Geology, Homeschooling

Phreatomagmatic Eruption as Explained to Kids

In the previous post, I explained the mechanism that drove the phreatic eruption of Taal last January 12. Yesterday, PHIVOLCS announced that Taal is now at the stage of Phreatomagmatic or Hydrovolcanic activity.

What does that mean?

Screenshot of Dr. Encarnacion’s (a_geologist @ IG) sketch below illustrates what could be happening inside Taal. The magma has intruded the water table, thus, more steam is generated – scientifically, this is called FLASHING. What happens when you drop water on super heated oil? It creates a huge amount of steam mixed with oil droplets, doesn’t it? That’s what’s going on in Taal except the oil is magma – portions of magma are currently being blown out into the atmosphere along with water and rock fragments. If you have been collecting ash from day one (I know some of my geologist friends do), you will see a difference in the composition of the grains now compared to the ashfall of January 12-13. Look for volcanic glass – they look like ground up glass bottles, usually, amber in color. We Geologists fondly call them frozen magma.

Why has the steaming and ash fall slowed down? Well, the volcano has depressurized a bit during the eruption last Sunday. But that does not mean that the danger is over. Yesterday there were recorded 335 tremors in Tagaytay and vicinities and cracks/fissures as long as 3 kilometers were observed. These are indicators that magma are upwelling or rising – the rocks around are responding to bulging. The question really now is when will Taal blow off for the finale? We don’t know. She is one crafty prima donna.

If we are going to look at Taal’s history, she has been known to blow off anytime without warning. The current behavior of Taal is mirroring the infamous 1911 eruption event that killed around 1300 people.

So please, if you have friends still within the 14-kilometer danger zone of Taal, tell them to evacuate now. It’s not safe.

Phreatomagmatic eruption of Taal as illustrated by Dr. Encarnacion.
This is the latest bulletin from PHIVOLCS taken out of their official Facebook page just today describing that there are now 466 volcanic earthquakes recorded since January 12 – signifying continuous magmatic intrusion underneath Taal. The volcano remains under Alert Level 4.

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