Phivolcs Director Explains ‘Record-High’ Sulfur Dioxide Emission From Taal This Year
Taal Volcano remains under Alert Level 1 even as it recorded very high sulfur dioxide emissions last Nov. 9, which Phivolcs attributed to continued degassing activities of the volcano.
Despite the record-high emission of sulfur dioxide (SO2) for 2023 last Thursday, Nov. 9, the Philippine Institute of Volcanology and Seismology (Phivolcs) said Taal Volcano remains under Alert Level 1 or “abnormal condition.”
In an interview with “One Balita Pilipinas” on One PH on Friday, Nov. 10, Phivolcs director Teresito Bacolcol said that the latest activity monitored in Taal was due to the continued degassing activities of the volcano.
“Indikasyon lamang ito na patuloy pa rin ang degassing activity o pagre-release ng gasses sa magma chamber ng Taal Volcano. (It is only an indication that degassing activity or the release of gasses from the magma chamber of Taal Volcano is continuing),” he said.
He noted an increase in weak volcanic earthquakes associated with degassing activities, which resulted in the increase in SO2 emissions.
In an advisory on Thursday, Nov. 9, the Phivolcs disclosed that it measured 11,499 tons of SO2 emission from Taal, eclipsing the previous record this year of 9,762 tons of daily SO2emission recorded in Oct. 12.
“Visual monitors show continued pronounced upwelling of volcanic fluids in the Main Crater that generated rather short and weak- to moderate-volume degassing plumes. Strong winds drifted the plumes to the southwest,” Phivolcs’ advisory read.
However, the agency retained Taal under Alert Level 1, “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.”
“At 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 TVI (Taal Volcano Island),” it added.
It recommended the strict prohibition of entry into the TVI, its permanent danger zone, especially the vicinities of the main crater and the Daang Kastila fissure.
It also advised local government units “to continuously monitor and assess volcanic SO2 and vog exposure of, and potential impacts on, their communities and undertake appropriate response measures to mitigate these hazards.”
Vog formation
In its advisory, Phivolcs said it has not monitored any volcanic smog or vog over Taal caldera last Thursday, Nov. 11, but it predicted a possible SO2 accumulation and vog formation the following day.
Bacolcol, however, said told One Balita Pilipinas that no vog has formed the following day. He reiterated its formation is dependent on wind speed, and faster winds mean that the SO2 easily dissipates.
He bared that wind speeds on Thursday and Friday “were fairly fast,” with surface wind speeds reaching up to “four to six meters per second.” This prevented vog formation around Taal Caldera, he added.
However, Bacolcol confirmed that thick vog formations last September can still re-occur. At the time, classes and work in Batangas, Rizal, and Laguna were disrupted after vog was observed around Batangas and Taal Caldera.
“Posible mangyari ‘yon [‘yung vog noong September] kapag may mabagal na hangin at hindi makaangat ang sulfur dioxide dahil sa thermal inversion. Ibig sabihin ng thermal inversion, ‘yung temperatura sa lupa ay mababa… ito ang dahilan kung bakit hindi makaangat ang sulfur dioxide (Vog like in September can re-occur when there are slow winds, and sulfur dioxide are trapped by thermal inversion. Thermal inversion means that ground temperature is low… and that is the reason why sulfur dioxide cannot go up to the atmosphere),” Bacolcol said.
Metro Manila can also be affected by potential vog formation, Bacolcol said. However, he stressed it would only be possible if the wind direction is northbound.
“Pero sa mga buwan na ‘to, ang hangin ay amihan na galing sa northeast papuntang southwest. Kaya kung sakaling may vog man, most likely papunta ito towards the southwest, papalayo sa Metro Manila (Currently, this is the season for trade winds coming from the northeast and onto the south west. So if ever there is vog, most likely it will go southwest, away from Metro Manila)” Bacolcol explained.
Bacolcol also warned against the dangers of vog, which usually contains SO2 that it acidic and can cause irritation in the eyes, throat and respiratory tract. Severity also depends on gas concentration and duration of exposure, he said.
Vulnerable groups include those who are asthmatic or have health or lung disease, as well as the elderly, pregnant women and children.
“So pinapayuhan natin ‘yung ating mga residente na umiwas sa mga aktibidad sa labas… manatili sa loob ng bahay at isara ‘yung pinto. Kung ‘di talaga maiwasan lumabas (We are advising our residents to avoid outdoor activities… to stay indoors and close their doors. If they really need to go out), they should protect themselves by wearing facemasks. N95 if possible,” he said.
