Wednesday, December 11, 2019

Update on the Volcanic Eruption on White Island

On Monday of this week, a volcano off the coast of New Zealand erupted while tourists were on the island. Initial reports were 18 confirmed injuries, 5 confirmed dead, and 20 missing and presumed to be dead. Fortunately, those early estimates overstated the disaster a bit. Latest reports indicate 8 dead (2 of which succumbed to their wounds after being evacuated to a hospital), 9 missing, and 28 hospitalized. Another article indicates that because many of the injured suffered severe burns over large portions of their bodies, New Zealand has ordered 143 square yards (1.2 million sq cm) of skin from America to use in skin graft operations. From that article:
       A total of 29 patients have been admitted to hospital with burns in the wake of Monday's deadly eruption, and doctors say they urgently need more skin grafts. 

      Faced with an unprecedented number of burn victims and the unusual nature of the burns from toxic volcanic gases, surgeons are having to work quicker than usual. 

       It is predicted surgeons have 500 hours of operations to perform on patients in the days and months ahead of them. 

      Officials say 34 people were rescued from White Island via helicopters and admitted to hospitals for their injuries. Of the 29 with burn injuries, 27 have burns over at least 30 per cent of their bodies. 

     22 of the victims had inhalation burns after breathing in sulphur dioxide and volcanic ash that have affected their lungs, and have been left requiring airway support.

     Several of the patients have burns affecting up to 95 per cent of their bodies. 
Another article details how an American couple, although suffering significant burns, survived by hiding behind a boulder. One of the victim's mother related:
      '(Matthew) told me they had already come down from the volcano when it started to erupt.

      'They were able to take some shelter behind a large rock, 10 minutes it could have meant life or death for them, but luckily they were already down the volcano close to the water, so they sheltered themselves a little bit. 
     'They already had been provided with respirators so they didn't breathe in all the ash.'

     She added: 'I spoke with (Matthew) this morning. He'd just had surgery last night, about a three-hour surgery. The burns were a little worse than we had hoped, and he's going to need skin graphs and plastic surgery.

      'He'll have a repeat surgery in 48 hours, but he was able to talk to me, he's taking fluids and eating a little jello, so stable for now.' 
    One source indicated that "[t]he explosion was likely phreatic in nature (steam-driven); it generated an ash plume that rose to approx. 12,000 ft (3600 m) as well as a pyroclastic flow that reached the sea, as parts of the eruption column collapsed." (See also, "Whakaari / White Island eruption: What scientists say about the volcano" and "When Volcanoes Attack… White Island Edition"). Volcanic gases can include carbon dioxide, sulfur dioxide, hydrogen sulfide, and various poisonous and acidic hydrogen halides that, when dissolved in water (e.g., steam), can form compounds such as hydrochloric acid and hydrofluoric acid. As for pyroclastic flows, the USGS explains:
Pyroclastic flows contain a high-density mix of hot lava blocks, pumice, ash and volcanic gas. They move at very high speed down volcanic slopes, typically following valleys. Most pyroclastic flows consist of two parts: a lower (basal) flow of coarse fragments that moves along the ground, and a turbulent cloud of ash that rises above the basal flow. Ash may fall from this cloud over a wide area downwind from the pyroclastic flow.
Pyroclastic flows generally travel at 50 mph but have been recorded moving as fast as 450 mph, and the temperatures of gases and rocks will generally be between 390-1300°F. A Forbes article on the topic of how pyroclastic flows kill describes:
      Assuming you’re on the ground, you’ll first encounter the intense heat riding at the front of the flow. If it’s a surge, despite it being cooler than a flow, you will still combust; your skin will rupture and becoming blackened by the severe heat of the gas before most of the ash even touches you microseconds later.

       Even hiding inside a building won’t save you. When a surge passes by, the temperature of the air in the environment around it can sometimes be about 300°C (570°F), enough to destroy anything living within mere moments, and certainly high enough to severely damage the linings of your lungs if you breathe any of this heated gas in. If it does hit you, any fabric you have on will quickly burn away, and if you’re wearing any metal, it’ll sear itself into your skin for as long as it is still intact.

      A flow isn’t much better, as you’ll be sautéed as soon as the flow front hits you. In both cases, your muscles will suddenly contract, and you’ll curl up into something resembling a pugilistic pose. The ash and gas will rush into your airways and, if you had time to live after the extreme heat shock, you’d quickly asphyxiate.

      Some of the famous Vesuvian victims in Herculaneum were found with their skulls blown apart. It appears that the heat of the surge was so extreme that their brains boiled, releasing trapped gases so quickly that it blew apart their heads.

      Either way, all that would be left of you would be a charred skeleton – if you’re lucky.
      Although volcanic ash (tephra) is not, by itself, immediately lethal. However:
Ash fallout to the ground can pose significant disruption and damage to buildings, transportation, water and wastewater, power supply, communications equipment, agriculture, and primary production leading to potentially substantial societal impacts and costs, even at thicknesses of only a few millimetres or inches. Additionally, fine grained ash, when ingested can cause health impacts to humans and animals.
 As for surviving a volcanic explosion, there isn't a whole lot that you can do other than not be there: the rest is mostly luck. Although you might think moving to high ground would work, because the flow is driven by heated air, it can actually rise as it dumps heavier material and because less dense. Getting to a shoreline may not help either because the flows can extend out over water. The couple that survived this incident survived because they already had filters through which to breath, and the boulder behind which they hid probably blocked the force of the blast. Nevertheless, the heat caused wide spread burns. They were in a location where they could quickly be helicoptered to a hospital able to treat their injuries. If circumstances were different, they might have died from their burns or secondary infections.

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