[ad_1]
The Yellowstone Caldera is a supervolcan located south of Yellowstone National Park in the western United States. It lies between the states of Wyoming, Montana and Idaho and is continuously monitored by the US Geological Survey (USGS) because of its ability to inflict a disaster on a global scale in case of supereruption. The last event of this type has not occurred for more than 630 000 years and no serious eruption on 70 000 – which would have resulted in another expected super-eruption.
Larry Mastin, a USGS hydrologist, worked with his colleague, Jacob Lowenstern, in 2016, to produce a paper on the impacts of ash fall in the event of a new super-eruption.
Speaking at a conference the same year, Dr. Mastin revealed how USGS scientists had recorded three previous eruptions in Yellowstone that they could use to predict future incidents. .
He said: "Three major events have been identified in Yellowstone over the last two million years.
"The most important of them was Huckleberry Ridge, 2.1 million years ago, representing a volume of about 2,500 cubic meters of magma.
"Then Mesa Falls, 1.3 million years ago, and Lava Creek – the second of two Lava Creek eruptions around 600,000 years ago.
"These are therefore volumes estimated only from these deposits and that do not include the tephra-fall deposits that may have been transported over more than 1,000 km (620 miles).
"The duration of these rashes is not really limited, but experts tend to think that they may have lasted a few days – very quickly – a few days or even weeks at most."
Mr. Mastin then revealed how the results of the Huckleberry Ridge eruption proved that Yellowstone had the power to send ash deposits to the United States, up to California, about 1,000 miles.
He also explained that the wind structure seemed to have little impact, making it even more difficult to predict future events.
He continued: "These eruptions actually produced tephra falls – in other words, deposits were produced by the tephra and rose in a floating manner, drifting in the wind during these eruptions.
"We know it from the deposits scattered around the United States.
"But in reality, on a more recent map of these deposits, we could find them as far west as California, Oregon and even offshore.
"So it adds a real headache because it is clearly upwind of Yellowstone.
"Even if you look at the wind patterns that may have existed over the last million years, it seems unlikely that the wind regime has changed significantly to send ash deposits as far back as possible. Where is."
Dr. Mastin also discussed at the same conference impacts on the duration of an eruption, should Yellowstone be triggered again.
He added: "Over a period of three days, the umbrella cloud [would] cover most of the North American continent.
"Then, the wind gradually disperses, 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 1 to 3 millimeters, 3 to 10, 10 to 30, 30 to 100 100 and 300 and the dark regions are more one meter of ashes.
"If you opt for a duration of one week, the pattern looks pretty similar and for a month it is pretty much the same.
"But after a month, we reduce the average blowout rate, which weakens the growth of the general cloud."
[ad_2]
Source link