The Philippine Institute of Volcanology and Seismology (Phivolcs) said in its 8 am bulletin on Wednesday that it observed “moderate to voluminous emission of white to dirty white steam-laden plumes 600 to 800 meters tall” from the main crater during the past 24 hours.
The tallest plumes stated in Phivolcs’ bulletin a day ago, on Tuesday, January 28, were also 800 meters tall.
Meanwhile, the sulfur dioxide (SO2) emission was measured at an average of 64 tons per day, in contrast to Tuesday’s, when the level of SO2 was too low to be detected by instruments.
But Phivolcs confirmed to Rappler in a phone interview that 64 tons remains a low level of SO2.
SO2 emission previously averaged as high as thousands of tons per day, when Taal had been under Alert Level 4.
SO2 is a major gas component of magma. More SO2 is released when magma is near the surface of a volcano.
As for volcanic earthquakes, the Philippine Seismic Network plotted only 3 volcanic earthquakes from 5 am on Tuesday to 5 am on Wednesday. These were magnitudes 1.7 to 2.1, with one felt event at Intensity III.
Since 1 pm of January 12 – when the Taal unrest began – to present, the Philippine Seismic Network has plotted 760 volcanic earthquakes. Of these, 177 were magnitudes 1.2 to 4.1 and were felt at Intensities I to V.
The Taal Volcano Network, which can record small earthquakes undetectable by the Philippine Seismic Network, recorded 123 volcanic earthquakes in the past 24 hours.
These included 3 low-frequency events, which are “caused by cracks resonating as magma and gases move toward the surface,” according to the United States Geological Survey.
“These earthquakes signify magmatic activity beneath the Taal edifice that could lead to eruptive activity at the main crater,” Phivolcs said, reiterating that while the chances of a hazardous eruption may have decreased, the unrest has not totally stopped.
The following could still happen, which would threaten Taal Volcano Island and lakeshore areas in the province of Batangas:
- sudden steam-driven and even weak phreatomagmatic explosions
- volcanic earthquakes
- lethal volcanic gas expulsions
These areas are within a 7-kilometer radius from the main crater, which is Phivolcs’ recommended danger zone while Taal is under Alert Level 3. (WATCH: Police uphold duty to others, even while affected by Taal Volcano’s eruption)
If volcanic activity continues to ease, Taal could be further downgraded to Alert Level 2. But if it escalates, Alert Level 4 may be raised again.
The highest possible status is Alert Level 5. It would mean that a hazardous eruption is already in progress. – Rappler.com