Taal Volcano remained under abnormal condition as it continues to manifest "increased unrest" in the past 24 hours.
In a volcano bulletin issued on Saturday, May 15, the Philippine Institute of Volcanology and Seismology (Phivolcs) said Taal Volcano logged 20 earthquakes, including 14 low-frequency quakes and three volcanic tremor events having durations of three minutes, and low-level background tremor that persisted since April 8.
Likewise, Phivolcs noted that activity at the Taal's main crater was dominated by the upwelling of hot volcanic fluids in its lake which generated 200-meter tall but weak plumes that drifted to the southwest.
Taal Volcano's sulfur dioxide emission also remains high at 2,578 tonnes per day as recorded on Thursday, May 14.
Meanwhile, temperature highs of 71.8 degrees Celsius and pH of 1.59 were last measured from the main crater lake on March 4 and Feb. 12, 2021, respectively.
Phivolcs added that ground deformation parameters continued to indicate 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," 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 (Taal Volcano Island)," 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 added.
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.