The Philippine Institute of Volcanology and Seismology (Phivolcs) said it had recorded "zero volcanic earthquake and low-level background tremor" within the past 24-hour monitoring of the restive volcano in Batangas, from Sunday to Monday, April 4 to 5.
Taal Volcano had a total of 40 earthquakes, consisting of 11 episodes of volcanic tremor and 29 low-frequency quakes during its previous monitoring from Saturday to Sunday, April 3 to 4.
In the latest volcano bulletin issued on Monday, Phivolcs observed a "weak" emission of steam-laden plumes from Taal Volcano's vents that rose 50 meters high.
Taal Volcano's sulfur dioxide emission was measured at 1,541 tonnes per day on Sunday from 1,216 tonnes per day on Saturday.
Phivolcs said 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.
It 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.
Phivolcs pointed out that Taal Volcano remains under Alert Level 2 "but that unrest has been elevating and is under constant evaluation."
Its alert level has been raised from 1 to 2 on 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 warned.
It advised the public to prevent 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 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.