MANILA — State seismology agency Phivolcs warned on Friday that the Taal Volcano could have a stronger eruption after it spewed steam and rock fragments hundreds of meters into the sky the day earlier, raising its alert level and prompting thousands to evacuate.

Taal continues to emit smoke, which is caused by gas and water vapor moving up towards its crater, said Phivolcs chief Renato Solidum.

"Sana hindi matuloy ang mas malalakas pang pagsabog, pero and’yan pa rin ‘yan banta na pinapakita ng Taal kasi mas marami pa gas ang nilalabas," he said in a televised public briefing.

(We hope that there won't be a stronger eruption, but the threat from Taal is still there because it continues emitting more gas.)

Taal has been belching sulphur dioxide for several days, creating a thick haze over Metro Manila and several surrounding provinces, and prompting health warnings.

• Taal volcanic smog spreads to Metro Manila, nearby provinces

On Thursday, the volcano that sits in a picturesque lake roared to life with a "short-lived dark phreatomagmatic plume" that rose a kilometer into the air.

That was followed by 4 "short phreatomagmatic bursts" that produced 200-meter-high plumes above the main crater lake, Phivolcs said in a later update.

Taal's last eruption in January 2020 shot ash 15 kilometers high and spewed red-hot lava, crushing scores of homes, killing livestock and sending over 135,000 people into shelters.

SCENARIOS

Video courtesy of PTV

Taal's ongoing release of gas could ease pressure inside the volcano and prevent explosive eruptions. Under Phivolcs' "stand down" procedure," seismologists will have to observe the volcano for some 2 weeks before downgrading its alert level, said Solidum.

Another possible scenario is that a flow of lava could seep from Taal.

"Parang may fireworks lang nang kaunti at dumaloy ang lava," he said.

(It could look like fireworks and lava might flow.)

The third scenario is another eruption, though Phivolcs expects this to be weaker than Taal's 2020 fury, Solidum said.

"Dahil nga de-gas na po ang magma sa mas mababang parte, hindi po namin inaasahan na kasing lakas noong last year, na mabilis na umakyat ang maraming gas kaya malakas ang pagsabog," said the Phivolcs chief.

(Because the magma has degassed in the shallower portion of the volcano, we do not expect that it would be as strong as last year, when that gas rapidly moved up and caused a strong eruption.)

"Kaya lang nga po, mayroon din namang mga scenario na 'pag mayroong bagong supply ng magma galing sa mas malalim na parte... and'yan yong possibility pa rin na magkaroon ng mas malakas na pagsabog kumpara sa kahapon," he added.

(However, there is also a possible scenario that if there is a new supply of magma from deeper, the possibility is there, there could be an eruption stronger than the one yesterday.)

Philvolcs has recorded at least 29 volcanic earthquakes around Taal, the agency said in a bulletin. These quakes were not felt, said Solidum.

But he warned, "Importante po na maging maingat ang mga tao. Kahit po hindi nararamdaman iyong paglindol ay mayroon pong nangyayari d’yan sa volcano island."

(It is important the people are careful. Even if the earthquakes were not felt, there is something going on there at the volcano island.)

The alert for Taal, located about 70 kilometers south of Manila, remained on level 3 on a 5-level scale. This meant "magma extruding from the Main Crater could drive explosive eruption," Phivolcs said in its bulletin.

PALACE MONITORING

The towns of Agoncillo and Laurel in Batangas province, situated on the lake surrounding the Taal volcano, were in danger from eruption and volcanic tsunami, the seismology agency said.

A spokesman for the national disaster agency said its local agents had called an emergency meeting with government officials and emergency services. He estimated nearly 15,000 people lived in the most vulnerable areas.

The evacuation of Agoncillo started late afternoon, Batangas provincial governor Hermilando Mandanas said, with 3,523 families or 14,495 people to be moved to safe areas.

Dump trucks were sent to assist and pay loaders and evacuation centers were being readied, he added.

• Thousands evacuated in Laurel town, mayor says, as Taal spews ash

Malacañang is "closely monitoring the situation," said its spokesman Harry Roque.

The Department of Social Welfare and Development is on heightened alert and has stockpiles of food packs worth P1.4 million and P11 million in non-food items, he said.

The military's Southern Luzon Command has activated joint task force Taal to assist the national disaster agency and local governments, while the police was also put on alert and the coast guard deployed vehicles and personnel for humanitarian assistance, Roque said.

"We ask residents in the areas surrounding the volcano lake to remain vigilant, take precautionary measures, cooperate with their local authorities should the need for evacuation arise," he said in a statement.

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Earthquakes and volcanic activity are not uncommon in the Philippines as it is located in the Pacific "Ring of Fire," where tectonic plates collide deep below the Earth's surface.

The Mayon, Bulusan, Kanlaon, and Pinatubo volcanoes are under alert level 1, said Solidum.

This means seismologists have observed a slight increase in volcanic earthquake and steam or gas activity, as well as sporadic explosions, increase in the temperature of hot springs, and inflation or swelling of the edifice, according to the Phivolcs website.

— With reports from Jamaine Punzalan, ABS-CBN News; Agence France-Presse; Reuters