At least a meter of ash would blanket parts of the Rocky Mountain range and a few millimeters of the fallout would reach cities on both coasts of the U.S. if the Yellowstone supervolcano erupted, according to new computer simulation on the event, something that's unlikely to happen anytime soon.
There have been no supereruptions in recorded history that would size up with an explosion spewed by the Yellowstone supervolcano. Even eruptions by Chile's Quizapu volcano and the Valley of Ten Thousand Smokes in Alaska are magnitudes below a Yellowstone event, according to the simulation on a Yellowstone eruption and the model's accompanying study.
The Ash3D model simulated Yellowstone's eruption and the study, "Modeling ash fall distribution from a Yellowstone supereruption," was published in the Wiley Online Library.
There has been a rise in demand for models projecting the density of the ash driven by a ground-collapsing eruption from the Yellowstone volcano, according to Larry Mastin, lead author of the study. Mastin is also a U.S. Geological Survey hydrologist and he helped develop the Ash3D model.
"It's a crazy thing to think about because none of us have ever seen an eruption like Yellowstone," said Mastin. "It would be two or three orders of magnitude more ash than we've been able to observe."
Yellowstone's most recent caldera eruption, a crater-forming event, occurred roughly 640,000 years ago and, despite occurring in 600,000 to 800,000 intervals, geologists have indicated that there's no evidence the supervolcano is preparing for another cataclysmic explosion -- disregard the herds.
With evidence affected by hundreds and thousands of years of erosion and seemingly dormant volcanos awaking with little notice, the study using the Ash3D model is an act of prudence. After simulating a modern-day Yellowstone eruption, researchers determine that, unlike the fan-like plumes of smaller volcanoes, a Yellowstone caldera eruption would release an "umbrella" (PDF) of ash that would spread from the center of the U.S. and reach to both shores.
"In essence, the eruption makes its own winds that can overcome the prevailing westerlies, which normally dominate weather patterns in the United States," said Mastin. "This helps explain the distribution from large Yellowstone eruptions of the past, where considerable amounts of ash reached the West Coast."
The effects of the supervolcano's ash cloud would have a significant impact on every part of the U.S., even regions where only millimeter or two of the soot rained down. The whole continent would suffer drastic change.
"Electronic communications and air transportation would likely be shut down throughout North America," stated the study (PDF). "There would also be major climate effects. Emission of sulfur aerosols during the 1991 Pinatubo eruption produced global cooling by an average of 1 degrees Celsius for a few years, while the 50-km 3 Tambora eruption of 1815 cooled the planet enough to produce the famed 'year without a summer' in 1816, during which snow fell in June in eastern North America and crop failures led to the worst famine of the 19th century."