The Philippine Institute of Volcanology and Seismology (Phivolcs) continued to observe "increased unrest" at Taal Volcano in the past 24 hours.
In a volcano bulletin issued on Tuesday, June 22, Phivolcs detected 24 volcanic tremor events having durations of one to 10 minutes and low-level background tremor that has persisted since April 8, 2021.
The activity at the main crater was dominated by the upwelling of hot volcanic fluids in its lake which generated plumes 1.2 kilometers tall.
Phivolcs said Taal Volcano's sulfur dioxide emission remains high with an average of 5,604 tonnes daily on Monday, June 21.
The highest sulfur dioxide flux recorded for Taal Volcano averaged 9,911 tonnes on June 10.
"Based on ground deformation parameters from electronic tilt, continuous GPS and InSAR monitoring, Taal Volcano Island has begun deflating in April 2021 while the Taal region continues to undergo very slow extension since 2020," it said.
Phivolcs pointed out that these parameters indicate overall that magmatic unrest continues to occur at shallow depths beneath the edifice, thus Alert Level 2 is maintained.
Taal Volcano has been under Alert Level 2 since March 9, 2021.
Phivolcs reiterated that there remains a possibility of sudden steam- or gas-driven explosions, volcanic earthquakes, minor ashfall, and lethal accumulations or expulsions of volcanic gas that can occur and threaten areas within and around the Taal Volcano Island.
It said that entry into the volcano island, which is a permanent danger zone, especially the vicinities of the main crater and Daang Kastila fissure, should be strictly prohibited.