Yellowstone supervolcano contains twice as much melted rock as thought

There is extra melted rock beneath Yellowstone Caldera – a volcano in Wyoming – than was beforehand estimated, however that doesn’t change the probability of an eruption

By James Dinneen

The magma reservoir beneath the Yellowstone Caldera incorporates nearly twice as a lot melted rock as beforehand thought. The elevated estimate, nonetheless, doesn’t meet the edge that means an eruption at Yellowstone is extra possible.

The Yellowstone Caldera in north-western Wyoming is likely one of the largest volcanoes on this planet. In the previous 2.1 million years, it has seen three catastrophic eruptions that blanketed North America in ash and numerous smaller eruptions the place lava flowed throughout the caldera, most lately 70,000 years in the past. Researchers intently monitor Yellowstone for any adjustments that might sign an eruption, akin to floor deformation or earthquakes.

Eruptions are provided with magma from two big reservoirs beneath the caldera, one close to the mantle and one just a few kilometres beneath the floor. Once considered merely as “big tanks” of magma, the reservoirs comprise a posh “crystal mush” of melted rock and crystals, says Ross Maguire on the University of Illinois Urbana-Champaign. The composition of this mush partly determines the volcano’s probability of erupting: a better proportion of melted rock to strong crystals makes the magma extra prone to mobilise.

Because seismic waves transfer extra slowly by way of areas with extra melted rock, Maguire and his colleagues have been in a position to analyse seismic information recorded round Yellowstone over the previous 20 years to estimate the proportion of melted rock within the shallower magma reservoir.

Where previous analyses used a easy mannequin that handled the waves as linear rays, their evaluation used supercomputers to mannequin the waves in three dimensions to get a extra full view of the reservoir.

They discovered the reservoir consists of 16 to twenty per cent melted rock on common – in contrast with a earlier estimate of about 9 per cent – relying on assumptions made concerning the form of areas between strong crystals. That suggests the reservoir incorporates about 1600 cubic kilometres of melted rock, or nearly twice as a lot because the earlier estimate of roughly 900 cubic kilometres.

Even on the excessive finish of their estimate, Maguire says the proportion of melted rock remains to be properly beneath the 35 to 50 per cent threshold wanted for an eruption. “Yellowstone can spend large amounts of its life cycle with some melt without eruption,” he says.

Kari Cooper on the University of California, Davis, who wrote a commentary on the analysis, says, relying on how the melted rock is distributed, there could possibly be sufficient for a small eruption, however this work reveals there’s undoubtedly not sufficient there for a catastrophic eruption.

“It’s a big improvement in our ability to understand what’s beneath Yellowstone,” says Cooper.

Journal reference: Science, DOI: 10.1126/science.ade0347