Canada contains 21 active volcanoes.
Of these, the vast majority are located within British Columbia, such as the Tseax Cone,
which last erupted in 1700.
However, in the northern part of the province there are much larger volcanoes which tower
more than 1000 meters above the surrounding landscape.
One of these volcanoes last erupted in 950 AD, and is one of the most active volcanoes
in the entire country.
The volcano I am referring to is called Mount Edziza, which will erupt again in the future.
This video will discuss this volcano, and mention what its future hazards are.
Mount Edziza is located in an isolated portion of northwest British Columbia.
Specifically, it is 37 kilometers west of the small community of Tatogga.
The reason why Mount Edziza is elongated towards the north and south relates to how this volcano
formed.
In this section of British Columbia, tectonic forces are slowly stretching the crust to
the east and west.
This stretching of the crust creates a series of cracks, which then allows magma to travel
upwards and erupt onto the surface.
As such, Mount Edziza is a stratovolcano associated with a long fissure of magma.
Mount Edziza began forming 1.1 million years ago, when magma from this fissure erupted
onto the surface.
This initial period of activity saw the construction of the north central area of the volcanic
complex.
Numerous highly explosive eruptions created overlapping layers of viscous lava which formed
lava domes.
These lava domes contained a gray rock type called trachyte.
By 900,000 years ago, the modern summit of Edziza had been constructed.
Eventually, volcanic activity shifted to the northeast of Edziza to a series of several
dozen vents and cinder cones.
These vents erupted simultaneously, and produced thick basaltic lava flows which cooled as
a black color.
Due to the large amount of lava these vents erupted, the center of Mount Edziza collapsed
downwards, forming a 2700 meter wide caldera.
Today, this caldera is overlaid be a thick glacier.
During the next several tens of thousands of years, large lava lakes repeatedly formed
in the caldera of Mount Edziza.
These lava lakes intermittently overflowed to the east, thus traveling down a ravine.
Since then, the vast majority of eruptions at Edziza have not occurred at its summit.
Rather, they have intermittently occurred in pulses at smaller satellite vents called
cinder cones.
In the last 100,000 years at least 30 such eruptions have occurred.
One of these eruptions occurred in 6250 BC, and was quite explosive.
A small volume of magma rose to the surface, causing some ice to rapidly flash to steam
and explode.
This explosion created a 260 meter wide crater on the northwest of the volcanic complex,
and generated a short distance pyroclastic flow.
An even larger eruption occurred in 750 BC, which constructed a 100 meter tall and 500
meter wide cinder cone called the Eve cone.
This eruption also produced a vast lava flow, which traveled to the north, reaching up to
12 kilometers away from the erupting vent.
A third recent eruption took place on the north of the volcanic complex, and was an
order of magnitude more explosive.
It created an even larger cinder cone, and covered a vast area with red scoria and black
basalt.
The most recent eruption occurred in 950 AD to the southwest of the main peak at the Tennena
cinder cone.
Today, we know that Edziza is still active because the area surrounding this volcano
contains several active hot springs, one of which regularly outputs water at a hot 46
degrees Celsius.
This warm water hints at a rather shallow body of magma underneath the volcano.
If this volcano was to erupt again, it could endanger a number of towns to the north.
Although Mount Edziza has generated small pyroclastic flows and long distance lava flows,
none of these have traveled beyond 20 kilometers of its main peak.
The main threat from Edziza is lahars.
Whenever a large eruption occurs, volumes of ash get deposited.
This ash is then largely washed away during the next rainstorm.
As a result, rivers experience a phenomena similar to a flash flood, where a towering
wall of water, ash, and cooled lava advances.
This phenomena is called a lahar, and could effect a number of low lying areas at towns
to the north.
Using the US Geological Survey method of rating volcanoes, Edziza would be classified as a
moderate threat volcano.
The odds of it erupting each year are about 1 in 2000.
I hope that you enjoyed this video!
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