Residents around Kanlaon Volcano are advised to be vigilant due to increased seismicity and long-duration tremors observed over the past 24 hours, the head of the Philippine Institute of Volcanology and Seismology (Phivolcs) said on Monday, April 13.

At least 150 volcanic earthquakes, including four volcanic tremors with 40 to 100 minutes duration, were recorded.

“This may be considered an increase in seismicity at Kanlaon. The number of earthquakes, including several long-duration tremors, show that the volcano remains active internally,” Phivolcs Director Teresito Bacolcol told the Philippine News Agency in an interview.

These show that the volcano “is not quiet,” and the residents around Kanlaon Volcano should remain vigilant, Bacolcol said.

“Kanlaon Volcano shows continued internal activity,” he added.

Alert Level 2 or increased unrest is maintained over Kanlaon Volcano.

Bacolcol, however, clarified that not all tremors lasting more than an hour are automatically unusual.

Some volcanic tremors can last several hours, he said, and in some volcanoes like Taal, they may persist for several days or much longer.

A volcanic tremor in Taal went on for 221 days, between July 2021 to February 2022.

Last year, there were several tremors in Taal Volcano that lasted for a few days, Bacolcol said.

For areas near Kanlaon, Bacolcol reiterated that the four-kilometer radius permanent danger zone (PDZ) should remain a no-entry zone even at Alert Level 0 because sudden hazardous events, like phreatic eruptions, could happen without warning.

He said Phivolcs recognizes that there are residents inside the PDZ and some could not leave because their livelihoods are also within the PDZ.

“However, we always maintain that the PDZ is not meant for permanent settlement because it is inherently hazardous,” he added. (PNA)