On July 1st 2021, the first eruption at the Taal volcano in the Philippines in 18 months
occurred.
This large phreatic explosion occurred due to the interaction of rising magma with groundwater,
which caused the water to flash to steam and explode.
Since then, at least 20 similar explosions have occurred, of which the vast majority
were an order of magnitude smaller than witnessed on July 1st.
Since the most recent explosion occurred only yesterday, the current eruptive sequence at
Taal is from over.
This video will discuss what is expected to occur in the next few weeks, and summarize
the eruption so far.
Before I begin, I must remind people to not travel to the volcanic island for any reason,
or to any point within the currently designated 7 kilometer radius exclusion zone.
The eruption which began on July 1st was preceded by a strong swarm of earthquakes which had
been ongoing for many months, since at least April 8th.
These earthquakes were caused by the movement of magma beneath the volcano.
The unusually large number of recorded earthquakes indicates and associated large body of magma
within the subsurface.
As this magma got shallower and shallower, it began to heat the crater lake on the volcanic
island to blistering temperatures of over 72 degrees Celsius.
Additionally, from this crater lake emerged a large volume of sulfur dioxide gas, which
escaped from shallow magma.
On at least 21 different occasions, some lava emerged into the bottom of the lake through
a vent, creating a volcanic explosion and associated series of pyroclastic flows.
While these phreatomagmatic explosions have intermittently occurred in bursts of activity,
the levels of emitted sulfur dioxide have fluctuated over a wide range of levels which
are still considered to be quite high.
As an example, on July 4th, the highest amount of this gas ever recorded at the volcano was
documented, indicating a larger quantity of shallow magma than in any other recent eruption.
For some additional context, during the January 2020 eruption of Taal, sulfur dioxide levels
never rose above 4400 tons per day, which is comparable to the amount of gas vented
yesterday.
Even if Taal does not prodcue any more eruptions, the current exclusion is warranted due to
the dangerous concentrations of this gas.
Sulfur dioxide is heavier than air, so it pools in low points.
Only 2 parts per million of this gas is needed over long durations to be considered unhealthy.
At 100 parts per million or higher, this is immediately dangerous to human health.
Numerous areas around the volcano currently contain the latter of these two concentrations.
Symptoms of overexposure to this gas include the smell of burnt matches, irritation to
the eyes, nose, and throat, and trouble breathing.
If you experience any of these symptoms, please travel further away from the volcano.
With this being said, we are not truly sure what will happen next as Taal, as the volcano
has not behaved like would be expected from previous eruptions.
The long term model suggests that a large explosive eruption will occur while the short
term model says that small explosions will continue before eventually petering out.
I am still leaning towards the long term model, as it would be logical for a large amount
of magma to cause a big eruption.
Such a large eruption would likely be preceded by an increased type of earthquake called
a volcanic tremor along with the evaporation of the crater lake.
Another potential warning sign would be a series of ever increasingly shallow earthquakes,
hinting at the movement of a new batch of magma towards the surface.
If it reached the surface, a highly explosive eruption with large pyroclastic flows would
be guaranteed.
Even if this eruption was to end tomorrow, I need to note that Taal has entered a new
period of activity.
Taal seems to produce sequences of eruptions in a relatively short timespan before becoming
dormant for a period of several decades (typically 50 years).
Examples include: 1873-1878, 1903-1911, 1965-1977, and 2020-present.
Thus, more eruptions will occur from Taal in the next decade.
Thanks for watching.
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