Phivolcs needs two weeks’ observation of Taal Volcano before lowering alert level

Published January 17, 2020, 12:00 AM

by manilabulletin_admin

By Alexandria Dennise San Juan

State volcanologists said it will take at least two weeks of close observation to check if there is a downward trend on the activities of Taal Volcano before deciding whether to lower its alert level.


“Usually, may dalawang linggo tayong observation period para makita kung talagang pahupa na ang volcano,” Philippine Institute of Volcanology and Seismology (Phivolcs) director Renato Solidum said Friday.

(Usually, we have a two-week observation period to see if volcanic activity is subsiding.)

“Definitely kasi, may nakikita pa kaming pagkilos ng magma sa ilalim ng Taal, so usually, two weeks observation period ang ginagawa natin para lang maiwasan ‘yung resurgence ng activity ng isang bulkan at magkaroon muli ng pagsabog,” he added.

(Definitely we are still seeing movement of magma under Taal, so we usually give a two-week observation period to avoid the resurgence of activity that could lead to another eruption.)

Phivolcs has been monitoring lesser activities on the surface crater of Taal Volcano six days after its phreatic or steam-driven eruption on Sunday (Jan. 12) that surprised thousands of unaware residents, forcing them to immediately evacuate to safer areas.

In the latest update on the volcano’s activity, the Phivolcs chief said “steady steam emission and infrequent weak explosions” have been observed in the main crater in the past 24 hours.

These activities generated at least 100- to 800-meter tall dark gray ash plumes which blanketed lakeshore communities in the southwest to west of the main crater.

Despite the “relatively lull” period of Taal Volcano as observed in its surface crater, Solidum warned there is still a threat of hazardous explosive eruption as movement of magma underneath Taal continues.

Intense tremors persist

According to Solidum, 65 volcanic tremors were plotted near Taal from Thursday morning to Friday morning, two of which were registered at magnitudes 1.3 to 3.1 and were both felt at Intensity I.

This brings to 634 the total volcanic quakes recorded by the Philippine Seismic Network since the afternoon of Jan. 12, 174 of which were registered at magnitudes 1.2 to M4.1 and were felt at Intensities I to V.

The Taal Volcano Network, which can detect low-frequency tremblors, already plotted a total of 944 volcanic quakes within the volcano island.

Phivolcs’ Volcano Monitoring and Eruption Prediction chief Mariton Bornas said such intense seismic activity likely signifies that there is continuous magmatic intrusion beneath the Taal edifice, which may lead to further eruptive activity.

Existing fissures have widened

Bornas also mentioned that the existing fissures or cracks on the ground identified in several barangays of Lemery, Agoncillo, Talisay, and San Nicolas in Batangas have been observed to widen by a few centimeters.

Phivolcs added that a steaming fissure has been found on the northern slopes of Taal Volcano Island, while the receding of the shoreline has been observed in the whole of Taal Lake.

“Lumalaki ng kaunti yung mga bitak na nagsasaad na may deformation, nagde-deform pa rin ang caldera. Mataas ang sulfur dioxide, at may nare-record pa rin tayong mga volcanic earthquakes at low-frequency quakes. Ito talaga ang signal na may gumagalaw na magma paakyat ng bulkan,” Bornas said.

(The fissures have widened, signifying a deformation of the caldera. Sulfur dioxide emissions are still high, and we are continuously recording volcanic quakes and low-frequency quakes. These parameters show there is still an upward movement of magma inside the volcano.)

“Hindi pa po nawawala ang panganib, nandyan pa rin ang possibility ng malakas na pagsabog.”
(Danger is imminent as the possibility of a hazardous explosive eruption is still there.)

Continuous monitoring

According to Bornas, it is hard to predict the trend of Taal given its apparent mood swings and lesser surface activity in the recent days.

“Hindi pa rin po natin masasabi at this point kung lalakas pa ba o hihina. Kailangan nating tingnan araw-araw kasi anytime puwedeng magbago, hindi natin masabi kung lalakas o hihina.”
(We cannot say whether Taal Volcano’s activity will further decrease or increase. We need to monitor that everyday because it might change.)

Bornas said volcanologists are continuously monitoring the activity of the volcano to observe its overall trend and provide accurate data and advisory to the public.

“Ito ‘yung medyo mahirap na bahagi ng ating trabaho. Kailangan nating tingnan kung ano ang nangyayari sa bulkan sa araw-araw, pwede kasing magbago bigla dahil nakabukas na ang bulkan, pwede nang may sumuot na mas malaking magma at pumutok anytime.

“Kailangan pa nating tingnan ang kalagayan ng Taal, ‘yung overall trend niya. Kailangang maging maingat kami sa pagbibigay ng data kasi ang katumbas nun ay buhay.”

(This is the hard part about our job. We need to monitor the volcano daily, because it can change anytime because the volcano is venting, magma can pass through the channels and the volcano can erupt anytime. We need to keep monitoring Taal’s condition, its overall trend. We need to be careful when sharing data because lives are at stake.)

Still on Alert Level 4

Alert Level 4 remains in effect over Taal Volcano, a notch below the highest alert level, which means a hazardous explosive eruption is possible within hours to days.

The state volcanology bureau strongly reiterates total evacuation of Taal Volcano Island and the high-risk areas identified in the hazard maps within the 14-kilometer radius from Taal Main Crater, as well as along the Pansipit River Valley where fissuring has been observed.

Residents around Taal Volcano are also advised to guard against the effects of heavy and prolonged ashfall.

Civil aviation authorities were also advised to remind pilots to avoid the airspace around Taal Volcano as airborne ash and ballistic fragments from the eruption column pose hazards to aircraft.

According to Phivolcs, Taal is the second most active volcano in the country in terms of number of eruptions, with at least 33 eruptions recorded from 1572 to 1977.

Although tagged the world’s smallest volcano, Taal is also one of the deadliest following its violent eruptions in 1754, 1911, and 1965, leaving thousands of casualties in the wake of its various volcanic hazards.

Read more: Taal alert level 4 up after phreatic eruption