If you head west from the city of Naples you will begin to see large craters, altered regions,
and calderas in the ground, representing vents of the Campi Flegrei supervolcano.
On September 27th, at 3:35 am local time, this very region produced a magnitude 4.2
earthquake, causing minor shaking to be felt by several million people.
What had just occurred was Campi Flegrei's largest earthquake in at least 40 years, and
this event happened alongside two other unusual events.
This earthquake was struck at 3 kilometers depth, exactly where the shallowest magma
at this volcano is expected to be.
The magnitude 4.2 quake occurred as part of a swarm which as of the writing of this video
has consisted of more than 75 volcano tectonic earthquakes.
However, the biggest change relates to the amount of ground uplift which is occurring
at this volcano.
As, beginning on September 12th, the amount of ground deformation spiked to its highest
levels seen since 1985.
In other words, the peak ground uplift rate due to the intrusion of magma at 3 kilometers
depth in a laccolith has increased from 18 centimeters a year to 75 centimeters a year.
While this dramatic increase could be temporary, if it continues it might be that Campi Flegrei
is right now undergoing its first seismic crisis since 1985.
What exactly might this mean?
Well, since 1950, Campi Flegrei has undergone 3 seismic crises during which ground deformation
rapidly increased due to a temporary increase of magma flowing from 8 to 3 kilometers depth.
During these periods which lasted between 2 and 4 years in length, ground uplift increased
to between 35 and 121.4 centimeters a year, resulting in highly frequent small magnitude
earthquakes, with the uplift itself sometimes leading to building damage.
Why exactly might a building be damaged?
Simply put, structures are not neccessarily designed to be pushed upwards by 5 meters
or 16.4 feet since 1950, in an uneven manner.
Yet, this is exactly what has occurred since 1950, with this uplift being centered at the
Pozzuoli site.
Although we only have a brief dataset to work with so there could be a large margin of error,
between September 12th and September 24th, the ground has risen by a maximum of 2.5 centimeters.
If this rate were to continue for a year, it would not only surpass the maximum uplift
rate measured during the 1950 to 1952 crisis, but also the 1968 to 1972 crisis.
Only the 1982 to 1985 crisis had a higher rate of maximum uplift, that specifically
ended up triggering the evacuation of 40,000 people and involved up to 121.4 centimeters
of uplift a year.
If this uplift does continue, I caution that evacuations similar to what occurred during
1984 might occur.
Luckily, there have not been any major changes in fumaroles or other geothermal features,
or signs that an imminent eruption will occur anytime soon.
As, in my opinion, the current threat if this uplift continues is not an unexpected volcanic
eruption but rather potential damage to buildings near the uplift's center where cracks and
foundation damage could hypothetically appear, possibly even destabilizing some entire structures.
You might wonder why I do not believe this current unrest will lead to a volcanic eruption
in the short term.
First of all, magma does not yet exist at shallow enough depths to directly trigger
an eruption in my opinion, like last occurred in 1538.
Instead, in the 5 step cycle Campi Flegrei seems to undergo, we are merely in step 3;
a period of heightened ground deformation where an eruption is highly unlikely.
I would only be concerned about an eruption becoming possible if ground deformation for
more than 12 months exceeded 2 meters a year, like last witnessed in 1537 to 1538, where
some areas reportedly rose by as much as 9.1 meters or 30 feet a year.
In summary, a new seismic crisis similar to what Campi Flegrei experienced between 1982
and 1985 may now be ongoing once again, but a volcanic eruption anytime soon in my opinion
seems highly unlikely.
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