As of September 25th, 2022, there are 50 volcanoes actively erupting on the planet.
Out of these 50, 4 are within the United States, and of this group, the one with the longest
ongoing eruption is the Great Sitkin volcano within Alaska whose eruption is now in its
489th day.
This volcano is located in the remote Aleutian Island chain with its closest city being Adak,
26 miles to the southwest.
Great Sitkin is a variable composition stratovolcano whose most notable feature is an old collapse
scar which formed when a large section of the volcano collapsed to the northwest many
thousands of years ago.
With this being said, here are this week's major volcano related news stories.
Off the coast of Madagascar on the French Island of Reunion, a new volcanic eruption
began at the Piton de la Fournaise volcano.
Meanwhile, in Hawaii, the towering Mauna Loa shield volcano produced a new earthquake swarm,
marking only the latest in a sequence of events since the volcano has been at a raised yellow
alert level.
And, in New Zealand, the alert level of the Taupo supervolcano for the very first time
was raised.
This change in alert level was made on September 20th, when Taupo's alert level was raised
from 0 indicating normal levels of activity to 1 indicating minor volcanic unrest.
The immediate cause of this increase was the nature of ongoing activity at this massive
silica rich caldera system.
Since May of 2022, the ground centered around Horomatangi Reef which is where many of this
volcano's recent eruptions have occurred has been continually uplifted at a rate of 6 centimeters
a year.
While this might seem small, it is quite scientifically significant as according to Geonet, the uplift
is being caused by both the movement of magma and hydrothermal fluids.
All of this activity has generated more than 600 earthquakes, which although being much
larger than the number of quakes seen in a typical year is less than the number seen
in both 2008 and 2019.
While Taupo has not produced an eruption since 260 CE, which followed a highly explosive
VEI 7 eruption in 233, this volcano like all large calderas has produced cycles of unrest
and uplift.
In the last 150 years 17 episodes of volcanic unrest have been recorded, several of which
had more severe effects than what is current ongoing such as during 1897, 1964 to 1965,
and 1983 to 1984.
The alert level was raised this month in 2022 as there is now less ambiguity about what
the volcanic unrest represents due to recent scientific research on Taupo.
In Hawaii, while the Kilauea volcano has been erupting, the Mauna Loa volcano has been at
a raised alert level since early July of 2019.
During this period, the volcano has undergone episodes of ground deformation which were
consistent with the volcano's shallow magma chamber slowly recharging.
While an eruption is by no means imminent, the activity has resulted in semi frequent
swarms of earthquakes due to the movement of magma and the magmatic fluids under Mauna
Loa's summit.
One such earthquake swarm occurred on September 23rd beginning at around 9:00 am local time,
involving 84 earthquakes which were centered underneath its summit, but were of overall
low magnitudes per the U.S. Geological Survey.
However, what was most notable about these quakes were their depth, as they originated
above sea level at between 6600 and 12000 feet underneath Mauna Loa.
This suggested a potential change in the underlying magma storeage system of the complex, although
this is not necessarily the only possible cause.
While this might seem a bit worrying, the earthquake swarm seemingly stopped on September
24th, and longer term seismicity at the volcano is still below levels that were recorded during
the winter of 2021.
On Reunion Island, a new volcanic eruption began on September 19th at a fissure 1600
meters southwest of Piton de la Fournaise's summit, occurring at a site just east of both
the Rivals crater which erupted in 1937 and the Kala Pele crater which erupted from 2014
to 2015.
This eruption only began after another failed magmatic intrusion on September 7th.
It is now day 7 of the eruption, and although the rate of lava effusion was highest when
the eruption first began, producing up to 100 foot or 30 meter tall lava fountains,
it has since decreased before stabilizing at a lower level.
Because of the stabilization, the eruption is likely to continue into the following week.
Here is a quick list of every volcano which is currently erupting.
Also, here are some volcanoes showing signs of unrest which are not erupting but could
erupt in the near future.
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