MANILA -- Thicker steam-laden plumes were observed at Taal Volcano early Friday morning, but the Philippine Institute of Volcanology and Seismology (Phivolcs) said it should not be a cause of worry for now.
Phivolcs Volcano Monitoring and Eruption Prediction Division head Mariton Bornas said the emission of steam meant that magma was rising underground and that it was heating up the ground water, which resulted in steam.
“We noticed that the steam slightly subsided in recent days. It’s possible that the vents were just blocked,” she said, explaining that the amount of steam depends on the changing water under the volcano. “Now that the steam is more intense, the blockage might have been removed.”
She said the change in the color of the plumes, from white to a darker color, was just the mixing of old ash from the volcano in the steam. As of 10 a.m., white-colored plumes were again being emitted by the volcano.
Asked if the steam meant the volcano was about to erupt, Bornas said she could not say that. “It’s not that simple. We have to look at other parameters.”
During past briefings, Bornas and Phivolcs director Renato Solidum said that the better gauge would be the tilting of the ground on volcano island and the energy of the volcanic earthquakes.
Based on Phivolcs’s Friday morning bulletin, from Thursday morning to Friday morning, the Taal Volcano Network detected 486 volcanic earthquakes in the area. Of this number, 4 were low-frequency earthquakes, which are linked to magma movement.
“Such intense activity may lead to further eruptive activity,” the bulletin said.
Meanwhile, the sulfur dioxide level was just an average of 224 tons per day, much lower than the more than 5,000 tons per day measured on Jan. 12 when the phreatic or steam-driven eruptions started at Taal Volcano.
However, sulfur dioxide levels can also fluctuate because of blockages in the vents of the volcano. Sulfur dioxide is used to measure if magma is getting closer to the surface.
In the last couple of days, Taal Volcano showed weaker emissions and lower plumes.
Phivolcs said that if the trend continues for 2 weeks, they can consider lowering the alert level of Taal Volcano from 4 to 3. Alert level 4 means a hazardous explosive eruptions is expected within hours or days.
Asked if the stronger steam would reset their 2-week count, Bornas said they’ll have to get more data, especially on the sulfur dioxide, ground deformation and earthquake readings.
While the probability had gone lower, Bornas said there was still a “significant probability that we will have a 1754 or 1911 scenario.”
The 1754 and 1911 eruptions are considered the most violent and devastating for Taal Volcano. Both eruptions resulted in volcanic tsunamis and base surges or blasts of hot gas, ash and debris, which killed people on the volcano island and the lakeshore communities.
With Alert Level 4 still up for Taal Volcano, people from the island and the high-risk areas within the 14-kilometer radius of the main crater have been evacuated.
Bornas said any ash that might be generated by the low plumes would most likely fall in the Batangas towns of Agoncillo, Lemery and Laurel, and also Taal and San Nicolas.