(PNA file photo

MANILA – Due to the decline in volcanic activity, the Philippine Institute of Volcanology and Seismology (Phivolcs) on Saturday lowered Taal Volcano's alert status from Level 3 (magmatic unrest) to Level 2 (decreased unrest).

In an advisory, Phivolcs said 86 small-magnitude and imperceptible volcanic earthquakes have been recorded since the volcano's eruption last March 26.

Most of the recorded earthquakes were generated by volcanic degassing from the shallow magma and hydrothermal region beneath the Taal Volcano Island (TVI) edifice.

Volcanic earthquakes are caused by movement or eruptions of magma from the volcano, compared to tectonic quakes which are caused by fault movements. Phreatomagmatic eruption, on the other hand, is caused by the interaction of magma and water.

"There has been no recorded seismic activity related to new magmatic intrusions from Taal’s deeper magma source since unrest began last year," the advisory read.

Meanwhile, Taal Volcano's sulfur dioxide (S02) emission elevated in the first three weeks of March, has reached 21,211 tonnes on March 16. The S02 emission declined on April 3.

Since then, the S02 emission had an average of 240 tonnes per day and further decreased to 103 tonnes on April 8, the lowest flux recorded since unrest began last year.

Phivolcs said the recent gas emissions indicate that the potential for eruptive activity is currently low.

"Activity in the main crater in the past week has been characterized by occasional weak plumes and longer periods of absence thereof, consistent with the significant decrease in magmatic degassing," Phivolcs added.

Phivolcs, however, noted that lowering the Taal Volcano's alert level does not mean unrest has ceased or the threat of an eruption is unlikely.

Those residing in high-risk areas who have returned are advised to be prepared for a quick and organized evacuation.

At Alert Level 2, sudden steam-driven or phreatic explosions, volcanic earthquakes, ashfall, and lethal accumulations or bursts of volcanic gas can occur and threaten areas within Taal and along its coast.

Entry into TVI is still prohibited. Phivolcs also advised local government units to continually strengthen preparedness, contingency, and communication measures, especially for previously evacuated high-risk barangays in case of renewed unrest. (PNA)