The reason why excavations of the Villa of the papyrii in Herculaneum had to end is usually cited to be "gas invading the tunnels". That is a common problem in coal mining. However, volcanic deposits, unlike coal, do not release toxic gas. What kind of gas is this referring to?

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    Volcanic gas can be highly toxic, see the following article on Wikipedia for a basic understanding: en.wikipedia.org/wiki/Volcanic_gas#Hazards One can imagine that the release of such poisonous gases in an enclosed space would render the workers more than reticent to work in said space.
    – BOB
    Dec 10, 2017 at 21:22
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    As far as I'm aware, we don't know the answer. The excavations were carried out in the 1750s, and I don't think they tested the gasses to see exactly what they were dealing with. Dec 11, 2017 at 2:49
  • A reading of the Wikipedia article mentions that it may have had more to do with disagreement from the owners of property under which they were digging. There is a reference to this claim on the Wikipedia age but, the site it links to didn't seem to offer any further information or any at all for that matter.
    – BOB
    Dec 11, 2017 at 3:03
  • @BOB Volcanic gas can be toxic, but Villa of the papyri is not that close to a vulcano. It is buried in vulcanic ash and mud, which then sat for 2k years. The disagreement with owers of property is todays situation, and since i belive the bourbon king dit not bother with this kind of stuff in 18th cetury, i assume someone on Wikipedia confused this. Anyway, gas was cited as a problem, legal problems nonwithstanding.
    – HannesH
    Dec 11, 2017 at 22:16
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    I agree that it would be interesting, but my point is that if the information wasn't recorded in the 1750s, the best we can do today is to speculate. Dec 11, 2017 at 22:28

1 Answer 1


If we look at the book Buried Herculaneum, By Ethel Ross Barker (1908) we find on page 18 a discussion of these excavations:

To the actual physical difficulties of the work was added great discomfort from the cold dark and damp and from occasional exhalations of poisonous gases especially of carbonic acid gas and sulphuretted hydrogen during the excavations on the Villa.

The terminology is 1908, but seems to mesh up with what is expected in volcanic caves. Hydrogen and Sulfur gases and carbon dioxide type compounds. Looking at the PDF Hazards of Volcanic Gases Table 57.1 lists Carbon Dioxide, Sulfur Dioxide and Hydrogen Sulfide as dangers in volcanic cave environments.


Note that there are major differences between the characteristics of the flows received by the cities of Pompeii and Herculaneum. From a PBS page

Pompeii, lying to the east and south of the mountain, was buried under approximately 40 feet of fine ash. Deadly at the time, this layer of ash was relatively easy to excavate seventeen centuries later when the city was rediscovered. Herculaneum, on the other hand, lying to the west of Vesuvius, experience its full fury with a hot thermal blast, poisonous gasses, and a flow of molten volcanic mud that, when cooled, buried the remains under an 80 foot deep bed with the density of concrete. For this reason Herculaneum has been much more difficult to excavate, and some areas of the city have remained inaccessible due to pockets of trapped gas.

So this article seems to equate the gases with those of volcanic origin as well.

  • What is expected in volcanic caves is what vulcanos bring about. Villa of the papiri is buried in vulcanic deposit (Tethra), which had 2k years to gas out, and it's not on the slopes of the mountain.
    – HannesH
    Dec 11, 2017 at 22:14
  • I wasn't trying to show the volcanic gases are from an active source, just showing the comparison to the gases claimed to be present by the source I located.
    – justCal
    Dec 11, 2017 at 22:42
  • @HannesH updated with a little more information.
    – justCal
    Dec 11, 2017 at 23:01
  • Interesting point. I wonder if not this is a reference to the problem at villa of the payrii itself though. While the mud was hot, it was not 'molten', but water based. Also, while maybe dense as concrete, the deposits are nowhere near as hard as concrete. I was at the villa of the payryrii and found the material to be loose and porous, with variations of strata. I do not belive gas can be trapped here, especially since ground water is continously passing through.
    – HannesH
    Dec 12, 2017 at 1:58
  • I did notice in one source I was reading, they mentioned a lot of the previous excavation had just 'moved' the material from one excavated area into another. This material would be looser then the original, untouched flows. Perhaps this was the material you encountered?
    – justCal
    Dec 15, 2017 at 1:28

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