As of March 6th, 2022, there are 51 volcanoes which are actively erupting.
This list of volcanoes includes Suwanosejima in Japan, which is a volcanic island off the
southern coast of Kyushu.
It is most famous for its 1813 to 1814 eruption, when the eastern flank of the volcano collapsed
into the ocean, forming a small horseshoe shaped caldera.
It also includes the Nevados de Chillan volcano in Chile, whose gray edifice is typically
covered in thick snowpack as it stands at 3,180 meters or 10,433 feet in height.
With this being said, here are a few of this week's major volcano related news stories.
In Japan, the Mount Ontake volcano is continuing to show signs of unrest via a series of volcanic
earthquake swarms.
Meanwhile in Indonesia, the decade volcano known as Mount Merapi produced a series of
energetic pyroclastic flows while at the same time two lava domes were growing on its summit.
And in Alaska, the Davidof volcano is continuing to produce a sequence of very shallow earthquake
swarms.
Due to these earthquake swarms, it has been placed at a raised yellow alert level since
January 26th.
The Davidof volcano is located far away from the Alaskan mainland in the remote western
reaches of the Aleutian island chain.
As part of the "Rat Islands", there are no nearby settlements, and this volcano is inbetween
two other active volcanoes, Segula to the west and Little Sitkin to the east.
This volcano is sometimes colloquially referred to as the "Alaskan Krakatoa" as it suffered
a major caldera collapse around 2 million years ago.
This large-scale eruption formed a 2.5 kilometer or 1.6 mile wide caldera, which left a prominent
circular scarp in the remaining 5 islands.
Although we don't yet know much about this volcano, one thing is clear; it has not erupted
in the last 10,000 years.
This is why it was a surprise when a series of earthquake swarms with a magmatic signature
to them occurred underneath the volcano beginning on December 10th of 2021.
They occurred at unusually shallow depths, some of which were only 100 meters below the
island.
The largest of the several hundred earthquakes which occurred had a magnitude of 4.9.
Then, the earthquake swarm ended.
It began anew on January 26th of 2022 and has continued to the present.
Although there hasn't been a truly notable change, earthquake activity has slightly increased
over the last 10 days.
All of this activity is quite strange considering that beforehand the island has not produced
a single earthquake swarm since monitoring equipment has been installed.
While these earthquakes could technically be caused by nearby fault lines, I think they
are volcanic as they have been occurring for too long to simply represent an aftershock
sequence.
These earthquakes are likely caused by a combination of an intrusion of magma underneath the volcano
at several kilometers depth and heated water.
Although an eruption appears unlikely for the immediate future, it would not be the
first time of the 21st century that an Alaskan volcano erupted after more than 10,000 years
of inactivity.
In Indonesia, one of the nation's most dangerous volcanoes in Mount Merapi.
More than 1 million people live within reach of its long travelling pyroclastic flows,
so monitoring the activity at this volcano is quite important.
It has been erupting continuously since December 31st of 2020, and over time has built two
lava domes on its summit.
These have both expanded at a very slow rate, and now have a volume of 1.58 and 3.23 million
cubic meters.
The southwest facing dome has been showing signs of structural instability as of late,
which in the past week created 173 small lava avalanches.
A more explosive episode also occurred, which created a pyroclastic flow that travelled
1800 meters.
Overall seismic activity at Merapi remains high, so although a significant eruption does
not appear imminent, a large dome collapse could occur with little warning.
In Japan, the Mount Ontake volcano has been at a raised alert status since February 23rd,
when a swam of 80 earthquakes occurred underneath its edifice.
This volcano has a habit of producing large phreatic eruptions with little or no warning,
so a 1 kilometer exclusion zone was declared.
Since then, seismic activity and ground deformation at the volcano have greatly decreased, although
they still remain at above normal levels.
While there were 17 volcanic earthquakes on February 25th, there were only 3 on March
1st.
A phreatic volcanic eruption still remains possible, but now seems increasingly unlikely.
Here is a quick list of every volcano which is currently erupting.
Also, here are some volcanoes showing signs of unrest which could erupt in the near future.
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