A team of geologists from the U.S. Geological Survey, working with a trio of colleagues from Oregon State University and another from the University of Wisconsin-Madison, found evidence of rhyolitic volcanism in the caldera of Yellowstone moving northeast.
In their paper published in the journal Nature, the group describes how they used an electromagnetic geophysical method to study the soil beneath the Yellowstone caldera.
The Yellowstone Caldera is a volcanic caldera and supervolcano in Yellowstone National Park, located in the western United States – it has sometimes been called the Yellowstone Supervolcano due to its massive size. it is one of the largest on planet Earth.
Previous research has shown that the supervolcano has experienced three major caldera-forming eruptions in the last 2.1 million years, with the most recent lava flow dating back about 70,000 years. It is unclear when it might erupt again.
In this new study, researchers investigated the composition of the material beneath the caldera, which is part of a broader effort to better understand volcanic eruptions to help predict when they might occur.
Previous efforts to obtain an accurate estimate of the type and amount of material beneath the Yellowstone caldera have led to mixed results due to the extreme conditions. The research team took a new approach: they carried out a major magnetotelluric study across the entire caldera. Such an approach involved measuring electromagnetic geophysical properties that account for variations in the Earth’s magnetic field, which also made it possible to infer the conductivity structure of the crust.
The survey allowed researchers to see that there are seven, and perhaps more, unique regions of magma residing beneath the caldera, some feeding others, at depths ranging from 4 to 47 kilometers, near the boundary of the coat.
The research team also noted that the most interesting melt storage reservoirs were located in the northeastern parts of the caldera, suggesting that they were likely to be most active in the future. The reservoirs, they found, contain basaltic magma in their lower parts and rhyolitic magma in their upper parts.
The team was even able to make estimates regarding the quantities – they discovered that there was a melt storage of approximately 388 to 489 cubic kilometers. A much higher amount than in the south, west and north, where previous eruptions had been centered.
