Vesuvius

[bjdeming]

Per INGV's notice, it sounds like Vesuvius is swarming a bit but is well within normal limits and they're keeping the alert at normal levels.

Still, it probably should have its own thread for two reasons:

• To underscore what the boffins say about this not being connected to Campi Flegrei
• The fascination we have for it because of the Pompeii eruption in 79 AD

Mount Vesuvius is tricky to understand both in its own right and because it has been so extensively studied.

Some links to get started:

• INGV monitoring page (Italian) for the three volcanic threats to Naples
• Global Volcanism Program (GVP) page
• Eric Klemetti on "70 Years of Silence"
• A draft of my eBook chapter (uses authoritative references -- listed so you can explore them -- on background, the Pompeii eruption and also links to various information online including Civil Protection's "Plan Vesuvio" in case of emergency)

There are live cams galore online. Here are a couple videos I really like:

• Pompeii, by Zero One (follows the events as described by the paper referenced in my eBook chapter, which also explains how Vesuvius doesn't always go off this intensely):




But sometimes it does.

• The local Alpine Club climbing Vesuvius during winter, thirteen years ago (note -- when it went back to sleep in the 1940s, Italy did extensive tree planting on its slopes):

 

[bjdeming]

All is quiet. INGV shared a YouTube today in honor of the 1944 eruption. It's in Italian, but the visuals are spectacular.



This was one of the small-scale Vesuvian eruptions, believe it or not.

A larger one (but not Pompeii sized) occurred at the turn of the twentieth century. It's responsible for the current cone appearance (the surrounding caldera is from AD 79) and an American was there -- literally right on the summit with some pioneering Italian crazy people volcanologists.

He was an interesting fellow, though eccentric. When he learned that US newspapers were headlining his presence at the summit, he left, went down to Naples, sent a telegram to Mom to reassure her, and then went back up to the observatory. Vesuvius was violently erupting through all this. The Italian boffins hugged him when he returned -- they had figured he was running out on them.

 

[bjdeming]

A 3-pointer occurred at Vesuvius today, followed by two 1-pointer aftershocks.

Reportedly (autotranslated), INGV says it has nothing to do with the Campi Flegrei swarm that just ended.

Vesuvius also had a 2-pointer towards the end of the last Campi Flegrei swarm, but that was very deep. In a tweet about two hours ago, INGV gave the depth of this morning's shock as 0.4 km -- [layperson speculation] if this were magmatic, INGV would have already reported increases in seismicity, ground deformation, and other parameters as magma and magmatic fluids made their way towards the surface.

Along with the earlier 2-pointer, also associated with Campi Flegrei, my extremely uninformed guess is that these are triggered stress-relieving quakes -- not directly related to Campi Flegrei, but not immune to that caldera's tectonic influence, either [/layperson guess].

 

[bjdeming]

Apparently this morning's quake was right in the crater and, Sunday morning or not, they called a meeting (alert level has not changed for either volcano):

Campi Flegrei and Vesuvius earthquakes, summit in the prefecture: "Don't make a spectacle of the risk"​

This morning's meeting after the bradyseismic swarm and the tremors with the epicenter of the volcano's crater. Gigi Manzoni (mayor of Pozzuoli): "Tourism, commerce and the serenity of citizens are at stake here"

Emiliano Dario Esposito NapoliToday journalist April 28, 2024 1:38 pm

...

This morning a summit was held in the prefecture, in Naples, to take stock of the situation in light of the seismic events recorded in the last 48 hours in the Campi Flegrei and Vesuvius . Present, in addition to the mayors of the affected areas and the prefect Michele of Bari, were the Regional Civil Protection, the ASL Napoli 1, the ASL Napoli 2 Nord, representatives of the police forces and the Vesuvian Observatory....

-- Source (autotranslated; the two links above were in the article and are in Italian)

 

[bjdeming]

INGV just released the April bulletin (2024 04 in this PDF list). It's beautiful, in-depth -- and written in more Italian than my little apps could handle well.

I did get the general gist, though with a couple of fanciful translation excursions -- in sum, Vesuvius is still sound asleep; they note in the report body, under deformation, that both the Great Cone and the offshore shallows where magma has fed before are actively subsiding, which is good:

5. Volcano's summary framework in April 2024 and ratings

1) Sismology: The Vesuvio permits a bottom seismic with 125 registered earthquakes (MD Max = 3.1 ± 0.3) of which 100 localized, mainly in the crater area with depth strongly focused in the first kilometer. One alone has been at the base of the north-western slopes of the volcanic building, to a depth of about 9 km.

2) Deformations: GNSS, Tiltmetric and Searemorate data detections due to volcanic sources are detected.

3) Thermography: Permanent thermal camera data show a trend of the maximum surface staircase temperatures on the average values of the previous months, albeit sensitive swinging. MABILIC METHODS MABILITY Move the substantially stationary trend of maximum temperature.

4) Geochetics: No significant variations in the geochemical parameters acquired. Monitoring data indicate the continuation of the 19th-century decline in the hydrotromal activity within the Craters of Vesuvius.

Based on the current framework of volcanic activity above outlined, no elements are evoked to suggest significant short-term evolutions.

N.b. Any changes in monitored parameters that may result in a different evolution of the above-mentioned phenomena will be the subject of investigation promptly communicated.

 

[bjdeming]

This 2019 video below shows the Great Cone as a cover image, and that's what they climb up in the video.

The area outside the cone on that cover image is, I believe, partly the caldera formed during the AD 79 Pompeii eruption and partly an older shield volcano called Somma that Vesuvius burst out of in Pleistocene times.

Note the views of Naples -- on the other side of town, low and indistinct, is Campi Flegrei.

The topography of the Great Cone itself was reportedly most strongly shaped by a powerful eruption in 1906 that reportedly was awesome.

Here it is 113 years later:

 

[bjdeming]

Again, reassuring information in INGV's bulletin (Italian) for May (Maggio) -- per GT: "... the increase in the number of events has been recorded in recent years is essentially linked to low energy seismicity confined to the crater area and detectable at the OVO station (Vesuvian Observatory Headquarters) only on some occasions."

The Great Cone is settling.

When it's time for another eruption, magma and fluids will have to rise from depth, triggering seismometers and other monitoring methods well before the actual event.

 

[bjdeming]

All is quiet (also at Campi Flegrei, per INGV's bulletin today). Just read Dr. Clive Oppenheimer's description, in Eruptions That Shook The World, of what the worst-case scenario that the Italians have modeled their Plan Vesuvio on would possibly look like. It's lengthy but interesting:

...This hypothetical scenario is based on the largest eruption of the volcano since 79 CE, which took place in 1631, claiming up to one thousand lives. Since all has been quiet on the mountain since 1944, renewed activity would very likely involve fracturing of rock as pathways re-open between subterranean magma bodies and the surface. This would generate earthquakes, some of which could be damaging. The cumulative effects of seismic shaking would increasingly take their toll on the building stock within a few kilometres of the volcano. Eventually, hydrovolcanic explosions would be likely once the conduit reached the water table; these would also be associated with strong earthquakes. With a fully opened magma conduit, sustained eruption would follow, with a tephra column climbing up to 20 kilometres above sea level. Tephra fallout would result in extensive building damage but the location of the worst-affected zones would depend strongly on prevailing wind directions at various heights in the atmosphere. While it is possible to model expected building damage statistically, the fact that one cannot know until the day of eruption which way the wind will carry tephra represents a major uncertainty in risk control (this point was illustrated vividly in the case of the Eyjafjallajökull eruption in 2010). A total area of around 1500 square kilometres, home to nearly two million people, could be affected to varying degrees by the immediate impacts of a future eruption of Vesuvius. As occurred during the 1631 event, the eruption column would likely founder at some juncture, generating pyroclastic currents that would rush down the flanks of the volcano, potentially affecting an area of more than two hundred square kilometres. They would even be funnelled to some extent by streets and buildings as has been deduced from studies of the deposits that buried Pompeii. The dynamic force of the flows and their entrained large chunks of volcanic and building debris, combined with their searing temperatures, would devastate the building stock and threaten the lives of all caught either inside or outside. There would be a further wider area at risk from firestorms as hot tephra would ignite buildings and fuel tanks and supplies. Of course, there will be wider impacts and other hazards of future activity, including major disruption to aviation and shipping. Structural failure of the volcanic edifice could also occur, triggering landslides and, potentially, caldera formation. In the waning stages of an eruption, mixing of ground water and magma within the conduit could produce hydrovolcanic explosions, while rainfall would redistribute the fresh tephra deposits, generating destructive mudflows. And it is feasible that the next eruption culminates in something bigger than a re-run of 1631.....

Again, that's the worst-case scenario as chosen by the authorities (some experts think it should instead be one of the more intense ancient ones that Dr. Oppenheimer goes on to describe).

As far as this layperson knows from her reading up on the Decade Volcanoes, a lot depends on when the big V wakes up again -- if it has just been dormant since 1944 and reawakens fairly soon, it might be less violent (although 1631 was a part of the activity cycle that began with AD 79's Pompeii eruption).

If that cycle is over, Vesuvius might sleep for centuries before waking up with another such blast as strong or stronger than AD 79.

Its current cycle status is not something that anyone has been able to determine, per my very limited reading.

But they do have a plan for the region now, reviewed and updated frequently, and that's GREAT.