Phivolcs: Taal weakening, but more info needed before lowering alert level

Kristine Sabillo, ABS-CBN News

Posted at Jan 16 2020 08:51 PM

A fisherman attempts to catch fish a day after the Taal volcano erupted in Talisay, Batangas on January 13, 2020. George Calvelo, ABS-CBN News

With the smaller eruptions on Taal Volcano slightly waning, the Philippine Institute of Volcanology and Seismology (Phivolcs) on Thursday said it’ll have to check if lowering the alert level on the volcano is possible.

“Ang kaniyang pagsabog ay maituturing na mahina o weak,” Phivolcs director Renato Solidum said of the phreatic eruptions and ash plumes seen on the volcano island. 

In its 5 p.m. update on Thursday, the Phivolcs said it only monitored “weak emission of steam-laden plumes” that were 800 meters high, slightly lower than previous days. There were also 9 “discrete weak explosions” recorded by their instruments.

However, Solidum said the institute is still monitoring the volcanic earthquakes that continue to plague the area. 

There have been 595 volcanic earthquakes since January 12, 1 p.m. Of that number, 176 were felt with Intensities I to V, stronger than usual volcanic quakes

Despite no additional fissures reported, Solidum said the earthquakes are proof there is still movement of magma underground.

But in case the situation no longer escalates, Solidum said the alert level can be lowered.

“Our stand-down procedure is two weeks but, of course, we can adjust,” he said. “What is important is that if we decide to stand down (lower the alert level), there is a definite trend of weakening).”

Phivolcs volcano monitoring and eruption prediction division chief Mariton Bornas clarified that the current situation is only a “relative lull.”

“There are still activities in the volcano. There is still steaming,” she said. “What is happening underneath continues.”

Bornas said her division will know for sure once the data from the newly revived Taal Volcano Network is process.

For the past days, the Phivolcs could not retrieve data from its stations around Taal that were covered in ash. Now that most have been revived, officials have started receiving more data.

“We need to consolidate the data since we did not receive transmission from our Taal Volcano Network for many days. We’ll see the total seismicity once we process them,” she said.

Bornas said the only time the alert level is lowered is when no magma movement can be seen.

However, they will also have to take into account if there is already magma that has risen toward the main crater.

“Can this erupt?” Bornas said. “We also need to monitor if the sulfur dioxide emissions are increasing. This would mean that the magma is close to the surface.”

On Thursday morning, sulfur dioxide emission was at 4,186 tonnes per day, higher than the day before. However, it is also lower than when Taal started its phreatic eruptions on Sunday.

For now, Solidum said: “We’ll maintain Alert Level 4 for Taal Volcano. A hazardous explosive eruption is still possible.”

The Phivolcs has identified high-risk areas within the 14-kilometer radius of the main crater. They said people should stay away from these areas until local government units allow them to return to their houses.