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Mount St. Helens after 30 years: Life and lessons on a volcano

The yawning crater of Mount St. Helens is obscured by clouds on an early May day as monument scientist Peter Frenzen leads a group along the Hummocks Trail through the jumbled landscape of the North Fork Toutle River’s upper watershed.

When visible, the crater is a vivid reminder of May 18, 1980 — the day the top of the volcano slid and blew apart.

Some 3.7 billion cubic yards of mountain was dislodged that morning by an earthquake beneath the summit, triggering the largest landslide in recorded history. Within minutes, a 14-mile-long stretch of the river valley and surrounding old-growth forest was buried to depths of 150 feet with sand-to-boulder-size material that once shaped the volcano’s symmetrical cone.

“We’re standing on top of the missing piece of the mountain,” Frenzen explained, recalling the eerie gray landscape where nothing survived the debris avalanche and ensuing explosive eruption of the volcano.

Thirty years later, the pieces are in place for ecological recovery. The plants, animals and trees that have re-established in the most barren place in the 230-square-mile blast zone are a testament to the resiliency of Mother Nature.

“What you see is 30 years of trial-and-error seeding by plants and animals,” said Frenzen, who has worked on the flanks of Mount St. Helens since shortly after the eruption. “It’s come a long ways. … When we first started doing research here, there was nothing. We’d get excited to see a spider’s web.”

Early on, there was a certain randomness to the recovery. For instance, the mountaintop deposits gave birth to 150 ponds and lakes, compared with 35 before the blast, noted U.S. Forest Service research ecologist Charlie Crisafulli on an earlier hike through the landslide zone.

“The shorelines along the ponds were where the first seeds took root,” Frenzen recalled. “The ponds were kind of like oases five to 10 years after the eruption.”

Today the ponds and wetlands are thick with hardwood stands, providing wood for a huge beaver dam framed by cattails and chirping red-wing blackbirds. The ponds are seasonal homes for one of the largest known populations of western toads, Frenzen said.

In the open areas of the landslide zone, clumps of grass grow where elk deposited droppings rich with grass seed. A tree trunk speared into the ground shades a huckleberry plant, its seed deposited by a woodpecker or other cavity-nesting bird that used the snag.

“A lot of plant life is riding into the landslide zone in the gut trail of animals,” Frenzen said.

While soil has yet to form atop the rocky rubble of the former mountain top, lime-green moss grows everywhere in the open areas. Decaying leaves, insects and other organic litter have formed a coating of humus rich enough in nutrients to support mosses and wildflowers such as prairie lupine, paintbrush and false dandelions.

“The filling-in process — I liken it to the pixels on a television screen,” Frenzen said. “There’s so much more green and so many flowers in bloom in the summer.”

Outnumbered by the red alder, willow and cottonwoods, the conifer trees, including Douglas, silver and noble firs, western hemlock and lodge pole pine, are scattered across the landscape. Many of them are heavily browsed by elk.

“The forest is here; it’s just being delayed by the elk,” Frenzen said.

He referred to a population of elk in the blast zone estimated to be 700 animals 10 years after the eruption, peaking at more than 2,000 five years ago and roughly halved this year by starvation and increased hunting.

In another 20 years or so, the hardwood trees will give way to the conifer forests that dominated the upper Toutle River Valley before the eruption.

Left to their own devices, those forests will once again mature into the old-growth forests of the pre-eruption era.

But that all depends on what happens at Mount St. Helens in the decades ahead.

“When will the mountain erupt again?” Frenzen repeats the question he’s so often asked. “Only the mountain knows.”

SOME LESSONS LEARNED

Since the most-recent dome-building eruptions ended in early 2008, the mountain has been quiet, averaging about one very minor earthquake a day, said Seth Moran, a U.S. Geological Survey seismologist stationed at the Cascades Volcano Observatory in Vancouver, Wash.

Scientists know the general condition of Mount St. Helens thanks to an array of monitoring equipment that keeps tabs on earthquakes, deformities, volcanic gases and other precursors to an eruption.

“The monitoring network is one of the best in the world,” Moran said.

By comparison, in 1980 scientists weren’t sure whether the March 20 earthquake that marked the reawakening of Mount St. Helens was beneath the volcano or just nearby, Moran said.

Monitoring equipment developed for use at Mount St. Helens has been installed around the world at other active volcanoes such as Mount Pinatubo in the Philippines and Redoubt Volcano in Alaska.

“Lives have been saved in the past 30 years since Mount St. Helens erupted,” Moran said. “Being able to measure the signs and symptoms when a volcano becomes active is like having a playbook — it reduces some of the uncertainty.”

Debris avalanches were a poorly understood volcanic event prior to Mount St. Helens, Moran noted. Since the eruption 30 years ago, scientists around the world have discovered more than 200 prehistoric debris avalanche deposits from steep-sloped volcanoes such as Mount St. Helens, according to USGS scientists.

Volcanoes don’t just explode — they fall apart.

DISRUPTING AVIATION

The 1980 eruption of Mount St. Helens triggered the first documented case of jet power loss from volcanic ash, something now considered one of the biggest public safety threats posed by a volcanic eruption.

“The lesson has evolved and grown over the past 30 years,” said John Ewert, a USGS volcanologist who works with meteorologists and aviation authorities internationally to monitor and respond to ash clouds so aircraft can avoid potentially fatal encounters. “Mount St. Helens was a watershed event in understanding the risk of volcanic ash to aviation.”

The most recent example of ash and aviation conflicts also is the most dramatic. The April eruption of Iceland’s Eyjafjallajokul led to the shutdown of air space for several days over much of Europe.

About 200,000 passengers fly over Cascade volcanoes every day, underscoring the need for real-time monitoring of volcanoes, Ewert said.

The eruption of Mount St. Helens linked many scientific disciplines together — scientists studying three decades of volcanic activity and ecological rebirth. But just as important, it raised public awareness about the power and destruction that volcanoes here in the Northwest can unleash, noted Pat Pringle, a Centralia College earth sciences professor and geologist by training.

“The other volcanoes are alive now, thanks to Mount St. Helens,” Pringle said.

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