Utah is a state known for its beautiful scenery, national parks, and unique sandstone formations.
It is not known for its volcanoes.
However, the state of Utah has several volcanoes within its boundaries.
One of these volcanoes produced an eruption quite recently, only 730 years ago.
The volcano I am referring to is called Black Rock Desert, which is also responsible for
the best topaz crystals found within the state.
This video will discuss this volcano, and mention what its future hazards are.
The Black Rock Desert Volcanic Field can be found in west central Utah, where the site
of its most recent eruption is only 9 miles west of the town of Fillmore.
As we zoom in, you will see a dark black patch of ground which appears to be a burn scar
from a recent wildfire.
However, this is no burn scar, but rather a black lava flow from a large eruption in
1290 AD.
The Black Rock Desert volcanic field contains dozens of vents spread out over an area of
2700 square miles in western Utah.
The reason why this volcano exists is due to the thinning of the crust in the region.
The western section of Utah is slowly being stretched apart, allowing magma to move through
a series of faults and erupt onto the surface.
The Black rock desert volcanic field began forming 6.1 million years ago, when highly
explosive magma erupted onto the surface.
The lava which erupted had a composition of rhyolite, which contained very high concentrations
of silica.
As a result, the lava did not move very quickly, so large volumes of gas remained trapped in
the lava, leading to a series of spectacular explosions throughout the course of the eruption.
By the time the eruption had ended, a tall lava dome complex called Topaz Mountain had
been created.
This mountain is filled with numerous transparent gem grade topaz crystals, hence the name.
Over the next several million years, eruptions expanded to different areas of the overall
volcanic field.
One series of eruptions 900,000 years ago from a vent called Crater Bench covered an
area of 50 square miles with a dark black layer of basaltic lava.
Since about 400,000 years ago, eruptions have largely become centered to the west of the
towns of Holden and Fillmore.
One notable eruption 400,000 years ago created a 120 foot tall obsidian covered lava dome
called White Mountain.
Another notable eruption occurred 16,000 years ago 15 miles to the west of Holden.
There, a large volume of magma rose towards the surface.
However, at the time, this section of Utah was covered with a large lakebed.
The heat from the magma eventually caused some of the lake water to flash to steam which
eventually generated a large explosion.
After the crater formed by this explosion was filled in once again by water, the process
repeated itself several times.
By the time this eruptive series had ended, a 1000 foot tall and mile wide tuff cone stood
in its place.
The main 3100 foot wide explosion crater of this feature, called Pavant Butte, is still
visible today.
2,000 years later, a similar tuff cone formed to the south called Tabernacle Hill.
By the time of the formation of this vent, a large series of hot springs had become present
nearby due to the presence of a shallow magma chamber.
Today, these hot springs are still active, hinting at the potential for future volcanic
activity.
The most recent eruption occurred in 1290 AD and began with a large explosion.
After the dust from this explosion cleared, a lava fountain towered several hundred feet
into the sky.
Then, intermittent explosions of ash began, leading to the creation of a 250 foot tall
cinder cone.
From this cinder cone and a network of nearby lava tubes emerged a vast volume of lava,
which slowly crept over the surrounding landscape.
By the time the eruption had ended, 14 square miles west of the town of Fallon had been
covered by fresh layer of lava.
Although no eruptions have occurred since then, we know that this volcanic field is
still active.
In 2018 and again in 2019, a series of shallow earthquakes hit the region.
These earthquakes were later determined to have been produced by the movement of magma
in the crust in what is termed a magmatic swarm.
The location of these earthquakes is shown on screen, and their vicinity represents the
best candidate for the site of a future eruption.
Speaking of future eruptions, an eruption occurs about once every 8,000 years in this
volcanic field.
Although the next eruption is most likely to form a cinder cone, it could also be highly
explosive and create another lava dome or tuff cone.
Regardless, the next eruption will likely have an explosive component to it, requiring
the evacuation of people in a 10 mile radius.
As a result of these hazards, the US Geological Survey designated Black Rock Desert as a moderate
threat volcano.
I hope that you enjoyed this video!
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