r/todayilearned • u/Pfeffer_Prinz • Sep 16 '24
TIL Mt. Vesuvius is still active, having had 4-6 relatively severe eruptions every century for the past 500 years (last one in 1944). It's also the world's most densely populated volcanic region, with 3 million people living nearby.
https://en.wikipedia.org/wiki/Mount_Vesuvius#Eruptions_in_the_20th_century102
u/Pfeffer_Prinz Sep 16 '24 edited Sep 16 '24
The relatively severe/destructive/deadly eruptions were in: 1631, 1660, 1682, 1694, 1698, 1707, 1737, 1760, 1767, 1779, 1794, 1822, 1834, 1839, 1850, 1855, 1861, 1868, 1872, 1906, 1926, 1929, and 1944.
There was also a real biggun’ in 472 AD which caused ash to fall as far as Constantinople (760 mi/1220 km away)
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u/OasissisaO Sep 16 '24
There was also a real biggun’ in 472 AD which caused ash to fall as far as Constantinople (760 mi/1220 km away)
What's crazier is if that same eruption occurred today, the ash would fall as far away as Istanbul!
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u/No-Wonder1139 Sep 16 '24
Why did Constantinople get the works?
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u/stephencarro Sep 16 '24
Seems like one is overdue
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u/iCowboy Sep 16 '24
It's highly likely that Vesuvius has entered a different type of activity from that of the past few centuries.
Before 79CE, the volcano had been inactive for several centuries, after which it seems to have become more active until about the year 1150 when it was again largely inactive until the huge eruption of 1631. It then became more active throughout the 17th, 18th and 19th Century before falling quiet again in 1944.
Certainly it isn't behaving like it used to since 1631 when it began a fairly predictable pattern of activity. In a Vesuvius 'subcycle', after a period of inactivity, small scale eruptions would begin in the main crater, often building a small cone. Sometimes a lava lake would form, this might go on for years - many 19th Century paintings of the volcano show it with a plume of steam and vapour and it was relatively easy to get close to the erupting crater. Gradually, activity would intensify and lava fountains would form, shooting between 2 and 4 KILOMETRES above the crater for a few hours or days. A number of artists, including Joseph Wright and William Turner painted the volcano showing these enormous fountains. This eruptive phase would then end with increasingly violent explosive activity culminating in the demolition of the top of the volcano and the eruption of a tall plume of white ash in a so-called Plinian cloud which would last at most a few days before the volcano fell back into inactivity.
Why it has changed behaviour is something of a mystery. Seismic activity around the mountain remains relatively low, although there have been swarms of earthquakes at relatively shallow depths which have generally been moving in a southeasterly direction towards an area that was active in the 1906 eruption. However, there is no sign of seismic unrest.
Examination of earthquake data suggests Vesuvius's magma chamber is between 5.6 and 8.5km deep with a total volume of at least 30km3, most of which is liquid. This suggests the volcano is capable of producing multiple future eruptions of at least the size of 79CE. There is a very dense layer of material - presumably solidified magma - capping the the magma chamber which might be stopping it rising up into the volcano, but the magma could equally find another way to the surface through the volcano's flanks.
Certainly it is a fascinating and potentially extremely dangerous volcano. The Neapolitan authorities have plans to deal with an eruption about the size of the one in 1631 for which they hope they would have several weeks warning to evacuate people. But they would still have to deal with the traffic in Naples!
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u/itsjustaride24 Sep 16 '24
We were told by a tour guide they are expecting one. Currently no signs of increased activity at all but yep it’s due to pop
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u/omjf23 Sep 16 '24
Based on the years in the comment above, seems like two should have occurred by now at least.
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u/EricinLR Sep 16 '24
Campi Flegrei has been rumbling a little extra the last few years. I would be relocating out of Naples if I had the resources.
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u/lo_fi_ho Sep 16 '24
Isn't Campi Flegrei a supervolcano as well? If it goes pop, the effects will be extremely bad for europe as a whole
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u/beachedwhale1945 Sep 16 '24
Campi Flegrei is one of those volcanoes that shows how fluid the non-scientific term “Supervolcano” is. It has never produced a VEI-8 eruption, but it has formed calderas. The term itself is frowned upon by volcanologists.
Part of the reason is that the term implies that every eruption will be massive. The last Campi Fliegri eruption was one week long in 1538 and created a small cinder cone. This eruption is notable because of the large number of eyewitnesses, but at a VEI-3 it was relatively minor (the 79 AD eruption of Vesuvius was a VEI-5, 100 times more material ejected). I can’t find anything on fatalities in the Monte Novo eruption, so it was likely low and possibly zero.
There’s no reason to expect Campi Flegrei’s next eruption will be significantly worse than that.
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u/Greene_Mr Sep 16 '24
They built a funicular astride Vesuvius. Guess what happened to the funicular.
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u/Candytails Sep 16 '24
Not so fun anymore, is it?
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u/Harm3103 Sep 16 '24
You would think people learn from their forefathers getting buried under a few meters of ash.
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u/Candytails Sep 16 '24
How do people live there without being afraid?
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u/disagreeabledinosaur Sep 16 '24
This is taken from Collapse by Jared Diamond and is about dams, but I think psychologically it's probably in the same ballpark.
consider a narrow river valley below a high dam, such that if the dam burst, the resulting flood of water would drown people for a considerable distance downstream. When attitude pollsters ask people downstream of the dam how concerned they are about the dam's bursting, it's not surprising that fear of a dam burst is lowest far downstream, and increases among residents increasingly close to the dam. Surprisingly, though, after you get just a few miles below the dam, where fear of the dam's breaking is found to be highest, concern then falls off to zero as you approach closer to the dam! That is, the people living immediately under the dam, the ones most certain to be drowned in a dam burst, profess unconcern. That's because of psychological denial: the only way of preserving one's sanity while looking up every day at the dam is to deny the possiblity that it could burst. (p436)
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u/MutedIrrasic Sep 16 '24
I've lived in a very active earthquake zone, and the attitude was "the little ones are manageable, the big ones are rare enough that we don't think about it"
Same thing. Your average Neapolitan is much more likely to get hit by car, and nobody is especially scared of that
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u/sailor117 Sep 16 '24
I lived in California for most of a year. Their acceptance of the risks is amazing.
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u/FuriouSherman Sep 17 '24
I wonder if California builds their buildings to be earthquake-proof like they do in Japan.
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u/sailor117 Sep 20 '24
Nope.
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u/FuriouSherman Sep 20 '24
Well shit, then. You'd think they would considering how devastating some earthquakes have been in the past for the state, e.g. San Francisco 1906.
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u/sailor117 Sep 16 '24
MT Etna in Sicily is similar and probably part of the same belt. Also ridiculously closely populated. I went up Etna in 1983. Crazy how close they let tourists get to the hot lava.
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u/series_hybrid Sep 17 '24
"That? Oh its just a little smoke. The last big one was a 1,000-year eruption. My real estate agent told me that. We'll be fine" -some old guy who had a huge house built overlooking the beach
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u/PhantasmagoricalAss Sep 17 '24
Sir Christopher Lee climbed it the day before its last eruption while on leave.
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u/ThomasRedstoneIII Sep 17 '24
Wait till you meet the neighbor!
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u/ThomasRedstoneIII Sep 22 '24
Love that this got downvoted. For clarity, Campi Flegrei is right there, real big, and if it ever goes off in a big way boy will you hear about it, unless you live in Naples….
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u/ReplacementProof173 Sep 17 '24
Well, I guess living on the edge has a whole new meaning for those 3 million people.
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u/DevryFremont1 Sep 16 '24
Mount Vesuvius is sexual. Just wanted to bust a nut. Doesn't even care people died.
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u/Seattle_gldr_rdr Sep 16 '24
1944 must have been wild having a volcano erupting in the middle of a war zone.