SETTING THE YELLOWSTONE TRAP
Yellowstone breathes. The national park rises and falls as one’s chest expands and contracts as lungs inflate and deflate. The land ever so slowly bows upward for a decade or two, then the surface relaxes and falls as internal pressures three, four, and more miles below decrease.
It’s a living thing, Yellowstone is, or so it seems. It’s hot blooded, anyway, its circulatory system charged with scalding hot water brought to a boil or flashed to steam by a heart of volcanic magma no farther distance from the surface than a drive to a convenience store to fetch a carton of milk.
As I write this, Yellowstone is rumbling. Over the past month or two, low-level earthquake swarms have skittered through the geology of the Earth’s largest volcanic structure. In reality, Yellowstone is never seismically quiet, but of late the pace of seismicity has evolved into a cantor. When that happens, geologists begin to pay close attention to the slumbering beast at home in the northwest corner of Wyoming.
The 1,500-square-mile caldera that makes up a fair extent of the landscape of the national park is a scar sitting atop one of just a few ‘hot spots’ on Earth that rise from the planet’s mantle and all the way through the crust. Hot spots are direct conduits to the surface from deep within the body of our heavenly home. Liquid rock can rise and fall within the internal plumbing of these cryptic geological features. At Yellowstone, the filling and draining of the huge magma reservoir a few miles down is what causes the terrain to expand and contract as if Yellowstone were drawing a breath and exhaling it.
That geological scar on the surface that is Yellowstone is actually a healed wound that runs some 400 miles in length, from eastern Washington State, through Idaho to, now, Wyoming. The entire Snake River Valley is a crusted over knife slash created by staggeringly large eruption events that spewed from the Yellowstone hotspot. As the North American continent drifts southwestward at the rate our fingernails grow, the landscape of the West slides directly over the barrel of Yellowstone’s geological pistol. On a cycle of 600,000 years or so (give or take 100,000), the Earth suddenly pulls the trigger and the ensuing shot cripples the continent and affects climate dramatically all over the globe. The Snake River Valley is rock solid evidence of the power of repeated catastrophic eruptions that have been rototilling the Rocky Mountains for 15-million years.
In Royal Nebraska, on the flat northeastern flank of the state, there is a museum known as Ashfall Fossil Beds State Historic Park. A vast structure in the prairie houses the skeletal remains of scores of huge rhinoceros-like animals called teloceras, creatures that were once trapped beside a waterhole by a torrent of volcanic ash falling from the sky. Nebraska, of course, plays host to not a single volcano. Neither did Wyoming when these beasts died 10-million years ago. The volcanic ash that the animals breathed in and that suffocated them has been traced to the Snake River Valley in south-central Idaho 1,000 miles away. All those millions of years ago, the teloceras herd that was unearthed in Nebraska just half a century ago was overwhelmed of a colossal spasm of the Yellowstone hotspot.
Try to imagine, if you will, what a volcanic eruption would be like that would be capable of raining heavy loads of ash on nearly one-third of the continental United States and a sizable fraction of western Canada. That is what Yellowstone is capable of doing. It is also capable of dropping global mean temperature by ten degrees or more and depressing those temps for a decade. That’s a chilling thought, isn’t it?
No wonder geologists scramble when Yellowstone begins to throw continuous seismic fits. The last time Yellowstone created hell on earth via a super-eruption was 640,000 years ago. It can be argued, I suppose, that a Yellowstone eruption is overdue.
Our species has never experienced a cataclysmic eruption of the Yellowstone caldera. However, our kind was nearly driven to extinction by the disintegration of a massive volcano in Indonesia 74,000 years ago by the name of Mt. Toba. All that is left of Toba is a 60-mile-long crater lake by the same name. Geologists and geneticists, citing evidence in the rock and in our very DNA, postulate that the population of our species on the planet at the time may have been winnowed down to as few as 5,000 survivors.
When Mt. Toba turned to dust and brought volcanic winter to the planet for years, we humans understood our environment intimately and knew how to scratch a living directly from the forests, oceans, grasslands, and deserts. Today, almost no one possesses the skills or knowledge that made it possible for our ancestors to squeeze through the worst disaster imaginable and rebound in numbers that will soon, within a generation, close in on 10 billion.
Our current technological prowess and remarkable global adaptability has allowed us to become the most successful single large species to ever evolve since multi-cellular animal life burst onto the world stage during the Cambrian Explosion more than half a billion years ago. Yet we are divorced now from a direct connection to the land that sustains us. We have, to a substantial degree, set a trap for ourselves. Over grand spans of time, super-large natural disasters do occur. They are inevitable.
Yellowstone caldera is going to tear itself apart at some awful moment in the future, perhaps in a few years, perhaps in 100,000. Or maybe the culprit will be Taupo caldera in New Zealand, Pacana in Chile, Aira in Japan, or Long Valley in California. When the cold descends for years following a future super-eruption, global agriculture production will decline drastically or fail outright and leave untold billions without the calories needed to sustain themselves.
Breathe easy over Yellowstone, though. The chances of a super-eruption anywhere on earth are miniscule during anyone’s lifetime, but it isn’t zero. The Mt. Tambora eruption of 1815 – a magnitude-less explosion than the Toba event 74,000 year ago – brought on the Year Without Summer in 1816 in the northern latitudes. That was just a wee bit more than 200 years ago. Fifty years before Tambora vanished in hellfire, the ‘Misty Hardships’ spawned by the nine-month Laki volcanic eruption in Iceland brought famine and untold misery to most of Europe and North Africa.
The next time the radio is droning away or you are watching television and names such as Merapi or Nyiragongo, Pululagua, Guntur, or even Rainier are aired, cup an ear with your hand and listen intently. Those fire mountains are the stuff from which nightmares can be forged.
Sleep tight.
Can’t sleep now? Pick up a copy of The Yellowstone Traps at Amazon.com and spend your next volcanic winter hidden well beneath the covers with a flashlight.
