The Philippine Institute of Volcanology and Seismology (Phivolcs) on Monday, March 29 recorded 19 volcanic quakes, which consist of 12 episodes of volcanic tremor lasting one to 11 minutes, and seven low frequency volcanic earthquakes in Taal Volcano in the past 24 hours.
Based on its volcano bulletin, Phivolcs also observed "weak" emission of steam-laden plumes rising 40 meters.
It measured sulfur dioxide emission at an average of 837 tonnes per day on March 28, while 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 after the January 2020 eruption."
"These parameters may indicate increased magmatic activity at shallow depths beneath the edifice," it said.
Taal Volcano will remain under Alert Level 2 due to continuous detection of "increased unrest," it pointed out. Its alert level has been raised from 1 to 2 on March 9.
"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)," it 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 be also 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 sudden explosions and wind-remobilized ash may pose hazards to aircraft.