Vesuvius A.D. 79: How the people in Pompeii died.

Biretta tip to rogueclassicism, which directed me to an article about how the people in Pompeii died during the famous eruption of Vesuvius.  There is a scholarly article called "Lethal Thermal Impact at Periphery of Pyroclastic Surges: Evidences at Pompeii" here, but a less dense summary here.

Let’s have a taste.

How did the victims of the Plinean Eruption of Vesuvius die?
by Greg Laden

Even at the most extreme edges of the flow of stuff out of the volcano Pompeii, at the far edge of the mud and ash that came from the volcano’s explosion, the heat was sufficient to instantly kill everyone, even those inside their homes.

And that is how the people at Pompeii, who’s remains were found trapped and partly preserved within ghostly body-shaped tombs within that pyroclastic flow, died. They did not suffocate. They did not get blown apart by force. They did not die of gas poisoning. They simply cooked. Instantly.

That is the conclusion of a study just published in PLoS ONE by Giuseppe Mastrolorenzo, Pierpaolo Petrone, Lucia Pappalardo and Fabio Guarino, entitled Lethal Thermal Impact at Periphery of Pyroclastic Surges: Evidences at Pompeii.

[..]

And thus, Pompeii becomes an important data point. At Pompeii, the remains of hundreds of individuals were found in the pyroclastic deposits from the famous 79 AD eruption, the one documented by Pliny the Younger and memorialized in countless books, a few movies, and a museum exhibit or two.

Yeah, like this:

[youtube:http://www.youtube.com/watch?v=gtc29Yaynq4]

(Verily, one of Ernest Borgnine’s greatest films!)

The study modeled the physics of the eruption, tying a model to the ground with the physical and archaeological data. For context:

    The 79 AD Vesuvius eruption generated a sequence of six distinctive pyroclastic surges (S1 to S6) and flows with increasing power, which caused landscape modification as well widespread building collapse and fatalities [3]. The resulting ash deposits have thicknesses ranging from tens of metres near the vent to few millimetres at the flow periphery. In particular, the early three surges (S1 to S3) stopped ahead the northwestern walls of Pompeii, while the later ones (S4 to S6) over passed the town. The last two surges traveled up to a distance even exceeding 15 kilometres from the vent, whereas the S4 surge deposit least traces are confined within a few hundred of metres next to the south and southeastern walls.

The S4 surge, which deposited only a small blanketing of ash at the site, probably caused most of the fatalities in Pompeii. The 3 cm or so thick layer of ash was "emplaced suddenly in a single depositional event resulting from dusty gas mixture deflation in response to horizontal velocity and turbulence dumping at the flow termination."

In other words, it was like "phooofff" and everybody was dead and this dusting of ash was everywhere. And I don’t really mean to be flip about this … it is hard to imagine what is being described by this analysis in real terms.

Consider this: Imagine an area about 10 kilometers (just over 6 miles) around the volcano. Now imagine that area being covered with a blanket of very hot ashy air over the course of about 3 minutes. To help imagine this, pretend you are looking at the volcano when the explosion starts, and there is an airliner over the volcano heading for you at the same time. It is moving at top speed for such an aircraft, and when it reached you it has slowed to just over 100 mph. That represents the leading edge of the blanket of hot air and ash. Just at that moment, the blanket of air and ash deflates/dissipates, the air cooling and the ash settling. But first, all humans, probably all tetrapods (birds, mammals, etc) within that few miles of space have simply dropped dead. Since there is only a little ash, they are dirtied by it, but later, a larger deposit of ash is spewed out, and now all the dead are deeply buried. Or at least, that’s what I’m getting from this paper, more or less.

    … most of the victims are typically frozen in suspended actions (73% life-like stance, 27% sleep-like stance), showing as well as limb contraction (76%) and a large number of corpses presenting the pugilistic attitude (64%).

That "pugilistic attitude" bit is the appearance that the victim was fighting for his or life, but which actually occurs as a side effect of being cooked very quickly (or drying out more slowly in some cases). Everyone was killed and their bodies frozen in the position they were in at that time of instant death, plus a small bit of involuntary perimortem spasm. They were not suffocated, they were not killed by being blasted with an explosive force that knocked them down. They were cooked in situ.

    Finally, contrary to previous hypotheses, our findings based on the interdisciplinary volcanological and bio-anthropological study of the deposits and victims of the 79 AD Plinian eruption reveal that even at the extreme periphery of the S4 surge neither asphyxia nor impact force but heat caused the deaths. Actually, while impact force and exposure time to dusty gas dropped below lethal conditions, the pyroclastic cloud retained its high temperature thus being the main cause of instantaneous mortality for the Vesuvius area inhabitants, including people who were sheltered within buildings as far as in Pompeii.

The temperature was 250 to 300 degrees C, and the time of exposure was about 30 seconds or so. Death would have been during the first few seconds of that time. That temperature is enough to light gasoline and other fuels under certain conditions, but not enough to ignite clothing.

So, now you know how they died.

FacebookEmailPinterestGoogle GmailShare/Bookmark

About Fr. John Zuhlsdorf

Fr. Z is the guy who runs this blog. o{]:¬)
This entry was posted in Global Killer Asteroid Questions, Just Too Cool, SESSIUNCULA and tagged , , . Bookmark the permalink.

13 Responses to Vesuvius A.D. 79: How the people in Pompeii died.

  1. doanli says:

    Wow.

    This is one of my favorite bits of History to study. I had hoped they died from gas poisoning and that death was quick.

    I cannot imagine…somewhat akin to a nuclear bomb?

    Very, very sad.

  2. Rob in Maine says:

    > somewhat akin to a nuclear bomb?

    More like when you start your gas grill and it takes a few “clicks” of the igniter. “PHOOOMF!”

    Like that, but unimaginably big.

  3. AnAmericanMother says:

    Old arson investigators like myself have always looked at the contracted limbs of most of the Pompeii victims and thought, “Hmmm. That was quick.”

    This confirms it.

    I’d like to see a comparison with the deaths at Herculaneum. There wasn’t much ash deposit there, so there aren’t the lifelike casts that you see at Pompeii, but there’s plenty of evidence of pyroclastic flows. For a long time it was thought that most of the inhabitants of Herculaneum had escaped, but apparently they just had a little more time to flee or take refuge.

  4. Philangelus says:

    It’s all so fragile. Our lives are so fragile. :-(

  5. Andrew says:

    I always laugh to myself when I read the account of these events by Plinius, in his letters (book 6,20) where he says that the roofs were already collapsing and burning stones were raining down while he asked for some reading material and started to read Livius and also to take notes until some relative of his came and reprehended him and so he got up and left together with his mother through a dark cloud that turned the day into night. These Romans were something else. You’ve got to admire their spirit. I also think of his uncle, Pliny the Elder, (a favorite author of St. Francis de Sales) who went up to the mountain to see the volcanic activity for himself, while everyone else was fleeing.

  6. Traductora says:

    It would have been a long 30 seconds, although I would imagine there wasn’t much oxygen in the air at that point so perhaps it might have been less. If anybody feels like a bit of good historical fiction (I know, much enhanced and achronic, with bits of blurry focus), Robert Harriss’ Pompeii is very good. It’s about an engineer on the Roman aqueducts who knows that something seriously bad is beginning to happen with Vesuvius…

  7. MarkJ says:

    Fire and Ice

    Some say the world will end in fire,
    Some say in ice.
    From what I’ve tasted of desire
    I hold with those who favor fire.
    But if it had to perish twice,
    I think I know enough of hate
    To say that for destruction ice
    Is also great
    And would suffice.

    by Robert Frost

  8. Supertradmum says:

    If I remember correctly, Pliny the Elder died on the seashore. He was in charge of the fleet and refugees.

    Ah, here it is http://www.eyewitnesstohistory.com/pompeii.htm

  9. TJerome says:

    My understanding is that only 10% of the population died. 90% got out.

  10. AnAmericanMother says:

    TJerome,

    That was the traditional view, back when I was studying Classical Archaeology in college. It was thought that most of the population of Herculaneum escaped, while more died at Pompeii.

    But recent discoveries have changed that view. I think it was about 10 years ago — there was an article in Smithsonian about renewed excavations at Herculaneum (they have gone very slowly because a modern town was built right over it and land acquisition is problematic). They discovered several large groups of skeletons in arched structures near the old harbor – warehouses or cellars. Apparently people fled there for refuge or to take ship, but never got any further (as Pliny says, the wind was wrong).

  11. Sedgwick says:

    Contrast this with freedom and religious liberty in the United States, which is dying very slowly and very surely, due to a satanic perversion of “compassion”:

    http://www.lifesitenews.com/ldn/2010/jun/10062806.html

  12. AnAmericanMother says:

    Oh, and something I forgot until this moment — during the excavations of Herculaneum, a strange mark on the wall was found above what looks like a prie-dieu (in Herculaneum all the bodies were reduced to bones, but furniture and even food was carbonized, sealed and preserved by the lava flows).

    Theory is that a cross or crucifix was affixed to the wall there, and the householder pulled it from the wall and took it with him as he fled.

    The Herculaneum Cross — unfortunately one of those abstracts of a subscriber-only service, but it gives you the basic facts. The cross was also mentioned in a book I read for one of my Archaeology courses. There’s a picture here in an old Life magazine in Google books. Top right of the page.

  13. Sam Schmitt says:

    Where is everybody running to?