Nearly two weeks since Alert Level 4 was raised for Taal Volcano in Batangas, the period of unrest continues.
The Philippine Institute of Volcanology and Seismology (Phivolcs) said in its 8 am bulletin on Saturday, January 25, that “weak to moderate emission of white steam-laden plumes” persisted from the main crater in the past 24 hours.
The plumes were 100 to 800 meters high, compared to 50 to 500 meters high stated in the previous bulletin on Friday, January 24.
Taal also continues to emit sulfur dioxide (SO2), a major gas component of magma. This indicates that magma is already at a shallow level of the volcano or is moving toward the surface.
SO2 emission was measured at an average of 409 tons per day, higher versus the previous figure of 224 tons per day.
More volcanic earthquakes were recorded too, using the Philippine Seismic Network, which covers the whole country, and the Taal Volcano Network, which includes small earthquakes undetected by the former.
The Philippine Seismic Network has plotted 744 volcanic earthquakes since 1 pm of January 12, when the unrest began. Of these, 176 were magnitudes 1.2 to 4.1 and were felt at Intensities I to V.
From 5 am on Friday until 5 am on Saturday, there were 6 volcanic earthquakes plotted at magnitudes 1.5 to 2.3, with no felt event.
Meanwhile, the Taal Volcano Network recorded 420 volcanic earthquakes, including 11 low-frequency earthquakes, just in the past 24 hours.
According to the United States Geological Survey, low-frequency earthquakes “are caused by cracks resonating as magma and gases move toward the surface.”
“Seismic activity likely signifies magmatic intrusion beneath the Taal edifice that may lead to eruptive activity,” Phivolcs said.
Alert Level 4 means a hazardous eruption is “imminent” or may occur “within hours to days.”
Phivolcs reiterated 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.
The National Disaster Risk Reduction and Management Council said on Saturday that the Taal unrest has affected at least 90,533 families or 348,563 persons