Researchers from the University of Leicester’s Department of Geology’s Volcanology Group have collaborated with the University of California Santa Cruz, Idaho State University and the University of Copenhagen to study volcanic activity along what is known as the Yellowstone hotspot-track. One of those super events, called the Castleford Crossing eruption, occurred approximately 8.1 million years ago and is estimated to have had a volume of more than 1,900 km3. For comparison, the eruption that created the Yellowstone caldera, ejected more than 1000 km3.
This is only one of 12 gigantic eruptions in the area of the central Snake River Plain that the team reported. They greatly reduced the number of eruptions thought to have originated in the area, but determined that the events were of much greater magnitude than previously thought, and may rival the well-known eruptions at Yellowstone.
Dr. Tom Knott said in Phys.org: “While it is well-know that Yellowstone has erupted catastrophically in recent times perhaps less widely appreciated is that these were just the latest in a protracted history of numerous catastrophic super-eruptions that have burned a track along the Snake River eastwards from Oregon to Yellowstone from 16 Ma to present. The size and magnitude of this newly defined eruption is as large, if not larger, than better known eruptions at Yellowstone, and it is just the first in an emerging record of newly discovered super-eruptions during a period of intense magmatic activity between 8 and 12 million years ago.”
It is common knowledge that massive eruptions occurred in the Yellowstone region, resulting in the geysers and hot springs of the national park. Yellowstone itself sits above a magma plume and massive caldera. The caldera is actually a “hot spot” of magma that travels beneath the U.S. as Earth’s plates shift. Scientists have long held that Yellowstone produced some of the most massive eruptions of the past.
The new research has led scientists to believe they have discovered the true volcanic history of the region. The team used a multi-technique approach that included paleomagnetic data, whole-rock and mineral chemistries and radio-isotopic dates to “fingerprint” deposits from individual eruptions. They were then able to correlate these over large regions.
During this correlation the number of eruptions originally thought to have originated from the Snake River Plain was reduced by more than half. Researchers say their findings illustrate how varied the volcanic history of Yellowstone really is.