As of September 23rd 2023, there are currently 47 volcanoes which are actively erupting around
the planet.
One of these erupting volcanoes is the Ruby Seamount which is a submarine volcano considered
part of the United States in the Northern Mariana Islands.
With a summit lying at a depth of 230 meters or 755 feet below sea level, Ruby Seamount
erupted for its first time in 28 years on September 15th of 2023, producing a series
of underwater explosions and a large plume of discolored water visible from satellite.
While this eruption in my opinion does not pose any risk to those that live on any of
the many regional islands, I would still recommend that ships and people keep a minimum distance
of 10 miles or 16 kilometers away from its summit.
With this being said, here are this week's major volcano related news stories.
In Russia, a Kuril island volcano erupted anew, albeit in a seemingly low intensity
eruption.
Meanwhile, in Indonesia, ground uplift is ongoing at the Gamalama volcano, and this
is quite worrying.
And, in what is this week's top story, fairly rapid ground deformation began occurring at
the tall and potentially dangerous Semeru volcano on the island of Java.
This new uplift was first detected on September 16th, although it may have been ongoing since
as early as September 4th.
During this 12 day timespan, the summit area of this volcano has been pushed upwards by
12 centimeters, equaling 1 centimeter a day.
While Semeru is actively erupting right now, the new high rate of uplift likely signals
the influx of a new and large batch of magma.
This intrusion, if it continues, is likely to place a significant amount of highly pressurized
gas beneath Semeru's active lava dome, which currently acts as a plug.
Gas could then significantly build in pressure until it becomes so great that it cracks overlying
rock, exploding upwards and releasing long reaching pyroclastic flows in a sub-plinian
or large scale vulcanian eruption.
Such intrusions of a nearly identical appearance along with associated ground deformation occurred
in the days to months before Semeru produced two highly destructive eruptions on December
4th 2021 and then again on December 4th 2022, involving 13 kilometer long and reportedly
19 kilometer long pyroclastic flows, respectively.
However, while 1 centimeter a day of uplift is quite significant, it is still less than
the 2 centimeters a day seen during a period before the 2022 eruption occurred, which suggests
that if a large eruption was to occur, it would be smaller than witnessed in 2022.
Thus, in my opinion, a possible VEI 3 eruption could occur at some point in the next 3 months
at Semeru, although it is not a complete guarantee that such an eruption will occur at all.
Regardless, please keep out of the current stated exclusion zone, effecting areas up
to 17 kilometers away from Semeru's summit.
Meanwhile, on Indonesia's Ternate Island, there is an increasing potential concern at
least in my opinion regarding the central Gamalama volcano.
As, there appears to be an active magmatic intrusion ongoing 2.5 kilometers offshore
of Gamalama's northwest flank, which is seemingly occurring alongside an increased rate of earthquakes
at a depth of 3 to 9 kilometers in the same location.
This suggests that magma is currently at a depth of 4 kilometers and is actively intruding
upwards, pushing up overlying ground.
Here is why this is a major problem if this magma reaches the surface.
The last time a flank eruption occurred in this approximate location, it formed a 710
meter or 2330 foot wide maar in a powerful explosion, releasing a pyroclastic flow that
erased several villages off the map, leading to 1,300 deaths.
While there is no guarantee that this magma will reach the surface or erupt in a similar
manner, the fact that it may even be centered offshore suggests that if it does erupt, a
highly explosive manner would be quite likely, perhaps even generating a regional tsunami
from such an explosion.
Thus, if this magma continues to ascend upwards, a large scale evacuation of the 200,000+ population
of Ternate might be required.
However, as the current volcanic unrest is still being analyzed, such an evacuation has
not been considered yet and likely only will be ordered if an eruption becomes likely.
In Russia, the remote Sarychev Peak volcano erupted anew on September 21st, as thermal
signatures on its summit appeared to suggest that a small lava dome was beginning to slowly
grow in its summit crater.
However, I have potential evidence that this eruption may have been ongoing since September
9th, as that marks the first satellite detection of increased heat signatures.
While this eruption could remain as a small scale effusive event, it is quite likely to
escalate in my opinion to a moderate volume explosive eruption at some point in the future.
Here is a quick list of all of the world's volcanoes which are currently erupting.
Additionally, here are some volcanoes showing signs of unrest which are not erupting as
of the recording of this video on September 23rd of 2023.
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