Watch more in iWantv or TFC.tv

'Napakabilis ng pagbabago ng kanyang kundisyon."

This is how the country's chief seismologist described the rapid escalation of volcanic activity that prompted the Philippine Institute of Volcanology and Seismology to raise Alert Level 4 over Taal Volcano, warning of a possible hazardous eruption.

Phivolcs chief Renato Solidum said the agency has monitored an increase in Taal volcanic activity starting March 28, 2019 but confirmed there was a rapid escalation over the weekend, starting with the emission of a giant column of steam and ash and a series of volcanic tremors.

• Alert level 4 raised over Taal, volcanic tsunami possible: PHIVOLCS

"If there was just a lot of quakes and phreatic eruptions, the escalation would be slower and people who were unaware of the volcanic activity would not be surprised," he told radio DZMM.

Solidum said raising Alert level 4, warning of a possible hazardous explosive eruption within hours to days, was necessary due to an increase in volcanic activity including volcanic tremors.

He noted that rising magma could activate fissures, which causes earthquakes. He said the spewing of lava fountains in Taal's crater early Monday is also a manifestation of magma rising.

• Taal spews lava fountains

"Worst case scenario would be that aside from spewing ash upwards, there would be rocks falling and ash crossing the lake. That is the worst case scenario and that will happen if there will be a lot of magma coming from the volcano," he said.

He warned that those living in the mainland across Taal Lake to take precautions and follow the 14-kilometer evacuation advisory from Phivolcs.

"Worst case scenario is a pyroclastic density current,which is a cloud of hot gas and volcanic matter moving horizontally to the mainland. Based on our mapping, it could reach up to 14 kilometers from the main crater, affecting coastal towns around the volcano plus Lemery and Taal," he said.

Phivolcs has advised total evacuation of residents in the Taal Volcano island and areas within a 14-kilometer radius from the main crater.

"Areas in the general north of Taal Volcano are advised to guard against the effects of heavy and prolonged ashfall. Civil aviation authorities must advise aircraft to avoid the airspace around Taal Volcano as airborne ash and ballistic fragments from the eruption column pose hazards to aircraft," the agency said.

A volcanic tsunami may occur in caldera lakes, like Taal Lake, when water is displaced by deformation of the lake floor due to rising magma, the agency said on its website.

It may also be caused by pyroclastic materials flowing down from the volcano into the lake, or landslides caused by volcanic activity.

In the interview, Solidum warned the volcano has no pattern of eruptions. "Each volcano is different," he said.

He noted that Mt. Pinatubo's escalation of volcanic activity took months in between alert levels. In comparison, he said Taal's volcanic activity rapidly escalated starting 11 a.m. Sunday.

He said in terms of explosiveness, Pinatubo's eruption was stronger but Taal's volcanic activity is more dangerous "because there are more people living near the crater."