Since early July of 2019, the towering Mauna Loa shield volcano in Hawaii has been at a
yellow alert level.
In the slightly more than 3 year since, the volcano has undergone episodes of ground deformation
which were consistent with the volcano's shallow magma chamber slowly recharging.
All of this activity has on occasion generated swarms of earthquakes, one of which is ongoing
right now, representing another sudden increase in activity.
During the last 2 weeks, this has resulted in between 40 and 100 daily earthquakes.
Due to how long this earthquake swarm has been ongoing for, the shallowness the earthquakes
are originating at, and a change which showed up on tiltmeter sensors at the volcano, the
summit area of Mauna Loa was just closed off.
Additionally, the Hawaiian Volcano Observatory is now changing from weekly to daily activity
updates due to all of this unrest.
So, what exactly does all of this mean?
Is Mauna Loa about to erupt?
This video will answer these two questions and discuss the ongoing volcanic unrest.
For context, Mauna loa is the earth's largest active volcano, comprising approximately 51%
of the Big Island's area, and has been erupting for at least 600,000 years.
It contains a large summit caldera and two rift zones which have been the site of numerous
volcanic eruptions.
In the last 200 years, Mauna Loa has erupted 39 times, frequently sending large volumes
of molten rock downslope which have even reached the ocean in as little as 3 hours.
Since many major population centers such as Hilo and Ocean View lie adjacent to very young
lava flows, whenever this volcano erupts, a large chunk of the island is put at risk.
At the present, Mauna Loa is not showing any signs of an imminent or near imminent eruption.
However, this statement might be a bit misleading.
Prior eruptions at Mauna Loa have occurred during prolonged unrest episodes such as what
is ongoing right now, but signs that a volcanic eruption was imminent sometimes only showed
a few hours before an eruption began.
In other words, Mauna Loa is currently in an elevated state of activity where it could
theoretically produce a new volcanic eruption at any moment, and we would only have warning
of this most likely few hours beforehand.
Since 2000, episodes of ground deformation and earthquakes comparable in magnitude to
what is ongoing right now have only occurred on two occasions; during May of 2004 and between
late January and March of 2021.
You can thus say that what is ongoing is unusual, but remember, the last two times something
like this occurred it did not result in an eruption.
However, suppose that hypothetically tomorrow, massive amounts of ground deformation were
detected, which a mere 2 hours later led to an eruption.
Although there are no signs of this occurring, if it did, where would the lava flow?
The short answer is that sadly we do not know.
However, a recently published scientific paper seems to suggest that dike propagation since
2014 has somewhat favored a southward direction.
This suggests but does not prove that there is a slightly higher than average chance of
the next eruption occurring somewhere along the southwest rift zone rather than the northeast
rift zone.
Additionally, this same paper suggested that if a magnitude 6 or larger earthquake occurred
beneath Mauna Loa, then the chance of a closely followed eruption would be quite high.
Regardless, long term ground deformation is continuing at Mauna Loa.
These sensors in the last month have recorded 3 changes.
These was an increasing trend beginning on September 15th, a stronger increase on the
23rd, and another notable increase late on September 30th.
Thus, although an eruption is far from imminent it is safe to say that the odds of an eruption
occurring in the short to mid term future is some of the highest it has been in a given
month since Mauna Loa's last eruption in 1984.
Regardless, all of this activity is quite interesting considering that Mauna Loa is
currently undergoing its longest span without an eruption in the last 200 years, as generally
this volcano has erupted about once every 6 years during the last 3,000 years.
Thanks for watching!
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