As of January 16th, 2022, there are 50 volcanoes which are actively erupting.
These include volcanoes such as Karymsky in Russia, which is a prominent and highly active
stratovolcano constructed inside of a large caldera which formed 7700 years ago.
It also includes Kilauea in the Hawaiian island chain, which has been near continuously erupting
for the last 3.5 months.
With this being said, here are a few of this week's major volcano related news stories.
In Hawaii, the Kilauea volcano in the last several weeks has been having intermittent
cycles of on/off activity characterized by tall lava fountains followed by a brief pause
in activity.
Meanwhile in India, the nation's only volcano to erupt in historic times known as Barren
Island produced a new volcanic eruption.
And now, for this week's top story.
In the nation of Tonga, a surprise second new explosive eruption of the year began at
the Hunga Tonga Hunga Ha'apai volcano.
This volcano in Tonga had previously erupted from December 20th of 2021 to January 1st
of 2022.
Through intermittent white and black plumes of water vapor and ash, the island expanded
in size by 72%.
However, unknown to many at the time, some of the newly created land was located in a
precarious position and was structurally unstable.
This land was located over a sheer cliff representing Hunga Tonga's northern caldera rim.
Thus, when the volcano reactivated on January 14th, it generated a small tsunami as an estimated
50 million cubic meters of rock slid towards the ocean floor.
This tsunami was only 30 centimeters or 12 inches in height but was a sign of an even
worse event to come.
A day later, on January 15th at 4:28 pm local time, a far larger landslide occurred.
As half of a cubic kilometer of volcanic rock slid into the ocean, a towering tsunami was
generated, which hit the islands of Tonga a mere 15 minutes later with the maximum observed
wave height being 2.5 meters or 8 feet.
As the energetic tsunami wave seemingly refused to dissipate, it went on to strike the coasts
of New Zealand, Australia, and Hawaii.
After tsunami advisories were issued for the US West Coast, the tsunami went on to hit
that region alongside Alaska and western Canada.
What had just occurred may have been the largest volcanic eruption of the last decade.
I would assign the eruption a preliminary rating on the volcanic explosivity index of
a 4.
The loud boom associated with the landslide and magma interacting with seawater produced
one of the loudest sounds ever heard.
This sound reached more than 9200 kilometers or 5700 miles away and was heard in the towns
of Kenai and Homer in Alaska.
In Hawaii, Kilauea's several month-long eruption is continuing, which is completely confined
to its summit caldera.
This lava has since overflowed onto the first of two caldera collapse blocks created by
its 2018 eruption.
However, as of late, eruptive activity has changed.
Instead of being defined by continuous low levels of eruptive activity, there is instead
a prominent on and off cycle.
Beginning on December 4th, Kilauea began a series of cycles dominated by 2 to 4 days
of lava effusion in the lava lake followed by a 1 to 3 day pause in activity.
During the onset of each new phase, large lava fountains are generated, and the rate
of lava effusion is at its highest.
The rate of lava output subsequently decreases until it reaches zero, causing a pause in
activity.
This is marked by a pattern of uplift and subsidence representing the intrusion or absence
of new magma in Kilauea's shallow magma chamber.
My interpretation of these cycles is that this individual eruption of Kilauea is nearing
its end and may only last for another month.
Like in the case of Geldingadalir in Iceland, the first phase of the eruption produced continuous
lava effusion while the second phase produced intermittent lava output as the overall supply
of fresh magma decreased.
In the context of Kilauea, it means that the potential rate at which lava can be erupted
onto the surface is higher than the continuous supply of magma to it.
Thus, the lava builds during pauses in activity, reaches a threshold, and erupts once again.
When the shallow magma chamber is sufficiently drained, the eruption pauses.
In addition to the eruption of Hunga Tonga, this week produced a second new volcanic eruption
at India's active Barren Island volcano.
This island represents the emergent summit of a 1.8 million year old stratovolcano and
contains a 2 kilometer wide caldera in its center.
On January 9th, a new eruption began at the volcano, producing a small plume of ash which
is just barely detectable on satellite.
My interpretation is that a minor phreatic eruption occurred.
Here is a quick list of every volcano which is currently erupting.
Also, here are some volcanoes at raised alert statuses which are not erupting but could
erupt in the near future.
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