The Philippine Institute of Volcanology and Seismology (Phivolcs) on Tuesday, May 18, said the elevated unrest in Taal Volcano in Batangas has been recurring and that its condition remains unstable.
In the past 24 hours, Phivolcs said Taal Volcano had 288 earthquakes, including 39 low-frequency quakes and 249 tremor events having a duration of one to 20 minutes, and low-level background tremor that has persisted since April 8, 2021.
Most of the volcanic earthquakes were “very shallow” and generated within five kilometers beneath the Taal Volcano Island (TVI) and northeast of Taal Lake.
Phivolcs also monitored the upwelling of hot volcanic fluids in the main crater lake and active degassing from fumaroles or vents on the main crater that produced 300-meter-high steam-laden plumes since daybreak Tuesday.
Taal Volcano’s sulfur dioxide emission averaged 2,214 tonnes per day as reported on Monday, May 17.
Phivolcs noted slight but very abrupt inflation of Taal Volcano Island that began on Monday, based on the electronic tilt monitoring of the volcano.
Meanwhile, longer-term ground deformation parameters continue to record a “very slow and steady inflation and expansion of the Taal region that began after the January 2020 eruption.”
“These parameters indicate persistent magmatic activity at shallow depths beneath the edifice,” it said.
“Alert Level 2 (increased unrest) is currently maintained over Taal Volcano, but elevated unrest has been recurring and volcano conditions remain unstable,” Phivolcs pointed out.
The restive volcano in Batangas has been under Alert Level 2 since March 9, 2021.
“Sudden steam-driven or phreatic explosions, volcanic earthquakes, minor ashfall, and lethal accumulations or expulsions of volcanic gas can occur and threaten areas within and around TVI,” Phivolcs pointed out.
It warned the public from entering the volcano island, which is a permanent danger zone, especially the vicinities of the main crater and Daang Kastila fissure.
Occupancy and boating on Taal Lake should also be strictly prohibited, Phivolcs said.
Local government units were advised to continuously assess and strengthen the preparedness of previously evacuated barangays around Taal Lake in case of renewed unrest.
Civil aviation authorities were also asked to advise pilots to avoid flying close to the volcano as airborne ash and ballistic fragments from explosions and wind-remobilized ash may pose hazards to aircraft.