCs) have flowed down the eastern Basud Gully and southern Mi-si Gully within a distance of 1 to 2 kilometers from the Mayon Volcano’s crater for about two minutes.
Phivolcs said trace ashfall from the PDCs was reportedly experienced by residents of Guinobatan Municipal and Ligao City.
“DOST-PHIVOLCS reiterates that Alert Level 3 (increased tendency towards a hazardous eruption) still currently prevails over Mayon Volcano, but that the increase in seismic energy release is being closely monitored,” it said.
The state seismologist strongly recommended that residents living within a six-kilometer permanent danger zone (PDZ) remain in evacuation centers while those within the seven and eight-kilometer radius be prepared to vacate their homes once the PDC activity worsens.
