Don't worry, Mount St. Helens isn't exploding right at the moment (*sadface*). But if you'll step into the Vulcan Mark III TimeMachine with me, we'll go watch her wake up!
Thirty-five years ago today, the earth beneath our beloved Mount St. Helens began quivering. The volcano stirred, restless. Soon, she would wake...
Earthquakes tell geologists a lot about what's going on with a volcano. Earthquake swarms can signal magma on the move. Volcanologists have come to recognize particular patterns, such as harmonic tremors, that often signal the onset of an eruption.
Seismologists had been monitoring earthquake activity at Mount St. Helens for eight years. From 1975 until early 1980, only a few dozen earthquakes had been recorded near the volcano. But on March 15th, a swarm began that signaled the potential for an eruption. Less than two weeks later, the volcano erupted for the first time since 1857. Within two months, she blew herself apart.
From the USGS paper that warned that "the current quiet interval will not last," to her awakening, increasing activity, and through her historic May 18th, 1980 eruption, you can read all about Mount St. Helens right here!
Prelude to a Catastrophe:
Dedication: The Geologists Who Died at Mount St. Helens. Yes, geologists plural. We’re fortunate most of the scientists working on the mountain survived, but we did lose a few of our own. They showed incredible dedication. This series is dedicated to them.
Prelude to a Catastrophe: “The Current Quiet Interval Will Not Last…” In 1978, USGS geologists Dwight Crandell and Donal Mullineaux published a paper that spelled out the possibilities of a future eruption of Mt. St. Helens in stark detail. The work they did on this volcano prevented the catastrophe from being far worse than it was. This paper put everyone on notice: we have a dangerous mountain in our midst, and she could wake up at any time.
Prelude to a Catastrophe: “One of the Most Active and Most Explosive Volcanoes in the Cascade Range.”Dwight Crandell had nearly completed an exhaustive study of Mount St. Helens’s eruptive history when she added to his workload in 1980. She had quite the history of hijinks. Crandell’s study of her violent past helped predict her current behavior.
Prelude to a Catastrophe: “The Unusual Character of the Seismic Activity Became Clear.” In mid-March of 1980, a swarm of earthquakes unprecedented in our experience of Cascades volcanoes put everyone on notice: something big was happening, and it was only getting bigger…
Prelude to a Catastrophe: “Something Dramatic.” One of the seismologists watching the earthquake swarm unfold later wrote, “We did not see how this activity could continue without something dramatic happening.” And something dramatic did.
Prelude to a Catastrophe: “Pale-blue Flames.” Eerie blue light dances within the crater, and geologists scramble to protect the public as Mount St. Helens roars awake.
Prelude to a Catastrophe: “The Only Way It Can Stabilize is to Come Down.” The bulge grows at astonishing rates. David Johnston and his fellow geologists know that the side of a mountain can swell only so far before gravity pulls it down. There is no question of if, only when it will fall.
Prelude to a Catastrophe: “Our Best Judgement of Risk.” While the bulge pushes out at upwards of five feet per day, geologists assess other signs that Mount St. Helens, despite the lack of explosions, poses an enormous risk to life and property. They risk their own lives to protect ours.
Prelude to a Catastrophe: “The Volcano Could Be Nearing a Major Event.” Phreatic eruptions resume, steam pours from fumaroles and cracks, the bulge continues to grow… and the countdown nears 0.
The Cataclysm: “Vancouver! Vancouver! This Is It!” The ominous bulge on Mount St. Helens’s north flank gives way, beginning a cataclysmic lateral eruption. We see the events of that day through the eyes of those who survived – and through the last transmissions of some who didn’t.
The Cataclysm: “One of the Most Dramatic Mass-Movement Events of Historic Time.” In which we explore the largest landslide (in volume) in recorded history. When the bulge came down, it thundered down the mountain, filled valleys, overran ridges, plunged into Spirit Lake - and unroofed the cryptodome, which was only holding together under pressure.
Interlude: “Lateral Blasts of Great Force.” In which we explore the history of directed blasts, and meet a few of the precursors to the Mount St. Helens eruption.
The Cataclysm: “A Sudden Exposure of Volatile Material.” When the landslide exposed the cryptodome, pressure was released on a very hot, very forceful collection of young dacite magma. The resulting blast was one of the most incredible explosions ever witnessed by volcanologists - and placed everyone near it in mortal peril.
The Cataclysm: “That Whole Mountain Range Had Just Exploded.”In the first few minutes of the directed blast, life within a few kilometers of the volcano's north face was extinguished, and people nearby found a sinister black cloud of roiling rock bearing down on them. It looked to them as if the entire range had erupted, and many of them believed that would be their last sight.
The Cataclysm: “A Boiling Mass of Rock.” Survivors within the blast zone saw the blast cloud approaching. The lucky ones had vehicles and an open road: they fled, with no guarantee they could outrace the eruption.
The Cataclysm: “I Was Just Instantly Buried.” For the people caught within the blast cloud with no means of escape, survival could hinge on fragments of luck: whether a tree fell on you or left a hollow that protected you; whether you'd chosen to camp behind a ridge; where you fell when the blast hit. Not everyone was so lucky.
Interlude: When Vehicles Become Part of the Geologic Record. Many vehicles - trucks, cars, logging equipment - were caught in the lateral blast. What does the damage on them tell geologists about the conditions of the cloud?
Interlude: What Vehicles Say About Temperatures Within a Volcanic Blast. In the second part of our vehicles-that-had-a-very-eventful-day miniseries, we take a look at what the high temperatures within the blast cloud did to the vehicles, and how geologists determined what those temperatures were by
having a blast torturing auto partsperforming carefully controlled experiments.
The Cataclysm: “A Horrible Crashing, Crunching, Grinding Sound.” Mount St. Helens had many magnificent stands of trees. Emphasis on had. We begin to explore the havoc wreaked on forests young and old when a directed blast heads their way.
The Cataclysm: “All of the Trees Seemed to Come Down at Once.” We follow the blast path as it erodes trees right off the hillsides. That's right.Erodes. Weird, right?
The Cataclysm: “From Unbaked Fragments to Vitreous Charcoal.” Wherein we learn how to properly bake, flambé, and sear a damp Pacific Northwest forest.
The Cataclysm: “The Path of Maximum Abrasion.” The eruption sandblasted trees for dozens of kilometers. It's amazing what we can learn from an eruption through patterns of abrasion.
The Cataclysm: “Fully Down and Buried.” From the volcanic debris deposited on downed trees, geologists are able to visualize the sequence of events as the blast cloud ripped through the forest.
The Cataclysm: “Stripped from the Proximal Forest.” Trees and fragments of trees become part of the volcanic deposits.
To be continued...
There's so much interesting stuff surrounding Mount St. Helens that a series can't accommodate it all. And so we have Addenda:
To Mount St. Helens on the 32nd Anniversary of Her May 18th, 1980 Eruption. In which I write a letter to the volcano that changed my perception of the world forever.
Dave Crockett’s Narrow Escape. KOMO News reporter Dave Crockett woke up early on the morning of May 18th with the urgent sense that he should go to the mountain, and ended up trapped in the catastrophic eruption. His film of the experience is one of the eeriest I've ever seen.
Interlude: “To Paradise With Pleasure Haunted With Fear.” In which I describe my childhood volcanoes, and how I overcame a volcano phobia by staring into the steaming ampitheater of Mount St. Helens.
A Survivor’s Tale: “Half the mountain exploding over our heads.” A reader writes in to tell us of the day when Mount St. Helens erupted, and an appreciable part of the mountain traveled directly over him.
Happy eruption anniversary! Enjoy your travels back to the days of splodey volcanoes in the continental United States (and the era of feathered hair).