PHIVOLCS: Taal Volcano smog duration can't be predicted

The duration of the volcanic smog due to Taal Volcano’s activity, which has caused class suspensions in many areas in Luzon, including Metro Manila, on Friday, cannot be predicted, according to the Philippine Institute of Volcanology and Seismology (PHIVOLCS).

“As long as Taal Volcano is spewing out sulfur dioxide, this will be a recurring threat,” PHIVOLCS director Dr. Teresito Bacolcol told GMA Integrated News’ Unang Balita in an interview on Friday.

“Iyong duration po ng (the duration of) sulfur dioxide emission cannot be predicted due to unprecedented levels in the recorded history,” he added.

Bacolcol said in the case of Miyake-jima in Japan, it took around five years for its sulfur dioxide emission to slow down.

For Taal Volcano, Bacolcol said the direction of the sulfur dioxide emission was drifting towards the west affecting Tuy, Calaca, Balayan, and Nasugbu towns in Batangas. He said local governments have the discretion to implement evacuation of residents if needed.

In Tuy, over 40 students were hospitalized due to chest tightness or pain, dizziness, itchy throat and skin, the Batangas Provincial Disaster Risk Reduction and Management Office said on Thursday.

The smog also resulted in flight cancellations for the day.

Bacolcol advised the public to avoid outdoor activities, close their doors and windows, and wear a face mask or N95 mask when going outside. He advised drinking a lot of water to flush sulfur dioxide.

He said he is hoping for rains that may flush out the smog in affected areas.

According to Bacolcol, vog or volcanic smog is a mixture of water vapor and particulates with sulfur dioxide. He said steam plumes emit from the volcano when hot volcanic materials touch water.

He said there is no problem if the steam plumes rise and dissolve.

“But there are times that the sulfur dioxide and water vapor will stay on the lower level kapag meron pong tinatawag nating thermal inversion — so this is when the temperature near the ground is low at hindi po makaangat iyong steam plumes natin,” The PHIVOLCS official said.

(But there are times that the sulfur dioxide and water vapor will stay on the lower level when there is a thermal inversion — this is when the temperature near the ground is low and the steam plumes cannot rise.)

“There are times, depende po sa prevailing wind conditions, pinapadpad po ito sa ibang lugar at ito po ay naaamoy ng mga tao,” he added.

(There are times, depending on prevailing wind conditions, the smog drifts to different areas and people in those areas can smell it.)

Bacolcol noted that volcanic smog is not an indication to raise the alert level status of Taal Volcano, which is presently under Alert Level 1, signifying "low level unrest."

In its bulletin on Friday, PHIVOLCS said only five volcanic tremors lasting up to 575 minutes were recorded in the volcano from 5 a.m. on Thursday to 5 a.m. on Friday.

The sulfur dioxide emission increased from 4,322 tonnes on Tuesday to 4,569 tonnes on Thursday.

Aside from the vog, PHIVOLCS also noted a pronounced upwelling of hot volcanic fluids in the Main Crater Lake.

A voluminous emission of plumes up to 2,400 meters tall were seen from the Taal Volcano drifting to the west-southwest and southwest directions.

PHIVOLCS said possible hazards that can occur due to the volcano’s activity are steam-driven or phreatic or gas-driven explosions, volcanic earthquakes, minor ashfall, and lethal accumulations or expulsions of volcanic gas.

Because of this, entry into Taal Volcano Island (Permanent Danger Zone or PDZ), especially the Main Crater and Daang Kastila fissures, is prohibited, PHIVOLCS added.

Occupancy and boating on Taal Lake as well as flying any aircraft close to the volcano are also not allowed, it also said. —KBK, GMA Integrated News