When people think of geologic hazards in California, they tend to not think
about volcanoes. Yet, alongside earthquakes, volcanoes also pose a major threat in the state.
California has 9 active volcanoes which have erupted in the last 10,000 years, and an
additional 3 volcanoes are not currently active but could erupt in the future. This video will
focus on the 3 active volcanoes in the southern third of california. Subsequent videos will cover
the rest of the volcanoes in California, as I did not want to make this episode too long.
For this video, we are defining an active volcano as any volcano or volcanic field
which has erupted in the last 10,000 years. The first volcano we will cover is the Salton
Buttes volcano, which is the furthest south active volcano within the state of california. The Salton
Buttes volcano gets its name as it occurs within the Salton Sea. The Salton Sea volcano consists
of five lava domes which occur in a 7 kilometer long chain in an area which is slightly below
sea level. These lava domes formed within a region of California which is slowly tearing apart from
each other. Within the last 10,000 years, this volcano has erupted three times. Each time, an
eruption formed a rhyolite rich lava dome, which rose 30 to 40 meters above the surrounding terrain
in relatively small eruptions. The most recent of these eruptions occured at red hill, which erupted
in the year 210. The other two lava domes formed in the year 10 and 290 BC. The Eruption which
occured in the year 10 is of particular note as the eruption at this dome called Obsidian Butte
formed a large amount of the volcanic glass known as obsidian, which is still present today. If
you were to visit this volcano today, it would be quite obvious that it is still active. The
volcano has several so called mud volcanoes, such as the one shown on screen. Additionally, it also
has several warm vents which emit small amounts of volcanic gasses. If this volcano were to erupt
again, it could pose a threat to several nearby towns, the largest of which is westmoreland.
The second volcano we will cover is the golden trout volcanic field. This volcanic field has
been erupting at infrequent intervals over the last 750,000 years. What we are zooming into
is the most recent eruption of this volcano, from an area termed Groundhog Crater.
This area last erupted around 5500 BC (5550 +- 2500 yrs), although there is a wide margin
of error with this data. Like most eruptions from this volcanic field, it created a new cinder cone.
Cinder cones form from a combination of both explosive and effusive volcanic activity. In
these style of eruptions, lava essentially shoots straight up from a volcano, and a series of small
explosions deposit small amounts of ash around the volcano. This volcanic field is not likely
to erupt again in the next 5,000 years. The third volcano we will cover in this video
is known as the Ubehebe Craters, which lies within Death Valley national park and is relatively close
to the border of Nevada. The Ubehebe Craters are a series of 15 explosion craters called maars which
are associated with a fault system that runs across them. All of these craters formed from
explosive eruptions. The widest of these explosive eruptions formed a crater which is 800 meters wide
and 235 meters deep. The eruption which formed this crater is termed as a Phreatomagmatic
eruption. This style of eruption is similar to an explosive phreatic eruption caused by the flashing
of groundwater to steam, but it actually contains some lava. This volcano last erupted in 150 BC.
All three volcanoes in this field produce explosive eruptions, with some being larger
than others. With this being said, only one of these volcanoes poses a substantial future risk
to a nearby population center. The volcano in question is the salton buttes volcano, as 38,000
people live within 30 kilometers of this volcano. A future eruption could pose a risk to these
people in addition to air travel over southern california and the nearby geothermal power plants.
Although volcanic domes are built by non explosive eruptions of lava, they do on
occasion generate deadly pyroclastic flows. As a result of this hazard,
the salton buttes volcano was assigned a high risk designation from the US Geological survey.
The golden trout creek volcanic field was assigned a very low risk designation for several reasons.
Very few people live nearby, the volcano erupts very infrequently,
and the historical volcanic eruptions from this volcano were quite small.
The Ubehebe Craters were assigned a moderate risk designation by the US Geological survey.
Why? Although very few people live in the area of death valley, the eruptions from this
volcano are ALWAYS explosive in nature. I hope that you enjoyed this video! If
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