By Elllalyn De Vera-Ruiz
The Philippine Institute of Volcanology and Seismology (Phivolcs) continues to observe weaker steam emission at the main crater of the Taal Volcano on Thursday, days after the alert status of the restive volcano was lowered.
Phivolcs pointed out that the activity in the volcano’s main crater from 8 a.m. Wednesday to 8 a.m. Thursday was characterized by “weak emission of white to dirty white steam-laden plumes 300 to 500 meters tall that drifted southwest.”
The sulfur dioxide emission was also below instrumental detection. The presence of significant sulfur dioxide from a volcano indicates that magma is getting closer to the surface.
Phivolcs added that seven volcanic earthquakes were plotted with magnitudes ranging from 1.7 to 2.5. However, these were not felt.
For the past 24 hours, the Taal Volcano network, which can record small earthquakes undetectable by the Philippine seismic network, recorded 137 volcanic earthquakes including two low-frequency events and one harmonic tremor that lasted for 97 seconds.
“These earthquakes signify magmatic activity beneath the Taal edifice that could lead to eruptive activity at the main crater,” Phivolcs said.
Alert Level 3 remains in effect over Taal Volcano, which means that sudden steam-driven and even weak phreatomagmatic explosions, volcanic earthquakes, ashfall, and lethal volcanic gas expulsions can still occur and threaten areas within the Taal Volcano Island and nearby lakeshores.
Phivolcs recommended that entry into the Taal Volcano island, Taal Lake, and communities west of the volcano island within a 7 kilometer radius from the main crater must be strictly prohibited.
Local government units were advised to assess areas outside the seven-kilometer radius for damages and road accessibilities and to strengthen preparedness, contingency, and communication measures in case of renewed unrest.
People were also advised to observe precautions due to ground displacement across fissures, frequent ash fall, and minor earthquakes.
Communities beside active river channels, particularly where ash from the main eruption phase has been thickly deposited, should increase vigilance when there is heavy and prolonged rainfall since the ash can be washed away and form lahars along the channels.
Likewise, civil aviation authorities were asked to advise pilots to avoid flying close to the volcano as airborne ash and ballistic fragments from sudden explosions and wind-remobilized ash may pose hazards to aircrafts.