Taal shows 'continuous steaming,' another phreatomagmatic eruption possible: Phivolcs

Gillan Ropero, ABS-CBN News

Posted at Jul 05 2021 10:59 AM

Taal shows 'continuous steaming,' another phreatomagmatic eruption possible: Phivolcs 1
Locals prepare their boats to bring feeds to their fish pens at the Taal Lake in Agoncillo, Batangas on July 3, 2021. George Calvelo, ABS-CBN News

MANILA - Taal Volcano shows continuous steaming a day after it recorded its "highest ever" sulfur dioxide emission at 22,628 tons, Phivolcs said Monday.

The steaming is due to an upwelling of volcanic gas on the main crater lake of Taal Volcano, said Phivolcs officer-in-charge Renato Solidum.

"This means there’s a possibility that a similar phreatomagmatic eruption last Thursday may occur in Taal Volcano area," he told ANC's Headstart.

"The explosion can trigger pyroclastic density current that can move horizontally and move across lake water."

Phivolcs could see a scenario where the eruption "might generate the base surge which can cross the waters and that can generate base surge on the mainland and volcanic tsunami," according to Solidum. A base surge is a deadly lateral blast of hot gas, ash, and volcanic debris. 

"It is also possible that when the lake water dries up, we can see if there will be continued eruption, there can be fountaining or fireworks of molten rocks and lava flow would ensue. That would be a better type of eruption because it will not be as dangerous," he said.

"Of course at some point, the other scenario would be the volcano would cease to erupt."

The volcano's recent eruption and explosion last year were both phreatomagmatic but the former was de-gassed, Solidum said. Phreatomagmatic eruption is a result of new magma and water interacting.

"Last year, if people would recall during the height of the explosion, there were many earthquakes felt all over Batangas, even days and weeks after," he said.

"This meant new magma has been resupplied from a sourceway below Balayan Bay diagonally moving up to the volcano. So there’s a resupply of new magma founded 4 to 5 kilometers below. That explains why there will still be some activities inside the volcano."

LONG-TERM PLAN

The local government and national agencies need to come up with a long-term development plan for the area to address the livelihood of displaced residents, Solidum said.

Solidum cited as an example where residents went back to the volcano island in the 1970s following the 1965 eruption of Taal, which left some 200 people dead.

"There must be a long-term development plan that must consider the hazard and the risk. Whatever investment, people communities that are settled in the danger areas must be considered fully evaluated so that if the volcano would frequently erupt form time to time, the economic development of an area will be less affected than presently what is happening," he said.

"Essentially, a development plan can be considered where livelihood can still exist very close to the volcano, not on the volcano island but those on the lake shore. Major economic activities can be placed further out. This would be for the moderate-size explosion."

Citing a report from the affected area, the National Disaster Risk Reduction and Management Council on Monday said 1,563 families or 5,583 individuals have evacuated in Batangas, most of whom are staying in 22 evacuation centers.

Batangas Governor Hermilando Mandanas on Sunday, though, reported a higher figure of 15,000 residents who fled their homes due to the eruptions.

The public can monitor volcanic activity and other hazards in the country through Phivolcs' official social media accounts, website and applications: HazardHunterPH and Volcano PH Info.

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