Phreatic eruption, vog reported in Taal Volcano — PHIVOLCS

A minor phreatic eruption and vog were observed over Taal Volcano on Thursday, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) said on Friday.

In its bulletin, PHIVOLCS said the phreatic eruption lasted six minutes.

Phreatic eruptions are steam-driven explosions that occur when water beneath the ground or on the surface is heated by magma, lava, hot rocks, or new volcanic deposits, according to PHIVOLCS.

A voluminous emission of plumes reaching up to 2,800 meters tall was monitored from Taal Volcano, which drifted to the northeast and southwest directions.

The volcano emitted 2,256 tons of sulfur dioxide gas on Wednesday and its Main Crater Lake had an upwelling of hot volcanic fluids.

Vog or volcanic smog was observed in Taal Volcano. Vog is composed of sulfur dioxide gas and other volcanic gasses which mix with atmospheric oxygen, moisture, dust, and sunlight, PHIVOLCS said.

PHIVOLCS in a statement on Thursday said “the volcanic smog observed today is primarily concentrated over the Taal Caldera region based on visual monitors.”

“The smog observed in Metro Manila may still be attributed to anthropogenic pollutants. Furthermore, wind speed is low (less than 1 m/s) based on the meteorological data of PAGASA, thus decreasing the likelihood of volcanic gasses to reach the Metropolitan region,” it added.

Afternoon face-to-face classes were suspended in several areas on Thursday due to vog following the recent activity of Taal Volcano:

• Balayan, Batangas -- all levels, private and public
• Nasugbu, Batangas -- all levels, private and public
• Lian, Batangas -- all levels, private and public

A long-term deflation of the Taal Caldera and a short-term inflation of the general northern and southeastern flanks of the Taal Volcano Island were also observed.

No volcanic earthquakes were recorded in Taal Volcano, according to PHIVOLCS.

Taal Volcano is still under Alert Level 1, which means the volcano is in abnormal condition and should not be interpreted to have ceased unrest nor ceased the threat of eruptive activity.

The possible hazards under Alert Level 1 are sudden steam-driven or phreatic explosions, volcanic earthquakes, minor ashfall and lethal accumulations or expulsions of volcanic gas.

People are prohibited from entering the Taal Volcano Island, permanent danger zone or PDZ, especially the vicinity of the Main Crater and the Daang Kastila fissure.

Flying close to the volcano is also prohibited. — Joviland Rita/RSJ, GMA Integrated News