Several thousand years ago, a large volcanic eruption began in western Nevada.
It was so energetic that it caused a plume of ash to shoot more than 26,000 feet or 8
kilometers into the atmosphere.
Simultaneously, pyroclastic flows raced across the landscape, burying everything in a vast
area in superheated rock.
These pyroclastic flows traveled at least 1.5 miles before coming to a stop.
For the next several hours, powerful explosions continued at the source vent, carving a larger
and larger volcanic crater.
By the time the eruption had ended, what remained was a series of two large complex craters.
The first and larger crater measured 1.5 miles long and 3/4 of a mile wide.
The other measured 1300 feet long and 1100 feet wide.
What had just occurred was a maar forming explosive eruption of the Soda Lakes volcano,
likely registering as either a 3 or possibly even a 4 on the volcanic explosivity index.
Today, this volcanic complex is still geothermally active and powers a local geothermal power
plant.
And, more than 10,000 people now live within a 10 mile radius of this volcano which could
all be theoretically placed at risk if it was to ever erupt again.
The Soda Lakes volcano is located 6 and a quarter miles west-northwest of the city of
Fallon within Nevada's Churchill County.
Unlike many other volcanoes within the United States, its main feature is not a several
thousand foot tall mountain, obvious group of lava flows, or even a recognizable cinder
cone which are fairly common across the western United States.
Instead, the main feature of the Soda Lakes volcano consists of two explosion craters
referred to as maars.
However, this complex does in fact contain 4 volcanic cones; three tuff cones are located
6 to 10 miles north of the maars and a highly eroded cinder cone known as Rattlesnake Hill
just northeast of the city of Fallon.
With the exception of Rattlesnake Hill, you might note that the two maars, three tuff
cones and the active geothermal field are located along a north-northeastern trend.
And, if you zoom out further, you will note other mountain ranges which also have this
same orientation.
This same orientation is not merely a coincidence, but rather exists in almost the entirety of
the State of Nevada being part of what is known as the basin and range province.
Here, the crust is slowly spreading apart to the east and west, creating large swaths
of terrain which largely look the same.
This extension creates a series of large fault lines in the crust, creating uplifted patches
of land known as horsts and subsided patches of ground known as grabens.
Over millions of years, this process created large mountain ranges and valleys.
Upwelling mantle material then used these faults as a path of least resistance, creating
magmatic intrusions some of which eventually erupted onto the surface, forming scattered
volcanic fields.
Although there are no obvious lava flows at the two Soda Lake maars, from satellite you
can see due to the presence of darker colored ground where thick ash fell during the eruption,
which occurred less than 10,000 years ago.
And, if you walk around the Soda Lakes you might be even able to see small bombs of lava
of a basaltic composition.
Although it is uncertain when exactly this explosive eruption occurred, the U.S. Geological
Survey suggests that it occurred sometime in the last 6,000 years.
One source even suggested the eruption is less than 1,500 years old, but this is less
certain.
As for the other vents, Rattlesnake Hill is 1 million years old while the three tuff cones
referred to as the Hogback Cones are anywhere between 10,500 and 18,000 years old, as noted
in a thesis by E. Anderson.
This means that the Soda Lakes complex might have erupted not once but twice since the
end of the last ice age, aka 11,650 years ago.
Although it does not have the typical appearance of a volcano, the extent ash and pyroclastic
flows traveled during the eruptions is quite visible from satellite.
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