In 1991 the eruption of Mount Pinatubo shocked the world due to its horrific intensity, as
it caused the summit region of the formerly 1750 meter high peak on the island of Luzon
to collapse into a caldera with a floor at an elevation of only 900 meters.
This eruption was the largest to occur on the planet since 1912, which in addition to
creating a 40 kilometer high eruption plume, created valley filling pyroclastic flows which
coated the landscape up to a distance of 16 kilometers from its former summit.
While this catastrophic eruption is still well known, it might come as a surprise that
this was not the first caldera forming eruption to occur in historic time in the Philippines.
As, far to the south on the island of Mindanao a similar lake filled caldera can also be
found.
While few people are aware that this volcano exists, this near carbon copy of Mount Pinatubo
is today known as Mount Parker or Mount Melibengoy.
This volcano contains a 3 kilometer wide and nearly 400 meter deep caldera which formed
during a highly explosive eruption on January 4th, 1641.
Although Mount Parker has not erupted since, it is still considered active as it presumably
still contains an at depth magma chamber which supplies heated water to hot springs which
reach up to 55 degrees Celsius or 131 degrees Fahrenheit.
And, if you look closely around the volcano, you might even see outcrops of thick ash layers
several meters thick which originated from the 1641 eruption.
The Parker volcano can be found in the far southern Philippines on the island of Mindanao,
where it is 30 kilometers west of General Santos City.
Although the exact age of this volcano is unknown it is quite similar in appearance
to Mount Pinatubo which also displays significant amounts of erosion around its complex.
Thus we can assume that Parker is of a similar age, perhaps slightly younger, so I suggest
it began erupting around 500,000 years ago.
Initial eruptive activity likely began 6 kilometers northeast of the modern caldera lake, where
a volume of basaltic andesite magma intruded into the crust before explosively erupting
onto the surface.
These early eruptions were moderately explosive, and alongside generating occasional fountains
of lava began building a gray colored stratocone with a red coloration on and near its summit
created by ejected scoria.
By 30,000 years ago, magma has once again become more silica rich after prolonged leaching
of silica into the magma chamber from the surrounding crustal rock, causing its composition
to change from andesite to dacite.
And this is when it appears the style of Mount Parker changed; going from a mildly explosive
volcano with frequent eruptions to a highly explosive volcano with infrequent eruptions.
In a manner of speaking, Mount Parker became like Mount Pinatubo, except its eruptions
were generally 3 times less voluminous in terms of ejected tephra.
The first of 4 powerful volcanic eruptions which would happen occurred 28,000 years ago,
which in my opinion likely ejected more than a cubic kilometer of volcanic rock and devastated
the landscape in a 10 kilometer radius.
For the next 24,000 years, no powerful eruptions occurred and the volcano most likely lied
dormant.
However, I want to note that I am not confident that the current known eruptive history of
this volcano is complete.
As, in 1992, 1993, and 2021 Mount Pinatubo produced minor explosive eruptions which were
so insignificant that if people had not witnessed them they likely would have been lost in the
geologic record.
The same thing is probably true with Mount Parker which also likely had a few infrequent
small explosive eruptions after or between each major eruption.
The next major eruption occurred in 1920 BCE, creating a tall ash column which partially
collapsed due to its own weight, creating pyroclastic flows which were recorded traveling
up to a distance of at least 7 kilometers away.
Another similarly sized eruption followed in 1380 BCE.
The most recent eruption began during the last week of December of 1640 which initially
produced numerous vulcanian explosions and tall fountains of lava.
This formed a plug which prevented a large amount of gas from escaping, which eventually
built up in pressure and exploded in a powerful eruption.
As a plume of ash shot high into the atmosphere, powerful pyroclastic flows and lahars destroyed
vast stretches of landscape up to a distance of 20 kilometers away from Parker's former
summit.
Then, due to the large amount of erupted material, which I estimate to be around 8 cubic kilometers,
the underlying magma chamber now had empty space.
This caused overlying ground to collapse downwards and form its modern caldera.
Thanks for watching!
If you would like to request a specific topic, please leave a comment below.
Additionally, I would like to thank Alan Smithee for increasing their patron tier on this channel's
patreon page!