The Philippine Institute of Volcanology and Seismology (Phivolcs) said it has recorded a total of 466 volcanic earthquakes since 1 pm last Sunday, January 12. Of these tremors, 156 were felt with intensities ranging from Intensity I to V.
Just from 5 am on Tuesday, January 14, to 5 am on Wednesday – or a 24-hour period – there were 159 volcanic earthquakes. Of these, 28 were felt with intensities ranging from Intensity I to III.
"Such intense seismic activity probably signifies continuous magmatic intrusion beneath the Taal edifice, which may lead to further eruptive activity," warned Phivolcs in an 8 am bulletin on Wednesday.
When it comes to the surface activity of the Taal Volcano's main crater, or what people can see, it is "generally weaker" but "continuous."
"This ongoing eruption generated dark gray steam-laden plumes that reached approximately 1,000 meters high and dispersed ash to the southwest of the main crater," Phivolcs said.
"Residents around Taal Volcano are advised to guard against the effects of heavy and prolonged ashfall. Civil aviation authorities must advise pilots to avoid the airspace around Taal Volcano as airborne ash and ballistic fragments from the eruption column pose hazards to aircraft," Phivolcs reiterated.
The agency also said new fissures or cracks were spotted on the ground in Batangas, particularly in these areas:
"A fissure transected the road connecting Agoncillo to Laurel, Batangas," added Phivolcs.
Because of the risks, Phivolcs emphasized that there must be "total evacuation" of Taal Volcano Island as well as high-risk areas within a 14-kilometer radius from the main crater and "along the Pansipit River Valley where fissuring has been observed." (READ: Lorenzana urges Duterte: Declare Taal 'no man's land')
"Iba 'yung visual activity na nangyayari sa ibabaw, iba 'yung nangyayari sa ilalim. Meron pa ring...[magmatic] intrusion at 'yun 'yung dahilan ng mga lindol, ng mga bitak," said Phivolcs Director Renato Solidum in a briefing on Wednesday morning.
(The visual activity happening at the surface is one thing, the activity beneath is another matter. There's still magmatic intrusion and that is what's causing the volcanic earthquakes, the fissures.)
"Habang hindi natin binababa ang alerto, i-maintain natin 'yung distansya na 14 kilometers [from the main crater]," Solidum added.
(Since we haven't lowered the alert level, let's maintain the distance of 14 kilometers from the main crater.)
The ongoing unrest of the Taal Volcano began with a phreatic or steam-driven eruption at 1 pm last Sunday. This progressed to a magmatic eruption as lava fountains emerged in the early hours of Monday, January 13.
The escalation was quick as Alert Levels 2, 3, and 4 were raised in a matter of hours on Sunday. The highest possible alert level is 5, which means a hazardous eruption is already in progress. (READ: TIMELINE: Taal Volcano eruptions since 1572)
Batangas has been under a state of calamity since Monday. The number of evacuees rose to more than 24,000. (WATCH: Taal Volcano tremors damage homes in Batangas)