Scientists have devised a new way to estimate how fast magma is "recharging" beneath the Yellowstone supervolcano, according to a new study published in the journal Geosphere.
The technique, which was developed by a team from Washington State University (WSU) and the University of Idaho, will enable researchers to better understand the pools of magma (molten volcanic rock beneath the Earth’s surface) that recharge the system, although it won’t necessarily help to predict when the volcano will erupt.
“It is the coal in the furnace that’s heating things up,” Peter Larson, a professor at the WSU School of the Environment, said in a statement. “It’s heating up the boiler. The boiler is what explodes. This tells us what is heating the boiler.”
Yellowstone’s last major eruption took place around 640,000 years ago, producing a blast that ejected more than 2,000 times the amount of ash spewed out by Mount St. Helens in 1980.
When Yellowstone does erupt, much of its destructive power will come from a type of silica-rich volcanic rock, known as rhyolite, which breaks through the Earth’s crust and is ejected by the volcano. During their study, the researchers looked at plumes of basalt magma which were heating the rhyolite from below.
“This gives us an idea of how much magma is recharging the volcano every year,” Larson said.
To make their findings, the researchers “spiked” several hot springs in Yellowstone National Park with deuterium—a form of hydrogen. These hot springs are part of a vast hydrothermal system which is intrinsically linked to the Yellowstone volcanic system.
Using the temperature of the hot springs and the length of time it took for concentrations of deuterium to return to normal background levels, the scientists calculated the amount of water and heat flowing through the springs.
They found that the quantities of water flowing through them and the amount of heat leaving them was higher than previous studies have shown. This new data enabled the team to estimate the amount of magma entering the supervolcano from the Earth’s mantle—the layer below the crust.
The results of the study could also have implications for generating power using geothermal energy, enabling scientists to better understand how heat is transferred to the Earth’s surface by molten rock.