LEGAZPI CITY -- The Philippine Institute of Volcanology and Seismology (Phivolcs) raised alert level 1 over Mayon volcano in Albay province on Monday, November 6, after it recorded 25 volcanic earthquakes and the sulfur dioxide (SO2) emission went significantly higher than the standard measurement.

In its latest bulletin, Phivolcs said the quakes that rocked the volcano and the spewing of an above normal SO2 gas signify that the volcano remains restive. SO2 emission was measured at 633 tonnes which is significantly higher than the standard measurement of 500 per day.

The volcanic quakes total to 91 for the past two days.

When asked about the increasing SO2 emission, Phivolcs volcanologist Ed Laguerta said the abnormal emission could either be due to steam degassing or magma pressure beneath the volcano vent.

"Aside from the quakes and the abnormal rate of SO2 emitted by the volcano, we are still validating other given parameters using other instruments," Laguerta said.

The parameters that are directly associated with eruptions include earthquakes, gas emission, dome growth, crater glow, lava flow, pyroclastic flows, and ash fall.

Cedric Daep, Albay Public Safety Emergency Management Office (Apsemo) executive director, said with the elevated abnormal behavior of Mount Mayon, disaster authorities would strictly enforce the “no human activity” protocol inside the six-kilometer (km) Permanent Danger Zone (PDZ).

Daep said visitors as well as villagers living close to the six-km PDZ are prohibited from climbing to the Mayon crater.

He said that while the Alert Level 1 (abnormal condition) is hoisted over the volcano, those residents living outside the 6-km PDZ could continue with their normal activities in towns and cities surrounding the volcano. (PNA)