Apocalypse not now
Parkgoers can put off panic over eruption for a few ages
YELLOWSTONE NATIONAL PARK, Wyo. – You can’t miss the heat coming from beneath the surface. It’s visible everywhere you look, from the steaming geysers to the bubbling mud puddles and the colorful hot springs. All that activity is fueled by a smoldering supervolcano, a heat engine buried deep underground that has produced some of the largest eruptions in the world. The last supereruption about 631,000 years ago spewed 240 cubic miles of pulverized rock and ash into the atmosphere, covering nearly half the country in the powdery residue.
“It’s an active volcano. It will erupt again,” said Michael Poland, scientist-in-charge at the Yellowstone Volcano Observatory, a consortium of eight organizations led by the U.S. Geological Survey.
But don’t go changing your vacation plans just yet – or potentially ever.
Scientists who study Yellowstone’s 45-by-30-mile caldera, roughly the size of Rhode Island, say the un-
derground system probably will give decades of warning before it blows – and that isn’t likely to happen for thousands of years. Despite the seismic orchestra of “snap, crackle and pop” that goes on underground, there are no signs it’s about to become more explosive.
“Geological events are stunning in their power, but they’re infrequent in human terms,” said Jerry Fairley, a professor of geological sciences at the University of Idaho who has studied Yellowstone’s supervolcano for the past nine years. “We live on a very active planet, but it’s rare that we get to see the kind of power from the Earth that it is capable of generating.”
‘It’s the story that never dies’
That long view has been partially drowned out in the past decade by a fever pitch of documentaries, online articles and amateur video clips that point to Yellowstone’s frequent minor earthquakes – it averages 1,500 to 2,500 a year – or blatantly false rumors that the ground is swelling upward as signs the volcano’s time bomb is ticking down. The result, the most extreme of these conspiracy theories say, would be the end of the world.
Such warnings draw conclusions from the volcano’s past eruptions to model what it could spew next – a faulty connecting of dots that ignores key information on how volcanoes operate, experts say.
The park service fields calls every year from would-be vacationers who want to know if visiting the national park, which receives more than 4 million people a year, would put them in danger. “We see people who are thinking about changing their plans because of the stuff they’re reading,” said Neal Herbert, a spokesman for the park. “It’s the story that never dies.”
Heavy summer crowds feel the steam coming off the geysers and see the brilliant colors of the hot springs – shades of burnt orange, bright blue and vivid green – created by the microorganisms that thrive in the extreme heat. Regular earthquakes are usually too subtle, at magnitude 2 or far less, to jolt them.
Those rumblings are one of the giveaways a giant volcano slumbers below the surface. The frequent quakes may act as a safety valve to release pressure before it builds up, similar to how a pressure cooker releases steam so it remains safe. “They may be a sign of safety rather than a sign of impending doom,” Fairley said.
Warning signs would occur well before an eruption. Multiple, large earthquakes would rattle the park; the ground would move up or down by tens of feet over months or years as the magma underneath shuffled around; gases would be emitted from the ground; the chemicals in the springs would change; and more heat would be generated, Poland said.
It’s simply business as usual for the park right now, Fairley said. “Yellowstone, in a sense, is breathing,” he said.
An eruption would probably be on a smaller scale that more closely resembled Hawaii’s Kilauea volcano this summer, which caused a lava flow that forced evacuations and submerged neighborhoods but didn’t result in the cataclysmic destruction of Yellowstone’s past super eruptions. The last time Yellowstone experienced a lava flow was about 70,000 years ago.
We’d probably have decades of warn- ing between the first sign of an eruption and Yellowstone actually blowing its top, said Christy Till, a geologist and assistant professor at Arizona State University who has researched the volcano for the past six years.
The magma underneath Yellowstone would need to be heated up – a lot: Seismic studies indicate it’s mostly solidified, not the hot liquid required for an eruption.
“You would need to collect a huge volume of magma all in the same place, and then you’d need to generate enough pressure to get it moving up to the surface,” Poland said. “And we see neither of those conditions in place right now.”
It’s entirely possible those conditions may never exist again: The supervolcano may be dying, said Ilya Bindeman, a University of Oregon geology professor who has worked on Yellowstone’s caldera for 20 years. Each supereruption melts part of the crust, hardening it and making it more difficult to generate enough heat to remelt the material.
The heat below can’t break through the tough outer skin formed by previous eruptions.
‘It would not be a fun time’
If the worst-case scenario did hap- pen, it wouldn’t be a pretty day – for decades – in the USA.
“The eruption of Mount St. Helens would be a small firecracker compared to one of the major caldera eruptions of Yellowstone,” Fairley said.
Millions of people would die in the immediate explosion and in its aftereffects, Fairley predicted. Ash would fall over much of the country, grinding air traffic to a halt. Water would be contaminated, livestock would die, crops would fail and the country’s heartland would be unfarmable for years. The climate would change because ash would filter out the sun’s powerful rays, and it would be several years or even decades before it could bounce back.
During Yellowstone’s supereruption about 631,000 years ago, ash covered North Dakota through most of Texas and from Southern California through most of Missouri and Arkansas.
But a massive eruption at Yellowstone would still not be the mass-extinction-level event some fear. “Humanity would survive, but it would not be a fun time,” Poland said.
Humanity has actually done just that – we were around for two such eruptions in the past 100,000 years, both even larger than the last big one at Yellowstone.
Grand Prismatic Spring is one of Yellowstone National Park’s main attractions.
Old Faithful erupts Aug. 4 in Yellowstone National Park. The geyser got its name because viewers can count on it to put on its show about every 90 minutes.