Increase in seismic activity seen in Taal Volcano

MANILA – The Philippine Institute of Volcanology and Seismology (Phivolcs) on Wednesday said increase in seismic activity has been observed in Taal Volcano.

In an advisory, Phivolcs said 2,015 volcanic tremors, 734 low-frequency volcanic quakes and 18 hybrid earthquakes were recorded in Taal since February 13.

Volcanic quakes are caused by movements or eruptions of magma from the volcano. Hybrid earthquakes, on the other hand, indicate rock fracturing and magma or fluid movement.

Harmonic tremor associated with magma migration has become the dominant type of earthquake since March 19, according to Phivolcs.

Most earthquake events occurred at shallow depths of less than two kilometers; some large earthquakes were generated in the deeper two to six-kilometer region beneath the Taal Volcano Island (TVI) edifice.

“Overall seismic energy release has markedly increased since yesterday afternoon compared to previous seismic swarms,” the advisory read.

About 259 volcanic earthquakes were generated in Taal for the past 24 hours.

Other parameters showed sulfur dioxide gas emission in the previous week has been generally high, with a peak of 1,184 tonnes/day last March 21.

These indicate that magma has been migrating across shallow depths beneath TVI, increasing the possibilities of magmatic eruption.

Taal Volcano has been on alert level 2 (increasing unrest) since March 9. The unrest has been elevating and is under constant evaluation, Phivolcs said.

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.

Entry into TVI, Taal’s permanent danger zone (PDZ), is strictly prohibited.

Phivolcs has advised local government units to continuously assess and strengthen the preparedness of previously evacuated barangays around Taal Lake in case of renewed unrest.