By Alexandria Dennie San Juan and Hanah Tabios
An explosive eruption of Taal Volcano is imminent as magma continues to rise beneath, Philippine Institute for Volcanology and Seismology (Phivolcs) director Renato Solidum Jr. said on Wednesday.
Dr. Renato Solidum
(MANILA BULLETIN FILE PHOTO)
Solidum warned the public not to be confused by the weaker activity seen in the surface crater of Taal Volcano, noting that frequent tremors and fissures near Taal signify continuous magma movement underneath.
“Ihihiwalay natin 'yung nakikita natin sa ibabaw ng Taal, sa nangyayari sa ilalim (Let us separate what we are seeing on Taal's surface from what is happening underneath),” Solidum said on Wednesday.
“Hindi nanahimik ang bulkan. Patuloy 'yung activity nito sa ilalim. Yung nangyayari sa ibabaw ay consequence pa ‘nung nangyari noong Linggo, pero ngayon ay mayroon pa ring dagdag na intrusion (The volcano is not silent. Activity continues beneath it. What is happening now on the surface is a consequence of what happened on Sunday, but now there is the addition of magma intrusion),” Solidum said.
In its latest bulletin, the state seismology bureau said Taal Volcano displayed a “continuous but generally weaker eruption of the main crater due to magmatic and hydrovolcanic processes.”
Since Tuesday night, Taal continued to spew dark gray steam-laden plumes or ash clouds reaching up to 1,000 meters high that blanketed areas on the southwest of the main crater.
Despite the slower volcanic activity of Taal, Solidum strongly reiterated total evacuation of the volcano island and high-risk areas identified on the hazard maps within the 14-kilometer radius from the volcano's main crater.
Mandatory evacuation
With Taal’s imminent explosive eruption, the local government units (LGUs) of 12 towns and two cities of Batangas were advised to immediately conduct mandatory evacuation as the areas are now susceptible to ballistic projectiles, base surges, and volcanic tsunami.
The Department of the Interior and Local Government Unit (DILG)-Batangas issued the advisory Wednesday based on Phivolcs assessment.
Covered by the mandatory evacuation are:
- Talisay
- Sta. Teresita
- Taal
- San Nicolas
- Mataas na Kahoy
- Malvar
- Lemery
- Laurel
- Cuenca
- Balete
- Agoncillo
- Alitagtag
- City of Tanauan
- Lipa City
Residents in these localities were instructed to coordinate with their LGUs and local disaster risk reduction and management (DRRM) officers for further instructions. These include:
Experts defined ballistic projectiles as volcanic materials directly ejected from the volcano’s vent. These are highly destructive materials that can endanger life and property due to force of impact.
Base surges, in simple terms, is like a landslide composed of solid debris from the volcano and moves radially outward at high speed originating from the base of a vertical eruption column. Its simple Filipino definition would be “mga rumaragasang mainit na bato na nanggagaling sa paanan ng bulkan.”
Several barangays in at least 12 cities and municipalities in Calabarzon also experienced power outage due to Taal’s eruption. The affected barangay are located in Lipa, Tanauan, Laurel, Talisay, and Lemery in Batangas; Amadeo, Tagaytay, Alfonso, Indang, and Mendez in Cavite; and Calamba and Cabuyao in Laguna.
READ MORE: 12 towns, 2 cities in Batangas under mandatory evacuation
466 quakes plotted
In a press conference on Wednesday, Solidum said more volcanic quakes were plotted near Taal since its phreatic or steam-driven eruption last Sunday.
Based on the monitoring of Phivolcs Seismic Networking, there were 159 tremors recorded from 5 a.m. on Tuesday to 5 a.m., Wednesday, 28 of which were felt with intensities ranging from Intensity I to III. This brings the total number of tremblors recorded to 466 after the eruption on Sunday.
More fissures observed
More fissures or cracks on the ground were also observed in several barangays in different towns of Batangas due to the series of quakes felt in the area.
These were found in the barangays of Sinisian, Mahabang Dahilig, Dayapan, Palanas, Sangalang, Poblacion, and Mataas na Bayan in the municipality of Lemery; Pansipit, and Bilibinwang in Agoncillo; Poblacion 1, Poblacion 2, Poblacion 3, Poblacion 5, in Talisay; and Poblacion in San Nicolas.
A fissure was also documented on the road connecting the towns of Agoncillo and Laurel.
Phivolcs' Volcano Monitoring and Eruption Prediction Division chief Mariton Bornas said fissures are caused by magma pushing its way out of Taal Volcano, and often appear before an explosive eruption and then subside after it is over.
Bornas referred to the 1911 eruption of Taal when fissures were also found on the same areas where the new cracks were recently spotted, before the volcano's major eruption.
She said after the 1911 eruption, ground subsidence occurred in places where fissures were observed, which caused many houses and building to collapse due to the lowering of the land surface.
“Noong 1911 kasi, mabilis ang pangyayari. Nagkaroon ng fissuring, then eruption, then subsidence. Iba kasi ang phasing ngayon (In 1911, things happened so fast. There was fissuring, then eruption, then subsidence. The phasing of Taal's activity is different now),” Bornas said.
READ MORE: Phivolcs: New fissures in towns around Taal could lead to ground subsidence; residents warned to evacuate
Explosive eruption
These stronger and frequent quakes, and the increasing number of fissures, Solidum said, means there is a continuous magmatic intrusion beneath the Taal edifice. The continuous movement of magma beneath Taal may lead to further explosive eruption.
Despite these signs, Solidum said the eruption of Taal is still unpredictable just like with any other active volcano, even if it is one of the most instrumented volcanos in the country.
Phivolcs said again that volcanic threats still persist and that residents should not let their guard down and avoid going back to their houses, especially if they are living within the danger zone.
Civil aviation authorities were also advised to warn the aviation industry to avoid the airspace around the volcano as airborne ash and ballistic fragments from the eruption column pose hazards to aircraft.
Apart from prolonged ash fall, residents were also warned of other deadly volcanic hazards that Taal could produce during its eruption such as volcanic tsunamis, base surges, and mudflow.
Taal Volcano's sudden eruption on Sunday surprised thousands of unaware residents and tourists visiting the picturesque lake.
Phivolcs said Taal has not erupted since 1977, but there was volcanic unrest recorded in 2011, 2012, and 2014.
Taal is the second most active volcano in the country in terms of number of eruptions with at least 34 eruptions recorded since 1572.
Although tagged the world's smallest volcano, Taal is also one of the deadliest following its violent eruptions in 1754, 1911, and 1965 that left thousands of casualties in the wake of various volcanic hazards.
River dries up
Meanwhile, fear gripped Taal residents after a portion of the Pansipit River that runs in the town suddenly dried up early Wednesday morning, triggering speculations that the Taal Volcano is gathering strength for a more destructive eruption.
“Kaninang umaga lang ‘yan. Kahapon mataas pa ang tubig, lagpas tao (It happened just this morning. Water level Tuesday was still high)” Lolo Peping, 74, told the Manila Bulletin.
So why did a portion of the river, which hosts a regular fluvial parade, suddenly dry up?
Dr. Winchell Sevilla, of the Phivolcs Volcano Monitoring Department explained that what happened at the Pansipit River is indeed Taal Volcano eruption-related.
He said that since they have been monitoring magma activity inside the volcano, the tendency is for the ground to swell because of the magma accumulation.
The areas where the ground swelling are monitored are in Lemery, Taal and other areas which are close to the Taal Volcano.
“And since the natural flow of water in the river is that it goes to the lower areas, a portion of the Pansipit River dried up possibly because of the swelling or bulging of the ground in the area,” Sevilla told the Manila Bulletin in an interview.
As such, the natural flow of water at the Pansipit River at the portion of Barangay Tatlong Maria in Taal was disturbed and is no longer accessible to water because the area suddenly went up.
Another explanation, which is unlikely according to Sevilla, is that there is a blockage that hinders the flow of water from the supply.
So where did the water go?
One explanation is that the water was stuck in the lower area since its natural flow was disturbed by sudden swelling of the ground.
Another logical explanation, according to Sevilla, is that water that was supposed to flow along the Pansipit River was absorbed by the fissures that were monitored in the past days.
Lolo Peping, the oldest fisher in the area, said they caught some 10 tubs of various live fish, including tilapia and milkfish, a day before the river dried up.
READ MORE: Portion of Pansipit River in Taal dries up; Phivolcs explains why
Dead fish surface
In Barangay Buso-Buso in Laurel town, a fisherman said Wednesday that they had been recovering tubs of dead milkfish since Tuesday on the coast of Taal Lake.
They believed the temperature of the water which rose due to the eruption of the volcano killed the fish.
Residents of the island-village at the foot of Taal said they found their animals already dead and hardened by thick mud, which was caused by volcano ash and rainfall.
A group of men in Barangay Sala in Balete was trying to rescue more animals in Barangay Banga, Talisay, but they were prohibited by the Coast Guard.
“Siguro may isang daan pa ang mga kabayo doon... Wala na silang makain,” John Paul Silva, 18, a resident who volunteered rescuing animals, told the Manila Bulletin.
Motorists, including mediamen, from Tanauan going to Agoncillo could no longer push through as the Barangay Buso-Buso in Laurel, a town near Taal Volcano, was already placed on lockdown. Only personnel of the Department of Public Works and Highways clearing the roads and several police were seen along Tanauan-Talisay Road.
Residents trying to return home to get their belongings after they were evacuated also failed to pass through.
“Sabi naman maglalakad na lang po kami pa Agoncillo, pero di kami pinayagan (We were told that we can proceed to Agoncillo by foot, but eventually we were not allowed),” Anna Marie Vergara, 20, said.
(With reports from Aaron B. Recuenco, Marting A. Sadongdong, and Joseph Pedrajas)
READ MORE: Taal Volcano eruption already causing swath of destruction
