MANILA – Despite a minor phreatomagmatic eruption and increased seismic energy observed in the Taal Volcano on Monday, the volcano’s parameters remained under Alert Level 1, the head of the Philippine Institute of Volcanology and Seismology (Phivolcs) said Tuesday.
“The increase in real-time seismic amplitude measurement (RSAM) which we noticed in Taal Volcano lately indicates a possible blockage in the volcano’s gas pathways,” Phivolcs Director Teresito Bacolcol told the Philippine News Agency in an interview.
Such blockage causes pressure buildup inside, leading to heightened seismic energy release as the volcano attempts to release trapped gases, he explained.
This could result in phreatomagmatic eruption, which was observed from 7:34 p.m. to 7:37 p.m. Monday.
The activity, which also generated a 600-meter plume, is consistent with Alert Level 1 or low-level unrest, according to Bacolcol.
There could be several causes of the blockage.
When magma cools and hardens into rock, or when magma is sticky, this could clog the vent.
Blockage could also happen when rocks, debris or minerals build up and block the conduits inside the volcano, Bacolcol added.
In an advisory on Monday afternoon, Phivolcs said visual observations noted the absence of a degassing plume from the Taal main crater since the start of RSAM increase.
Taal has been degassing sustained levels of sulfur dioxide for the past four years with the latest emission measured on December 30, 2024 averaging 2,753 tonnes.
“The sharp increase in RSAM and the lack of observable degassing from the Main Crater may indicate blockage or plugging of volcanic gas pathways within the volcano, which may lead to short-term pressurization and trigger a phreatic or even a minor phreatomagmatic eruption,” the advisory read.
The advisory also indicated that only 12 volcanic earthquakes including six tremor events were recorded in Taal since January 1, 2025.
Bacolcol said that while the activity is within Alert Level 1, it is important for residents and the public to avoid entering the permanent panger zone which covers the entire Taal Volcano Island.
There is possibility that a phreatic or phreatomagmatic would occur without warning, Bacolcol said. (PNA)