The state of Oregon contains about a dozen active volcanoes. These active volcanoes
include Mount Bachelor and Mount Jefferson. However, not all of the volcanoes within the
state are tall stratovolcanoes. One of these lesser known volcanic fields is a very popular
fishing spot for rainbow trout. What I am referring to is the Davis Lake volcanic field.
This video will discuss this active volcano, and mention what its future hazards are.
The davis lake volcanic field can be found in the west central portion of Oregon.
Specifically, it is 41 miles north of Crater Lake, and 16 miles west of the town of La Pine.
Before I begin, I want to note something. Of the more than 50 volcanoes I have covered in my
series so far, I have never seen such a poorly documented active volcano. As a result, a good
portion of this video will be using reasonable guesses given my geologic knowledge of the area.
When I am using a known fact, I will color code text red. When I am using my own hypothesis,
I will color code text golden. The Davis Lake volcanic field
began forming around 100,000 years ago, when a series of eruptions created six shield volcanoes.
These shield volcanoes formed over a timespan of about 15,000 years,
as low viscosity basalt lava erupted from a central vent and quickly flowed downhill.
As a result of the lava's fast movement speed, it formed several volcanoes with gentle slopes
of about less than ten degrees. The largest of these shield volcanoes is Davis Mountain,
which has a base about 6 miles wide. This mountain is about 2200 feet tall,
and is very similar to the much younger active Belknap Crater volcano to the north.
This volcanic field then became dormant for about 50,000 years. During this time, the existing
volcanoes were eroded by snow and ice from the last glacial period to form a smoother surface.
Then, in 2790 BC, steam and ash began rising from a series which formed in a northward direction.
Soon, lava began erupting out of four vents, and small explosions caused ash to fall anywhere
within a few miles. The cinders from four simultaneous eruptions largely built up near
the base of the erupting vents, forming cinder cones. From these cones and fissures emerged a
type of slow moving blocky lava. This lava moved downhill at a rate of about 30 feet each day. As
the eruption continued, cooled lava formed rugged features due to their high viscosity.
The northernmost of the three lava flows dammed one of the area's rivers which formed Davis Lake.
Then, about a year after the eruption began, it ended. The vast majority of lava traveled
no further than a mile from an eruptive vent, with the furthest away a lava flow reached being 9,000
feet. Since this eruption, no additional activity has taken place in this volcanic field.
So, what hazards does this volcanic field pose in the future?
In their most recent volcano hazard assessment, the US Geological Survey designated the davis lake
volcanic field as their lowest threat category, called "very low threat". The reasoning for this
low risk designation is primarily due to its infrequent eruptive history. This volcanic field
erupts in bursts of activity which take place every 50,000 years. When these eruptions occur,
they pose little hazard to anything outside of the immediate vicinity of an erupting vent.
The radius of potential danger for this style of eruptions is about 3 miles, which is very small
compared to other volcanoes in Oregon. If a future eruption was to occur, it would likely take place
on a similar northward trending fissure. This hypothetical eruption would once again erupt
andesite lava which would move at a very slow speed, which represents the main future hazard.
However, I do not expect an eruption from this volcanic field
anytime soon. Until the next eruption tens of thousands of years in the future, enjoy the
scenery and fishing which the area offers. I hope that you enjoyed this video. If
you would like to request a specific topic, please leave a comment below!