Within Mexico are a number of highly explosive volcanoes.
The most notable recent large eruption originated from El Chichon in 1982, which buried a number
of towns in an 8 kilometer radius with 3 meters of ash.
Although this eruption was quite large, as it ejected 2 cubic kilometers of volcanic
rock, its eruption does not even compare to another recent eruption from a separate volcano.
130 kilometers west northwest of the city of Guadalajara, is a volcano known as Ceboruco,
which contains several young lava domes and two massive calderas.
It produced the largest volcanic eruption of the last 10,000 years in Mexico, which
was 5.5 times the size of the aforementioned eruption of El Chichon.
This catastrophic eruption occurred a mere 1100 years ago, and due to the recent eruptive
history of this volcano, it will erupt again.
Today, we know that this volcano is still active as its summit contains a number of
fumaroles which are actively emitting volcanic gasses.
This volcano began forming 370,000 years ago, when magma related to the offshore subduction
of the Rivera Plate underneath the North American plate reached the surface.
Although the magma was highly silica rich, with a composition of andesite, its initial
eruptions were not very explosive.
These initial eruptions built large gray colored lava domes, which had a jagged appearance
and did not travel very far from their initial vent.
Over a subsequent period of more than 250,000 years, dozens of large lava domes were constructed
on top of one another, which built a towering gray colored volcanic edifice with several
secondary peaks.
At the end of this phase of eruptive activity, Ceboruco had a height of 2,700 meters or 8,858
feet.
In other words, it was about 400 meters taller than it is today.
After a pause in eruptive activity, eruptions shifted away from the main edifice.
Between 100,000 and 2,000 years ago, a series of more than 30 satellite vents formed along
a northwest line of activity, which stretched for 40 kilometers.
These vents included a combination of andesitic cinder cones, which erupted in a mildly explosive
manner with bombs of lava and ash, and lava domes, which contained thick and very slow-moving
flows of material.
During this period of dormancy at the main edifice, the underlying magma chamber grew
more and more silica rich.
Andesite had changed to dacite which later changed to rhyolite.
Then, a small eruption occurred back at the main edifice, which produced a several kilometer
long lava flow of an unusual composition, called trachydacite.
This change in composition was a warning sign of a major eruption which would occur a mere
20 years later.
This major eruption began with the construction of another new lava dome at the summit of
Ceboruco.
Over the next several weeks, it grew larger and larger until finally gas was unable to
escape.
This caused an immense amount of pressure to build, until finally, a massive eruption
began on the surface.
As the gas found a path to escape, it ignited, generating a powerful explosion, leaving behind
a several kilometer wide crater.
As a plume of ash rose more than 40 kilometers into the atmosphere, pyroclastic flows raced
across the surrounding landscape, destroying all vegetation in a 15 kilometer radius.
As the newly formed crater was breached to the north, a significant portion of the pyroclastic
flow was directed to the north, where it traveled up to 25 kilometers distant.
Then, due to the large amount of material erupted, a 3.5 kilometer wide section of the
volcano collapsed by 200 meters, forming a large caldera.
In total, 11 cubic kilometers of volcanic rock had been ejected, meaning this eruption,
which occurred on 930 AD had a volcanic explosivity index as 6; the same as the 1991 eruption
of Mount Pinatubo.
In the aftermath of this eruption, several large lava domes were extruded onto the surface,
such as El Norte, whose thick black lava flows can be found on the entire northern half of
the volcano.
About 100 years later, another explosive eruption occurred, forming a 1.5 kilometer wide crater
in the center of the larger caldera.
Since then, successive lava domes have refilled much of the area which collapsed, but the
caldera walls are still visible.
Two of these eruptions occurred in 1542 and 1567.
The most recent eruption began in 1870 and produced a series of three dacite lava domes.
The smallest of the domes created by the eruption is only 130 meters wide, while the longest
lava flow just to its west traveled up to 7 kilometers away.
Due to the presence of active fumaroles around Ceboruco, it still has an active at depth
magma chamber.
This magma chamber could produce an eruption with only 1 to 2 weeks notice at any time,
with the odds of a new eruption each year being about 1 in 250.
Such a new eruption would be highly explosive, and create long distance pyroclastic flows
associated with lava dome collapse and lava dome destruction.
Thus, if this volcano was to ever erupt again, a 15 kilometer evacuation radius would be
needed.
I hope that you enjoyed this video.
If you would like to request a specific topic please leave a comment below.
Additionally, if you wish to support this channel, consider becoming a patron on patreon!