The Yellowstone volcano is one of the few dozen volcanoes on Earth labelled a supervolcano for its ability to expel more than 250 cubic miles of ash and debris. The plumes from such eruptions can rise 17 to 30 miles into the atmosphere, above the cruise-level of jets and can cause devastation on a global level. This type of event has occurred three times in history: 2.1 million years ago, 1.3 million years ago and 630,000 years ago.
Larry Mastin, a USGS Hydrologist, worked with fellow colleague Jacob Lowenstern in 2016 to produce a paper on the ash-fall impacts in the event of another supereruption.
Speaking during a public lecture the same year, he explained: “The objective was to see how the growth of umbrella clouds would affect ash distribution from Yellowstone.
“We did a few dozen simulations starting with an erupted volume of a few hundred cubic kilometres of magma.
“So this is – if you consider the volume of tephra that expands as it erupts – the volume of the tephra blanket that forms would be a few times greater than that of the magma alone.
So in these simulations you can see, that over a three-day period, this umbrella cloud covers most of the North American continent
Larry Mastin
“So this would be comparable to a tephra volume over 1,000 cubic kilometres.
“We used a duration that ranged from three days to one month and an umbrella cloud height that ranged from about 15 to 35 kilometres (nine to 18 miles).
“The wind fields were randomly chosen from historical patterns, but turns out they are actually not that important.”
Mr Mastin then demonstrated how a Yellowstone supereruption would bury the majority of North America in ash, with some regions more heavily affected.
He detailed how the duration of the eruption, or the time of year seemed to make little change on its consequences.
He added: “So in these simulations you can see, that over a three-day period, this umbrella cloud covers most of the North American continent.
“Then it gradually disperses with wind patterns, so you can look at the tephra deposit in these four different three-day simulations.
“One in January, one in April, one in July and once in October, the pale yellow is one to three millimetres, three to 10, 10 to 30, 30 to 100,100 to 300 and the dark regions are over a metre of ash.
“if you go to a one-week duration, the pattern looks pretty similar and for one month it is fairly the same.
“But as you go to one month, we’re decreasing the average eruption rate, which is weakening the growth of the umbrella cloud.”
It comes after it was previously revealed how parts of Yellowstone National Park were closed after recording an uplift in the caldera.
In 2003, changes at the Norris Geyser Basin resulted in the temporary closure of some trails in the basin.
New fumaroles were observed, and several geysers showed enhanced activity and increasing water temperatures.
Mr Lowenstern, who was tasked with monitoring the activity for the USGS, revealed during a lecture at Menlo Park, California, why the park was closed.
He said in 2014: “Around that time there was a lot of hydrothermal activity in the Norris Geyser Basin area and a new linear vent that formed at Nymph Lake.
“It formed some really loud jet-like thermal features and a lot of trees died in the area in that time and park geologists spent quite a bit of time documenting the changes.
“Later that summer there was a whole region in the Norris Geyser Basin – the Back Basin – where there was anomalous activity in a lot of the geysers and the ground temperature was increasing greatly and a lot of pools that were turning into steam vents or fumaroles.
“Here’s an example of a thermal image taken on one of the trails, you can see some of the temperatures are hitting above 50C, but some reached the boiling point of water.
“If you were walking barefoot, you would have been pretty uncomfortable, so the Park Service closed off the Back Basin for a period of about a month and things cooled off and went back to normal.”
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