Few people who live in Nevada are aware that the state contains several potentially active
volcanoes.
One of these volcanoes, called Soda Lake, produced two large eruptions within the last
3,000 years.
However, this is not the only volcano in the state which could erupt again.
140 miles north-northwest of Las Vegas is a much larger volcanic complex called the
Lunar Crater volcanic field.
The most famous of these vents is the namesake of the field, Lunar Crater, which represents
a 3,000 foot wide and 300 foot deep volcanic explosion crater.
This video covers the recent eruptions from this volcano, and states the general hazard
it could pose in the future.
The reason why this volcanic field exists is due to stretching of the crust throughout
Nevada.
This stretching has created thin zones in the crust which allows magma to travel upwards
and erupt onto the surface.
Since this magma originated directly from the mantle, it largely erupted as a dark black
volcanic rock called basalt.
The Lunar Crater volcanic field began forming 6 million years ago, as magma first reached
the surface just north of what is now US Route 375.
This first eruption began with a series of small explosions and the creation of several
lava fountains.
Over the duration of this eruption, a 400 foot tall cinder cone was built out of basaltic
lava.
Over the next 900,000 years, 66 other vents formed through a similar eruptive series.
However, a small number of vents erupted a much more viscous type of lava called trachyte.
Instead of forming cinder cones, this rock type formed lava domes, and represented far
more explosive eruptions.
Then, 5.1 million years ago, this volcanic field went extinct for 400,000 years.
4.7 million years ago, a second phase of volcanic eruptions began, but this time occurred less
frequently and further north.
During the next 1.7 million years, dozens of eruptions built additional cinder cones.
From 3 million years ago to 1.1 million years ago, this volcanic field became dormant once
again.
When the Lunar Crater field erupted once again, the eruption occurred 20 miles to the north-northeast,
representing the slow northward trending movement of this volcanic field.
In the last 1 million years, eruptions have become more frequent compared to older volcanic
fields while also being confined to a narrower and narrower area as they continued northwards.
For example, at the northern edge of the field, 30 eruptions occurred in a narrow 2.5 mile
wide space.
As cinder cone forming eruptions began to essentially pile on top of one another, far
more explosive eruptions became possible.
If a new intrusion of magma reached the surface, it would get blocked by large amounts of hard
volcanic rock.
As a result, pressure and heat would build, eventually causing nearby groundwater to flash
to steam.
This steam would then greatly expand in volume, and eventually generate a large explosion
via a phreatic eruption.
The explosion craters generated in these eruptions are called maars.
On the smaller end, you have the 2000 foot long, 1800 foot wide, and 200 foot deep crater
called the easy chair maar.
On the larger end of these explosions, you have the 3000 foot wide and 300 foot deep
Lunar crater maar, which formed almost instantaneously in a massive explosive eruption 131,000 years
ago.
This eruption would have been classified on the volcanic explosivity index as a 4.
The most recent eruption in this volcanic field occurred 38,000 years ago, which created
a 500 foot tall cinder cone.
During the eruption which formed this cinder cone, an explosion caused the western side
to collapse, leading to lava primarily flowing in that direction.
This lava traveled up to 2.5 miles from the erupting vent called Marcath Cone.
Since then, no additional eruptions have occurred.
Today, the Lunar Crater volcanic field is often used as a training ground for astronauts
and a testing ground for Mars rovers.
Although the overall volcanic field is dormant, it will erupt again.
Based on the rate of eruptions in the most recent period of activity, the odds of a future
eruption are about 1 in 17,000 each year.
A future eruption would most likely form a new cinder cone, but could also surprise us
with a new maar crater forming eruption.
Luckily, due to the remoteness of this volcanic complex, the only at risk area which could
have people at the time of its next eruption would be US Route 6.
I hope that you enjoyed this video!
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