The Yellowstone Caldera, a volcanically active region under and around Yellowstone National Park, has long been the subject of research, speculation and science fiction regarding the possibility of a volcanic eruption.
But a new study shows that such an event may be even less likely than we thought: Scientists have discovered a magma cap that may play a role in releasing pressure that contributes to large eruptions.
Scripps News spoke with Michael Poland, the scientist in charge of the Yellowstone Volcano Observatory, for more insight into the new findings and how they affect Yellowstone.
Scientists "were bouncing earthquake waves off of the top of the magma chamber," Poland said. "And that can tell you something about the characteristics of the top. And they found the top was full of bubbles. Now on the surface that might seem more concerning because those bubbles might indicate that pressure could be increasing. But the key was they didn't find that many bubbles. And in fact, the gases that are coming out of Yellowstone that we can measure at places like Old Faithful and Mud Volcano. Those have magmatic composition. So the whole system together seems to be very efficiently moving these bubbles up to the surface. So no pressure is actually building. This cap is sort of allowing bubbles to accumulate and then get transferred up to the surface."
"I think the real take-home message is that we could even see this in the first place," Poland said. "I mean, this is incredible that we have the resolution now to be able to use seismic imaging techniques. It's sort of like taking an MRI of the Earth. And we can see this few hundred foot thick cap to the Yellowstone magma reservoir that's over 2 miles deep. I think that says a lot about our ability to see into the Earth. This same technique, now that it's been tested out in a place like Yellowstone, might be applied in other places. And it could potentially tell us whether or not we might expect eruptions in other locations."
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In the meantime, Poland says, Yellowstone is not likely to generate a massive volcanic explosion like those seen in fictional movies.
"The vast majority of eruptions at Yellowstone are lava flows," Poland said. "If you're standing at Old Faithful and you look all the way around, you can see sort of high topography, cliffs and hills. Those are all lava flows that erupted since the last really massive explosion at Yellowstone."
But "even that isn't that common. The last lava flow erupted about 70,000 years ago. Far more common on human timescales in the region are hydrothermal explosions, those sort of really, really energetic geyser eruptions that can throw rocks."
Watch the full interview with Poland in the video above.