June 2010 just ended, so it’s time for the PLoS ONE Blog Pick Of The Month.
Greg Laden of the eponymous blog, for his post How did the victims of the Plinean Eruption of Vesuvius die? describing and explaining the research in the PLoS ONE article Lethal Thermal Impact at Periphery of Pyroclastic Surges: Evidences at Pompeii by Giuseppe Mastrolorenzo, Pierpaolo Petrone, Lucia Pappalardo and Fabio M. Guarino of Napoli, Italy. The paper’s Abstract states:
The evaluation of mortality of pyroclastic surges and flows (PDCs) produced by explosive eruptions is a major goal in risk assessment and mitigation, particularly in distal reaches of flows that are often heavily urbanized. Pompeii and the nearby archaeological sites preserve the most complete set of evidence of the 79 AD catastrophic eruption recording its effects on structures and people.
Here we investigate the causes of mortality in PDCs at Pompeii and surroundings on the bases of a multidisciplinary volcanological and bio-anthropological study. Field and laboratory study of the eruption products and victims merged with numerical simulations and experiments indicate that heat was the main cause of death of people, heretofore supposed to have died by ash suffocation. Our results show that exposure to at least 250°C hot surges at a distance of 10 kilometres from the vent was sufficient to cause instant death, even if people were sheltered within buildings. Despite the fact that impact force and exposure time to dusty gas declined toward PDCs periphery up to the survival conditions, lethal temperatures were maintained up to the PDCs extreme depositional limits.
This evidence indicates that the risk in flow marginal zones could be underestimated by simply assuming that very thin distal deposits, resulting from PDCs with poor total particle load, correspond to negligible effects. Therefore our findings are essential for hazard plans development and for actions aimed to risk mitigation at Vesuvius and other explosive volcanoes.
In his blog post, Greg Laden writes:
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.
Oh, and there is a video!
March 2009: Ed Yong
April 2009: Eric Michael Johnson
May 2009: Christie Wilcox
June 2009: Iddo Friedberg
July 2009: Toaster Sunshine and Hermitage
August 2009: Bjoern Brembs
September 2009: Alun Salt
October 2009: Andrew Farke
November 2009: John Beetham
December 2009: SciCurious
January 2010: Anne-Marie Hodge
February 2010: Princess Ojiaku
March 2010: Grrrlscientist
April 2010: Jason Goldman
May 2010: Brian Switek