Brigham Young University geologists Eric Christiansen and professor emeritus Myron Best have uncovered evidence of 17 supervolcanoes in southern Utah and Nevada.
These supervolcanoes erupted nearly 30 million years ago during a one-week period. They are believed to be among the largest volcanic eruptions in the earth’s history.
“A supervolcano is a hole in the ground called a caldera,” Best explained. “When a very large volume of magma erupts explosively in a single geological event, it can create a depression.”
Found along the Wah Wah Springs Tuff in southwestern Utah, this massive caldera spewed more than 250 cubic miles of magma, known as a supereruption, affecting a region extending from central Utah to central Nevada. Today the area is a flat, desert-like plateau, which has helped hide the caldera from the naked eye for thousands of years.
“The ravages of erosion and later deformation have largely erased them from the landscape, but our careful work has revealed their details,” Christiansen said. “The sheer magnitude of this required years of work and involvement of dozens of students in putting this story together.”
The extensive work done to uncover these supervolcanoes can be attributed to a core group of six researchers, with the help of hundreds of undergraduate and graduate students, during a 30-year period.
Kim Sullivan, a former student who was involved in the project, recalls, “I just happened across evidence of the rim of an ancient caldera while mapping a small area as a young field camp student.”
This team worked together collecting samples and then performing a series of chemical analysis, magnetic analysis and radiometric dating that helped put the pieces together.
According to their findings, ash fell over about half of the continent, which would have killed any plant or animal life in the area. The volcanoes erupted enough ash to have blocked out sunlight for a period of time, causing a dip in the global temperature.
Best explained that 30 million years ago large mammals, including camels, bison, rhinoceroses, horses and tortoises, roamed this region. The research team found as much as 15,000 feet of ash near the caldera, meaning that everything in the area would have been killed instantly and buried under the thick deposit.
The volcanoes are no longer active due to the change in the current tectonic arrangement along western North America.