The Philippine Institute of Volcanology and Seismology (Phivolcs) on Wednesday, August 3 observed an increase in sulfur dioxide (SO2) emission in the Taal Volcano.

“A total of 12,125 tons per day of volcanic sulfur dioxide or SO2 gas emission from the Taal Main Crater was recorded this morning, the highest since the alert status was lowered to Alert Level 1 on July 11, 2022,” Phivolcs said in an advisory issued at 2 p.m., Wednesday.

“SO2 flux since July 15, 2022 has averaged 4,952 tons per day, an increase from the average of 1,289 tons per day between May and mid-July 2022,” it added.

Phivolcs warned the public against airborne volcanic gas that could be drifted to the northwest of the Taal Volcano Island, based on air parcel trajectory data from the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA).

The State volcanologists said that the increased degassing has been visible as upwelling in the Taal’s main crater lake and voluminous steam-rich plume activity in the past three days.

Due to Taal’s degassing, Phivolcs said that “volcanic smog” or “vog” was observed on August 2 and August 3 over the western Taal Caldera.

“Heavy” vog has reached Laurel town and Brgy. Banyaga in Agoncillo town, in the province of Batangas.

There have also been damages to vegetation, as reported by the municipal officials.

Sulfur stench was also reported by residents of Tagaytay City and Brgy. Bugaan East in Laurel town.

“A total of nine low-frequency events that included tremor, eight to 12 minutes in duration, were recorded in the past observation period, more than the baseline level of volcanic earthquakes,” Phivolcs said.

‘Vog’ warning issued

Phivolcs warned the public against vog as it consists of fine droplets containing volcanic gas such as SO2, which is acidic and can cause irritation of the eyes, throat and respiratory tract in severities depending on the gas concentrations and durations of exposure.

People who may be particularly sensitive to vog are those with health conditions such as asthma, lung disease and heart disease, the elderly, pregnant women and children.

For communities that can be affected by vog, Phivolcs advised them to limit their exposure.

“Avoid outdoor activities, stay indoors and shut doors and windows to block out vog,” it said.

“Protect yourself. Cover your nose, ideally with an N95 facemask. Drink plenty of water to reduce any throat irritation or constriction. If belonging to the particularly sensitive group of people above, watch over yourself and seek help from a doctor or the barangay health unit if needed, especially if serious effects are experienced,” it added.

Taal remains under Alert Level 1

Phivolcs reminded the public that Alert Level 1 prevails over Taal Volcano, which means that it is still in abnormal condition and should not be interpreted to have ceased unrest nor ceased the threat of eruptive activity.

“Should an uptrend or pronounced change in monitored parameters forewarn of renewed unrest, the Alert Level may be raised back to Alert Level 2,” it said.

“Conversely, should there be a return of monitoring parameters to baseline levels after a sufficient observation period, the Alert Level will be further lowered to Alert Level 0,” it pointed out.

Under Alert Level 1, sudden steam-driven or phreatic explosions, volcanic earthquakes, minor ashfall and lethal accumulations or expulsions of volcanic gas can occur and threaten areas within the Taal Volcano Island (TVI).

“Phivolcs strongly recommends that entry into TVI, Taal’s permanent danger zone or PDZ, especially the vicinities of the main crater and the Daang Kastila fissure, must remain strictly prohibited,” it said.