MANILA, Philippines – State volcanologists recorded fewer volcanic earthquakes at Taal Volcano in the past 24 hours, continuing a fluctuating trend.

The Philippine Institute of Volcanology and Seismology (Phivolcs) said on Thursday, February 13, that the Taal Volcano Network recorded 71 volcanic earthquakes in the past 24 hours. This is lower than the 101 in the previous 24-hour period.

The number of quakes have been rising and dropping in the past few days.

There were no low-frequency events or harmonic tremors among the volcanic earthquakes in the past 24 hours. Low-frequency events are “caused by cracks resonating as magma and gases move toward the surface,” while harmonic tremors involve prolonged shaking.

Nonetheless, Phivolcs reiterated that volcanic earthquakes indicate the movement of magma underneath Taal’s crater. This magma may either remain below or rise to the surface.

Meanwhile, the sulfur dioxide (SO2) emission again went down, measured at an average of 59 tons per day on Wednesday, February 12. It was at 67 tons per day on Tuesday, February 11, and 105 tons on Monday, February 10.

SO2 is a major gas component of magma and one of the parameters used by Phivolcs to assess volcanic activity.

At Taal’s main crater, there was also “weak emission of steam-laden plumes rising 50 to 100 meters high” for the 3rd straight day.

Phivolcs said it is maintaining Alert Level 3 for Taal given the current conditions. These may happen any moment:

• sudden steam-driven and even weak phreatomagmatic explosions, which result from the interaction of water and magma
• volcanic earthquakes
• ashfall
• lethal volcanic gas expulsions

Alert Level 3 has been in effect since January 26, a downgrade from Alert Level 4 which was raised on January 12, the day the unrest began.

Filipinos have been waiting for the volcano to be downgraded further to Alert Level 2. Phivolcs generally follows a two-week observation period where all parameters must consistently go down.

The highest category is Alert Level 5, which would be raised if a hazardous eruption is already in progress.

At the moment, it is still dangerous to be within a 7-kilometer radius of Taal’s main crater. The following areas in Batangas remain on lockdown:

• Taal Volcano Island
• barangays of Bilibinwang, Subic Ilaya, and Banyaga in Agoncillo
• barangays of Gulod, Buso-Buso, and Bugaan East in Laurel

There are still 4,263 families or 15,295 persons staying in evacuation centers as of Thursday, from a high of over 38,000 families.

The Taal unrest has affected at least 151,008 families or 565,005 persons in Batangas, Quezon, Laguna, and Cavite. – Rappler.com