The Philippine Institute of Volcanology and Seismology (Phivolcs) has detected 48 volcanic earthquakes and 40 tremor episodes in Taal Volcano in the past 24 hours.
Volcanic tremors, or long-lasting rhythmic shaking, recorded in Taal Volcano had durations ranging between 60 seconds and 90 seconds.
In its volcano bulletin issued on Tuesday (March 2), Phivolcs also observed weak emission of steam-laden plumes from the volcano's fumarolic vents during its 24-hour observation period.
Temperature highs of 74.6 degrees Celsius and pH of 1.59 were last measured from the main crater lake, respectively, on Feb. 18 and Feb. 12, 2021, Phivolcs added.
"Ground deformation parameters from continuous electronic tilt on volcano island record a slight deflation around the main crater since October 2020, but overall, very slow and steady inflation of the Taal region has been recorded by continuous GPS data after the eruption," it noted.
With these observations, Phivolcs said Taal Volcano remains under Alert Level 1 due to possible sudden steam-driven or phreatic explosions, volcanic earthquakes, minor ashfall, and lethal accumulations or expulsions of volcanic gas that can occur and threaten areas within the Taal Volcano island.
Phivolcs strongly discourages entry into the Taal volcano island, which is a permanent danger zone, especially the vicinities of the main crater and the Daang Kastila fissure.
The local government units were also advised to continuously assess previously evacuated barangays around Taal Lake for damages and road accessibilities and to strengthen preparedness, contingency, and communication measures in case of renewed unrest.
The public was also asked to continue to observe precautions due to ground displacement across fissures, possible ashfall, and minor earthquakes.
In the past 24 hours, Phivolcs has also detected seven volcanic earthquakes in Mt. Kanlaon.
From 8:00 a.m., March 1 (Monday) to 8:00 a.m., March 2 (Tuesday), Phivolcs observed "very weak to moderate emission of white steam-laden plumes that rose 300 meters before drifting northwest and southwest."
Phivolcs said sulfur dioxide emission was measured at an average of 892 tonnes per day on Feb. 27, 2021.
Ground deformation data from continuous GPS (global positioning system) and electronic tilt measurements have been recording a slight inflation of the lower and middle slopes since June 2020, it added.
"These parameters may indicate hydrothermal, tectonic, or deep-seated magmatic processes occurring deep beneath the edifice," Phivolcs said.
The local government units and the public were reminded to refrain from entering the four-kilometer permanent danger zone due to a continuing possibility of sudden and hazardous steam-driven or phreatic eruption.
Phivolcs also recommended civil aviation authorities to advise pilots to avoid flying close to Mt. Kanlaon and Taal Volcano as airborne ash and ballistic fragments from sudden explosions and wind-remobilized ash may pose hazards to aircraft.