The Philippine Institute of Volcanology and Seismology (Phivolcs) is not expecting a scenario where the Taal Volcano will erupt similar to its January 2020 eruption.

Phivolcs’ Volcano Monitoring and Eruption Prediction Division chief Ma. Antonia V. Bornas said that as early as March, the agency said is not expecting a scenario to happen similar to the eruption last year.

“Noong March pa natin sinasabi na hindi natin ine-expect yung gano’ng klaseng scenario (It was back in March when we said that we are not expecting such scenario),” Bornas said, referring to Taal’s January 2020 eruption.

She explained that before the 2020 eruption, Taal was a “closed system” where the magma stored in the volcano still packed pressure, which led to its strong explosion.

“So iba po ‘yong scenario no, depressurized na ‘yong magma, open system na ang taal (So the scenario is different, the magma is depressurized, Taal is now an open system),” she said in a virtual press briefing.

“Nakakapag-degas na siya ng dere-deretso, at nawawalan siya ng pwersa, naninigas, at hindi nakakapag-ipon ng sapat na gas over pressures (It can now release gas, it is losing strength, stiffening, and unable to store enough gas over pressures),” she added.

But the Phivolcs official noted that the situation can still change if new magma flows out through its old fissure vents.

“Kung magkakaroon ng panibagong intrusion diyan, doon maari tayong magbago ng scenario (If there will be new intrusion there, then the scenario will change),” Bornas said.

Phivolcs director Undersecretary Renato Solidum Jr. noted the different scenarios that occurred during Taal’s eruption in January 2020 and what transpired on Thursday afternoon.

“‘Yung January 2020, sa maliit na explosion, lumaki nang lumaki kasi nga may pressure. Tinanggal natin ang pressure sa crater at ‘yong mas mataas ang pressure na magma ay biglang umakyat (In January 2020, with a small explosion, it got bigger and bigger because there was pressure. We removed the pressure in the crater and the high-pressured magma suddenly went up),” Solidum said.

“Ngayon ay nagde-degas nga, so kakaiba ang panimula tungkol dito, at binanggit na na hindi gano’n ka-explosive ang simula nito kaysa sa last year (It can now release gas, so it has a different beginning, and it's been mentioned that the beginning isn't as explosive as last year),” he added.

The volcano’s main crater generated a “short-lived” dark phreatomagmatic plume that rose up to one kilometer high at 3:16 p.m. on Thursday afternoon. The eruption quickly ended after five minutes.

This led the Phivolcs to raise the alert status of Taal to Alert Level 3 or “magmatic unrest” from Alert Level 2 or “increasing unrest.”

“This means that there is magmatic intrusion at the Main Crater that may further drive succeeding eruptions,” the agency said.