Taal Volcano let off a total of 175 volcanic earthquakes over a 24-hour period on Friday, including 131 tremors lasting from one to 15 minutes, the Philippine Institute of Volcanology and Seismology (Phivolcs) reported on Saturday.
The number is higher than the 110 volcanic quakes recorded on Thursday.
These earthquakes are caused by movements or eruptions of magma from the volcano, compared to tectonic quakes which are caused by fault movements.
Taal Volcano has been under alert level 2 (increased unrest) since March 9.
“Phivolcs determines the appropriate (alert) level for a volcano depending on the earthquakes recorded, not only based on the number but also the type of earthquakes, location, depth and energy of the quakes,” Phivolcs Director Renato Solidum Jr. said.
He added that other parameters, such as ground deformation, the chemistry of gases and water, and surface manifestations are also being looked at.
“Taal Volcano is currently at alert level 2, and if current unrest persists, this can lead to an eruption,” Solidum warned.
For the past 24 hours, Phivolcs has observed moderate emission of steam-laden plumes that rose 80-100 meters high. Sulfur dioxide emission that averaged 603 tons/day was measured on Friday.
Meanwhile, temperature highs of 71.8°C and pH of 1.59 were last measured from the main crater lake on March 4 and February 12, respectively.
Phivolcs reiterated that entry into Taal Volcano Island, a permanent danger zone (PDZ), must be strictly prohibited.
Local government units were also advised to continuously assess and strengthen the preparedness of previously evacuated barangays around Taal Lake in case of renewed unrest. SOVEREIGNPH