The Philippine Institute of Volcanology and Seismology (Phivolcs) on Tuesday, Feb. 16, allayed fears of a possible connection between the recent volcanic activities of Mt. Kanlaon in Negros Island and Taal Volcano in Batangas, saying it is just a coincidence that they are showing abnormalities at the same time.

Department of Science and Technology Undersecretary and Phivolcs Director Renato Solidum noted that both volcanoes have been on Alert Level 1 status since last year, which means they are both under "abnormal" status and thus exhibiting volcanic unrest.

"There is no connection. Both volcanoes are two of the most active volcanoes, and sometimes, they show abnormalities at the same period," Solidum said.

"The alert levels are prescribed based on monitored parameters and we are closely monitoring these volcanoes," he added.

While Phivolcs has monitored a slight increase in activity in both Mt. Kanlaon and Taal Volcano, Solidum sees no need yet to raise the alert levels in both volcanoes. 

"Not yet but it is important (to note) that threat of phreatic eruption or steam driven explosion has increased and people should not enter the permanent danger zone--the whole of Taal Volcano Island and four-kilometers radius from summit of Kanlaon," he said.

Based on Phivolcs' volcano bulletin issued on Tuesday, Taal Volcano had 98 tremor episodes that lasted five to 12 minutes in the past 24 hours.

Taal Volcano's main crater also showed "weak emission of white steam-laden plumes from fumaroles that rose 5 meters high."

"Temperature highs of 77.1 degrees Celsius (°C) and pH of 1.59 were last measured from the main crater lake on Feb. 12, 2021.

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 (global positioning system) data after the eruption," Phivolcs said.

It reminded the public that Taal Volcano is still under Alert Level 1 as there remains an increased possibility of sudden steam-driven or phreatic explosions, lethal accumulations or expulsions of volcanic gas and minor ashfall from the main crater that can occur and threaten areas within the volcano island. 

Entry into the Taal Volcano Island, which is a permanent danger zone, especially the vicinities of the main crater and Daang Kastila fissure, is strictly prohibited. 

Phivolcs advised local government units 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.

People were also asked to observe precautions due to possible ashfall, ground displacement across fissures and minor earthquakes in the event of a phreatic eruption. 

Meanwhile, Phivolcs monitoring network recorded 33 volcanic earthquakes during its 24-hour observation of Mt. Kanlaon.

Moderate emission of white steam-laden plumes 700 meters high was observed. 

Sulfur dioxide emission was also measured at an average of 1,130 tonnes/day on Feb. 13, 2021, while ground deformation data from continuous GPS and electronic tilt measurements have been recording a slight inflation of the lower and middle slopes since June 2020, Phivolcs said.

"These parameters may indicate hydrothermal, tectonic, or deep-seated magmatic processes occurring deep beneath the edifice," it pointed out.

Phivolcs said Mt. Kanlaon remains under Alert Level 1, which means the active volcano is in an "abnormal condition" but still at a "low level of volcanic unrest."

It appealed to the public to be vigilant and refrain from entering the four-kilometer permanent danger zone "due to further possibilities of sudden and hazardous steam-driven or phreatic eruptions."

Civil aviation authorities were asked to advise pilots to avoid flying close to the summit of Taal and Kanlaon volcanoes as ejecta from any sudden phreatic eruption can be hazardous to aircraft.