It was 42 years ago this week, at 8:32 AM on May 18, when the ground beneath Mount St. Helens, 120 miles from Seattle, began to shake violently. A magnitude 5.1 earthquake caused the largest debris avalanche observed in our planet’s recorded history, depositing enough material in the North Fork Toutle River Valley to fill 1 million Olympic-sized swimming pools. The landslide depressurized the volcano, bringing the stone to life with a fierce, sudden force. Mount St. Helens erupted.
The summit and north face of the mountain fell away in three large chunks. The first block plunged into Spirit Lake and created what’s called a seiche, a wave that oscillates from one side of an enclosed body of water to the other, the way water sloshes in a bathtub. But in this case the water in Spirit Lake may have traveled 850 feet up the surrounding hills as it crashed back and forth, pulling trees, animals and rocks down with it.
The second block was sent northward crashing over a thousand-foot-high ridge and coming to rest four miles from the mountain. The third block, a giant chunk of rock from much closer to the mountain’s core, rumbled 14 miles down the valley. Twelve days later, pieces of this third block were still hot to the touch.
With part of its face sheared off to reveal a new volcanic crater, the Plinian eruption began. Marked by a similarity to the eruption of Mount Vesuvius, immortalized by the ancient Roman writer Pliny the Younger, Mount St. Helens sent a cloud of ash and rock fragments 15 miles or 80,000 feet into the air, a height of more than twice the typical cruising altitude of a commercial jet. This material ultimately fell back to earth, spread over an area of several thousand square miles
This phase of the eruption continued for nine hours, sending wave after wave of pyroclastic flows of broken rocks, ash, and silica-rich material into the valley. These waves of cooled, solidified magma created the Pumice Plain in front of the mountain, a six-square-mile area of gray material. This material included both the pyroclastic flows and tephra, the ash and rocks that fell from the sky following the eruption. By the time it settled at the foot of the mountain, this gray covering extended to the southern shore of Spirit Lake. Tens of thousands of logs, mowed down by the eruption, came to rest on the surface of that lake, matted together like makeshift rafts.
This was a hugely dramatic event. The fires, mudslides, and floods set off by the volcano’s eruption killed 57 people, along with countless plants and animals. It was also, from a scientific perspective, something novel and well worth studying. It was death and destruction on an unthinkable scale, and at the same time an opportunity to see how the natural world might recover from such a disruptive event.
Within days, brave and persistent scientists found their way into the blowdown zone and the pumice plain, using helicopters to visit the devastated landscape. They expected to find a lifeless place. One scientist described his first visit by saying “Everything was gray. Nothing had been left standing… It was like flying over the moon.” But then, within days, scientists began noticing fireweeds poking up through the ash. As that same scientist put it, “Right off, all of us smart ecologists realized we didn’t have the correct working hypothesis.” Life, the ecologists and geologists quickly realized, was going to come back to Mount St. Helens much, much faster than they had anticipated.
It’s that story, the story of inspiration and recovery, that Eric Wagner tells in his marvelous book, After The Blast: The Ecological Recovery of Mount St. Helens, published two years ago and out this month in a paperback edition from the University of Washington Press. Wagner holds a PhD in biology from the University of Washington and is the author of Penguins in the Desert and coauthor of Once and Future River: Reclaiming the Duwamish. He climbs Mount St. Helens annually.
Wagner’s book highlights the amazing work done by a cast of characters who were among the first scientists to arrive at the blast site. More urgently, it chronicles nature’s resiliency and the power of our ecosystems to restore and reinvent themselves.
Within 24 hours of the eruption, rescue workers and scientists reported seeing insects flying around the blast zone with a surprisingly large number of spiders parachuting in and incinerating on contact with the Pumice Plain. This phenomenon, called arthropod rain, laid a foundation of organic matter on top of the ash, attracting beetles and other insects who were able to subsist in the desiccated area without any plants to feed on. That dead insects could allow resident animal populations to assemble in an area devoid of plants was just the first surprising discovery at the base of Mount St. Helens.
Within weeks, ecologists began to see more signs and varieties of life, from plants like prairie lupines to small, scurrying mammals like pocket gophers. The lupines dug their woody stems into the Pumice Plain and, like tiny factories, began fixing nitrogen from the air into the soil. Meanwhile, the pocket gophers dug tunnels, turning over huge amounts of soil and churning through ash, a boon to other plants and flowers and seeds blown into the area.
Within months, geologists had reconstructed the discrete stages of the eruption from the evidence on the ground. They saw the mountain change almost under their feet as life returned to the site.
Studying everything they could mark off, these scientists set to work. For these men and women, the event inspired a burst of studies that shaped their careers and, in some cases, revolutionized their fields. They set up vantage points where they could observe how the landscape changed, and recorded their findings. The science that the landscape called for was not the active, experimental kind. It was something altogether more difficult. It was slow work that required patience and persistence, work that required giving the landscape the chance “to speak for itself,” as Wagner puts it.
Systematically observing the mountain’s recovery, scientists learned valuable lessons about how ecological succession works. By simply noting changes in the landscape over the months and years following the eruption, they learned how plant and animal species move into an area after a natural disaster. Altogether these studies provided a map and a record of the way life returns and new ecosystems form following disruptive, destructive events. A mixture of hardy survivors and new invasive species that take advantage of a disruptive event like a volcanic eruption, these ecosystems can grow and change in myriad surprising ways. Nature abhors a vacuum, and Mount St. Helens now serves as living, breathing proof of that scientific dictum.
The area was never totally devoid of human influence. A desire to prevent further loss of human life and property in areas surrounding the blast and blowdown zones meant that the Army Corps of Engineers was brought in to take measures that prevented new rivers and lakes from flooding nearby towns. Still, the mountain became the only natural experiment of its kind when, two years after the eruption, Congress passed and Reagan signed a bill conserving 110,000 acres surrounding the mountain for scientific study.
Ultimately, over the last 42 years, Mount St. Helens showed the world just how powerful nature is, and just how quickly it can recover when left to its own devices. The scientific work undertaken at the site, described with verve and passion in Eric Wagner’s book, is almost certainly one of the reasons that the environmental movement has increasingly promoted the concept of re-wilding. Conservation in itself, and returning lands heavily impacted by human activity to a wilder state, are increasingly seen as an important tool in the fight to counter climate change.
It’s not difficult to draw a line from the work done on Mount St. Helens to President Biden’s pledge to conserve 30 percent of America’s lands by 2030. Whether he will be able to accomplish that goal remains to be seen, though he is making progress. One can only hope that we might give more of America’s landscape the ability to speak for itself – just as we did at Mount St Helens more than four decades ago.
