State volcanologists again observed volcanic smog or vog over Taal Volcano and within its vicinity, as sulfur dioxide (SO2) emission increased.

The Philippine Institute of Volcanology and Seismology (Phivolcs) said in a bulletin at 8 am on Friday, August 13, that SO2 emission averaged 8,997 tons per day on Thursday, August 12.

That figure is nearly triple the 3,004 tons per day recorded on Wednesday, August 11.

A high level of SO2 indicates magma is relatively nearer the volcano’s surface.

Taal Volcano’s highest-ever SO2 emission was recorded last July 4 at 22,628 tons per day.

Vog, meanwhile, is a type of air pollution resulting from SO2 emission. Phivolcs previously warned that exposure to vog may irritate the eyes, throat, and respiratory tract.

Phivolcs also said on Friday morning that in the past 24-hour period, 18 volcanic earthquakes were recorded. These include:

• 7 volcanic tremors lasting 2 to 16 minutes
• 9 low-frequency volcanic earthquakes
• 2 hybrid events

Low-level background tremor has also persisted since July 7.

In Taal Volcano’s Main Crater Lake, upwelling or the rising of hot volcanic fluids continues. This generated 2,500-meter-high plumes that drifted to the southeast, said Phivolcs.

Taal Volcano was downgraded from Alert Level 3 to Alert Level 2 last July 23, after it showed decreased unrest. At the time, Phivolcs said the volcano could either be further lowered to Alert Level 1 if activity continues to ease, or it may be raised back to Alert Level 3 if activity spikes again.

Under Alert Level 2, Phivolcs reiterated that the following can occur:

• sudden steam- or gas-driven explosions
• volcanic earthquakes
• minor ashfall
• lethal accumulations or expulsions of volcanic gas

Phivolcs said entry into Taal Volcano Island, as well as occupancy and boating on Taal Lake, must remain strictly prohibited. – Rappler.com