Flying rocks at a speed of over 60kmh – what could happen if Taal erupts 2
A fisherman in Taal lake casts his net with Taal Volcano in the background on June 15, 2021. Photo by Val Cuenca, ABS-CBN News File

Flying rocks at a speed of over 60kmh – what could happen if Taal erupts

 Is there a possibility that the Taal Volcano will erupt like last year? What is its possible major hazard? Here are answers from PHIVOLCS officer-in-charge Renato Solidum Jr.  
RHIA GRANA | Jul 10 2021

Just as people keep watch over the latest news about the country’s second most active volcano, Philippine Institute of Volcanology and Seismology (PHIVOLCS) officer-in-charge Renato Solidum Jr. stays up late to monitor any recent developments in Taal. Thursday night, the geologist stayed up late for another good reason—to answer questions about the topic that has everyone on edge. The PHIVOLCS chief was a guest on Monster Radio’s “Heard on Thursdays” which is hosted by JC Tevez and here’s what he has to say. 


On what those alert levels mean

PHIVOLCS sets specific alert levels for every volcano it monitors. The levels starts with 0 which is normal, to 5 which is the highest level of activity—this is when it’s already erupting explosively and there’s danger that it can harm people.

As of this writing, the alert level in Taal has been raised to 3. This means the magma has reached the surface and would produce explosions. “These explosions would all depend on how much gas the magma contains within it because the gas will propel the explosion,” Solidum explained.

He likened a volcanic eruption to a soda bottle. When shaken, the bubbles separate from the liquid. Once you remove the cap, the liquid would squirt out. If you slowly uncap the bottle, the gases will slowly squirt as well. When you finally open the cap, the liquid will either stay or squirt a bit. It’s the presence of gas inside the magma that makes the volcano more explosive, said Solidum. 

By now, the magma at the surface or near the surface has degassed, according to the geologist. “Since February, when we had a lot of earthquakes, the gases were also escaping the Taal Volcano. That is why in some cases, there were large amounts of sulfuric dioxide gases coming out of the volcano, sometimes dispersed by winds to different areas. 

“In some cases, because of the moisture of the air, and the wind was not so strong, and the temperature was a little bit cold, the sulfur dioxide gases mixed with moisture and the cloud of sulfur dioxide became fog or smog. So it affected the surrounding areas of Taal Volcano.”

Flying rocks at a speed of over 60kmh – what could happen if Taal erupts 3
Taal Volcano emits steam as fisherfolk navigate Taal lake in Talisay, Batangas on June 30, 2021. Photo by Jonathan Cellona, ABS-CBN News

On how far ahead can PHIVOLCS predict a huge explosion

It’s hard to be certain when a volcano would produce a large explosion, said Solidum. The best that geologists can do is monitor the earthquake events and measure the gases. The latter can be quite difficult if there are large amounts of sulfur dioxide gases coming out, because it can be dangerous, especially when there’s rain. 

PHIVOLCS also uses an electronic tiltmeter used to measure subtle changes in the ground slope and shape of the volcano, and a global positioning system that allows geologists to observe what’s happening within the volcano. These would suggest the kind of volcanic activity expected and if the alert level needs to be increased. “If you talk about alert level 3, large, hazardous explosion can happen within weeks, if the trend would continue. If we raise it to 4, that kind of explosive activity can happen within days to hours,” said Solidum.


On Taal erupting with the same intensity as last year’s 

Although there are ongoing explosions, PHIVOLCS is not expecting a very large one compared to that of January 2020 —that is, if the present condition stays as is. If there is a new batch of magma rising from below and this carried lots of gases, the volcano’s eruptive activity could change—“from an explosive but not so strong, to a more explosive one.”

It could explode in the same manner it did in 2020, said Solidum. But the worst case scenario would be “horizontally moving clouds of acids and rocks at a speed of more than 60km per hour. This can travel even on water, reach the shoreline, and even further inland.”

The geologist mentioned that in the 1754 eruption, almost the entire coastal area of Taal and many towns were buried in 1 to 3 meters of volcanic ash. The account of how many died was not clear but the eruption led to the relocation of the center of Taal, Lipa, and Tanauan. Taal town is now in Balayan Bay, which is many kilometers away from the lake.

It is also possible Taal will just show fireworks, which was what happened in 1968 and 1969. The danger this entails would all depend on the amount of gas it releases and if there will be new magma coming from below. “We don’t see that yet. We just see shallow level magma, with less gas. It is still dangerous, but not so if compared to last year,” added the PHIVOLCS OIC.


On stopping a volcano from erupting

There’s actually nothing humans can do to prevent a volcanic eruption. What we can do, said Solidum, is avoid the wrath of the volcano. “Don’t go near it if it’s angry. You have to go further away.” 

He explained, however, that PHIVOLCS cannot advise towns and villages to evacuate each time a volcano threatens to erupt as this would disrupt lives and lead to severe economic losses. They have to strike a balance between development and the volcano’s hazard.

Generally, this dilemma could be prevented through appropriate land and lake use, and much easier to adopt with volcanoes that are conical. “You just run away from the crater,” he said. But it’s a different case with Taal Volcano because “it’s on an island, and that volcano can actually devastate areas around it, even across the water, and many of the towns around it.”

Solidum explained that the Taal Volcano sits on a bigger volcano called the Taal Caldera. “It’s like you are located in a bowl. So if you want to be safer from the volcano, you have to run away from it, climb the mountain, which is actually the crater rim of the bigger volcano, and go beyond it, so you’d be safer from Taal. This situation is a little different from our other volcanoes,” Solidum explained. 


What is a possible major hazard of the Taal Volcano eruption?

Taal has a big crater, and eruptions could occur on the side of the island. There are also cases where the explosion isn’t only vertical but also horizontal in trajectory. “That was the scenario we were worried about last year,” said Solidum. This year, there can be horizontal moving clouds that would cross the lake and reach further out. We call that bay surge. Those are the most dangerous hazards, not the lava flow,” he explained.