As of August 21st, 2022, there are 48 volcanoes actively erupting on the planet.
One of these erupting volcanoes is Ebeko in Russia, which is located on one of the Kuril
Islands.
Ebeko has several fairly large volcanic craters, which have frequently been the site of small
to medium sized explosive eruptions such as seen in this photo.
With this being said, here are this week's major volcano related news stories.
In the Philippines, satellite data suggests that two volcanoes, Bulusan and Mayon, might
be showing signs of unrest through a possible magmatic uplift signature.
Meanwhile in Chile, a suspicious hybrid earthquake was observed at a volcano with a large caldera,
Mount Hudson.
And, in American Samoa, two volcanoes are showing signs of unrest through a series of
earthquakes with a likely magmatic signature.
As a result, the alert level was raised at both Ta'u and Ofu-Olosega from white indicating
a lack of thorough monitoring equipment to yellow indicating overall increased activity.
The reason why two volcanoes had their alert level raised rather than one is owed in part
due the uncertainty of exactly where the earthquakes are originating.
This is because before this week, the three islands which have an overall population of
about 1,100 did not have any active monitoring stations.
Two were put in place during the latest unrest, presenting data that suggests the earthquakes
caused by the movement of magma are originating somewhere beneath the island of Ta'u rather
than close to Ofu-Olosega or a submarine seamount to the east.
These earthquake swarms have been ongoing since July 26th of 2022, involving many hundreds
of earthquakes, the largest of which were in the magnitude 2 to 3 range.
During some hours, 20 earthquakes are being recorded, although most are too small to feel.
While the exact age of several recent vents on the 3 islands is unclear, what is clear
is that both volcanoes have produced eruptions in the Holocene indicating the last 11,700
years.
Ofu-Olosega produced at least one explosive tuff ring forming eruption during this time
period and a submarine explosive eruption just offshore of its landmass in 1866.
On the other hand, the exact age of recent eruptions on Ta'u is unclear, but several
spatter cones, cinder cones, and tuff cones can be found on its flanks.
These vents are generally aligned to two chains of activity suggesting that if an eruption
was to occur these areas would represent the most likely spot for one to begin.
Although the ongoing seismic activity is highly unusual, the vast majority of times a magmatic
intrusion does not result in a new volcanic eruption.
In the Philippines, the Bulusan volcano has been at a raised alert level since June 5th
of this year when an unexpected phreatic eruption occurred.
After a second phreatic eruption a week later, this volcano remained at a heightened state
of unrest with high levels of sulfur dioxide gas emissions but has not produced another
eruption.
However, a recent satellite INSAR dataset suggests that magmatic uplift is still ongoing
at this volcano.
Despite the noise in this map due in part to thick vegetation and frequent rainfall,
Bulusan clearly shows up as a high point.
Additionally, there is another potential magmatic uplift signature to the north at the Mayon
volcano which has not erupted since 2019.
Although this uplift signal is stronger than the confirmed one at Bulusan, I have been
unable to independently verify from Phivolcs that it is a true signal.
In southern Chile is one of the most explosive active volcanoes in all of South America.
There, the Mount Hudson volcano has repeated produced plinian eruptions in the last 10,000
years, with at least 3 eruptions being larger than the 1980 eruption of Mount Saint Helens.
Its last major eruption occurred in 1991 and was assigned a volcanic explosivity index
of a 5.
Thus, whenever any sort of activity occurs at this volcano, it is closely monitored.
An unusual volcanic quake known as a hybrid earthquake struck the volcano on August 14th
at around 4:30 local time.
While seemingly an isolated event, hybrid earthquakes originate due to the movement
and resonance of fluids within the volcano's conduits.
In other words, a small change may have occurred in its hydrothermal system.
While suspicious, this quake was not all that unordinary.
A similar event also occurred on March 7th of 2022 and that did not result in a volcanic
eruption.
Thus, its alert level remains at green.
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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