The Taal volcano is one of the most well known volcanoes in all of the Philippines, due to
its frequent and large eruptions.
However, just to the east of Taal is a completely different but active volcanic complex.
As we zoom in, you can see a number of circular lakes in the vicinity, including two adjacent
to San Pablo City.
These lakes are in fact volcanic explosion craters termed maars.
They are part of a larger volcanic complex called the Laguna Volcanic Field.
One of these eruptions was witnessed by native peoples, as it occurred in 1350 AD.
Today, the area is one of the most densely populated volcanic fields on the planet, as
more than 1.3 million people live within 5 kilometers of one of its vents.
This video will discuss this volcano, and mention what its future hazards are.
The Laguna Volcanic Field contains at least 28 separate vents spread out over an area
of approximately 330 square kilometers.
The majority of these vents align with three east northeast trending faults, which act
as regional weak points, allowing magma to travel up through them and erupt onto the
surface.
This volcanic complex contains a wide variety of vents which include a stratovolcano, maars,
cinder cones, and lava domes.
The Laguna volcanic field began forming 500,000 years ago, when a volume of magma erupted
onto the surface in the northwest edge of the complex.
Initially, the magma erupted in a highly explosive manner, as it interacted with the abundant
groundwater in the vicinity.
After this phase of activity subsided, a series of slightly less explosive eruptions began,
which deposited alternating layers of lava and ash, thus slowly building a stratovolcano
called Maquiling.
Many of its eruptions were unusually energetic for a stratovolcano, as it erupted lavas with
high silica content such as dacite and rhyolite.
By 350,000 years ago, this volcano stood at 1090 meters tall.
Although this stratovolcano is today considered to be extinct, many hot springs can still
be found on its northern flank.
After this volcano stopped erupting, the entire volcanic field became dormant for 100,000
years.
Then, beginning 250,000 years ago, a series of eruptions occurred along a regional fault
in the crust.
As lava once again erupted onto the surface, it began to form a series of lava domes due
to its high viscosity.
While these lava domes continued to grow in size, parts of them would intermittently collapse,
generating a series of pyroclastic flows.
By the time this eruptive series had ended, a complex of a half dozen lava domes had been
constructed.
The next phase of activity saw the construction of several cinder cones, which produced intermittent
explosions associated with ashfall and small lava flows.
Today, these cinder cones can be easily spotted in the landscape due to their medium sized
profile and rounded summit crater.
The next series of eruptions formed a chain of maar explosion craters.
These explosions did not eject any lava, but were still quite energetic.
As an example, the smallest maar in this field is 387 meters wide and 20 meters deep.
These maar explosions occurred about once every 15,000 years.
The older of the maars are covered with grass and vegetation while the younger maars are
filled with crater lakes.
The most recent maar to form originated in 1350.
That year, a volume of magma rose towards the surface within this volcanic complex.
This magma interacted with regional groundwater, causing it to flash to steam.
Eventually, the pressure became too great, and the ground exploded upwards in a massive
eruption.
As a series of pyroclastic flows raced across the landscape, a tall ash plume rose into
the sky.
Once the ash cleared, what remained was a 1200 meter wide and 52 meter deep explosion
crater which is now filled with Sampoc Lake.
When this volcanic complex does erupt again, its main threat will depend on its eruptive
style.
In all likelihood, the next eruption will produce another maar explosion crater.
Such an eruption would create a series of pyroclastic flows and eject boulders of rock
at ballistic speeds, each of which could travel up to 8 kilometers away.
However, the next eruption could also produce a cinder cone or lava dome.
The main threat from these eruptions would be slow moving lava flows, which could travel
up to 3 kilometers from the erupting vent.
Using the US Geological Survey method of rating volcanoes, the Laguna Volcanic Field would
be classified as a very high threat volcano.
I hope that you enjoyed this video.
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