Around the planet, there are a group of several prominent volcanoes which are considered to
be the world's most active, as they are almost always continuously erupting in some shape
or form.
These include Kilauea in Hawaii, Mount Etna in Italy, and Mount Stromboli in Italy.
Yet, there is one seemingly missing volcano which is frequently omitted from this list,
despite being far more active.
The volcano in question is known as Mount Yasur, which has been continuously erupting
without a single pause in activity since 1774.
However, there is more to this figure.
This date of the eruption's apparent beginning was incorrectly attributed to when Captain
Cook visited the island.
In reality, Mount Yasur may have been continuously erupting for as much as 870 years straight,
marking it as the single longest continuous erupted in recorded history.
Today, it produces intermittent explosions every 1 to 3 minutes which eject bombs of
lava and on occasion generate small ash laden pyroclastic flows.
The Yasur stratovolcano can be found far east of Queensland, Australia within the island
of Tanna in Vanuatu.
The ash covered vent and flanks visible on satellite represent the general vicinity which
bombs of lava fall during continuous eruptive activity.
It may be difficult to tell at first, but underneath Yasur is an unusually massive magma
chamber.
Several kilometers beneath its edifice is 25 cubic kilometers of magma.
This is sufficient to produce a major caldera forming eruption which could devastate the
entire island.
And, on one occasion within the last 20,000 years, a caldera forming eruption did occur.
During this still yet to be dated young eruption, 2 cubic kilometers of volcanic rock was ejected,
and pyroclastic flows traveled up to 14 kilometers distant.
Then, an 8 by 4 kilometer wide section of the volcano collapsed downwards, forming the
caldera which is outlined on screen.
In the thousands of years since, magma has once again refilled much of what was emptied
during this major eruption, thus pushing the center of the caldera upwards in what is termed
a resurgent dome.
This uplift is among the fastest seen on the planet, as the large oval shaped dome along
with part of Port Resolution is uplifted 15 centimeters each year.
Faults associated with this long term uplift have provided for a path of least resistance,
allowing for the construction of two medium sized volcanic cones, Ombus and Yasur.
Ombus was the first to form, which through continuous explosive eruptions that occurred
for several hundred to several thousand years created a 190 meter or 623 foot tall cone.
After this cone stopped erupting, lava found a new path of least resistance to the northwest
around 870 years ago.
It then began an explosive sub-plinian eruption, creating a towering plume of ash which shot
more than 15 kilometers into the atmosphere.
After the volcanic intensity subsided, strombolian style eruptive activity dominated by the ejection
of bombs of lava and ash every 60 seconds continued.
This over time constructed a volcanic cone similar to the ongoing eruption of La Palma,
albeit at a slower rate.
On occasion, the viscous magma which erupted, which had a composition of basaltic trachyandesite,
would plug a section of the active vent.
A small amount of combustible gasses would then build underneath this plug, until finally
a more explosive vulcanian explosions occurs.
These explosions can be differentiated as not only do they eject bombs of lava but also
produce a thick ash laden column alongside small pyroclastic flows.
Since 1150 AD, this long term eruptive activity constructed the 361 meter or 1184 foot tall
Yasur volcanic cone.
On occasion, such as in 1920, long distance lava flows have emerged on the flanks of the
volcano, although such flows are infrequent.
Although this volcano can produce even larger eruptions, its main overall hazards relate
to the threat of bombs of lava and superheated gas associated with explosive eruptions, which
can travel up to 3 kilometers distant at a maximum.
Because it has been erupting for such a long time, it makes for the perfect destination
to visit as you are guaranteed to see this volcano in an active state.
Just remember to stay clear of its northern flank and summit area, and also keep an eye
on Yasur's alert level as this determines what areas of the volcano can be accessed.
I hope that you enjoyed this video.
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