California is host to a number of large active volcanoes such as Mount Shasta and Lassen
Peak.
However, towards the southeastern part of the state, in the Mojave Desert, there are
a group of several young lava fields which few are aware of.
One of these lava fields is located 15 miles southeast of the town of Baker, which produced
an eruption within the last 12,000 years.
The volcano I am referring to is called the Cima Lava Field, which could be classified
as an active volcano.
This video will discuss this volcano, and mention what its future hazards are.
The Cima Lava Field is a volcanic field within California which encompasses 52 different
volcanic cones over an area of approximately 230 square miles or 600 square kilometers.
These vents are all cinder cones, which are formed by intermittent ash explosions which
fall close to the erupting vent.
The reason why this volcano exists is due to stretching of the crust in this section
of southeastern California.
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 first eruption from this volcanic field occurred 7.6 million years ago, when magma
at depth erupted onto the surface in the northern part of the volcanic field.
While a series of several cinder cones were constructed, lava flows began traveling westwards
since the ground sloped gently in that direction.
During a several month long eruption, these lava flows travelled up to 5.5 miles away,
depositing a black volcanic rock.
Since these lava flows spread out over a large area, they formed a raised rim.
Eventually, some of the surrounding rock was eroded away while the hardened basalt remained
since it was more resistant to erosion.
As a result, a series of volcanic mesas were constructed.
Between 6.4 and 5.2 million years ago, this volcanic field became dormant.
Then, 5.1 million years ago, it erupted once again at a new location 7 miles to the south.
Once again, a series of eruptions formed a group of cinder cones, but this time they
occurred along a hidden northward trending fissure in the crust.
As a result, over the subsequent 1.5 million years, a vast lava plateau was constructed
with a rather uniform rim to the west.
From 3.5 to 1.2 million years ago, this volcanic field became dormant once again.
When lava again erupted onto the surface 1.1 million years ago, it occurred to the south
of the two previous eruptive centers.
Since eruptive activity has resumed, at least 30 different cinder cones have been formed.
These cinder cones widely varied in size depending on how long the eruptions which formed them
lasted.
The largest of the recent cinder cones, which in this case is called Cone G, is 3200 feet
wide and 650 feet tall.
One recent vent formed 27,000 years ago, as magma rose towards the surface.
As this magma interacted with a volume of groundwater, it caused it to flash to steam
and subsequently explode.
This explosion carved out a 2700 foot wide crater in an already existing cinder cone,
thus destroying its top.
Afterwards, a small volume of lava erupted into this crater, forming a small volcanic
cone within an older cinder cone.
The two most recent eruptions from this volcanic field occurred at an adjacent cinder cone
to the southwest.
The first eruption 21,000 years ago formed a 300 foot tall cinder cone.
The most recent eruption occurred 11,500 years ago.
This eruption blasted out a portion of this cinder cone to the west, from which a small
lava flow emerged.
This lava flow traveled 8000 feet in the span of about 2 weeks before it stopped.
Since then, no additional eruptions have occurred.
If this volcanic field was to erupt again, it would pose only one major hazard due to
its relatively small eruptions.
During a future eruption, a lava flow would erupt from a new vent, which over time would
build a cinder cone.
This lava flow could technically travel up to 6 miles away, thus burying nearby roads
and starting wildfires.
Luckily, no major cities are within direct reach of these lava flows.
The next eruption from this volcanic complex will almost certainly occur in the far southern
region, which is where other recent eruptions have occurred.
Using the US Geological Survey method of rating volcanoes, Cima lava field would be classified
as a very low threat volcano.
Overall, the odds of the Cima Lava Field producing another eruption are about 1 in 12,500 each
year.
I hope that you enjoyed this video!
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