Rebirth of a shattered landscape


Nature: Life returns to the slopes of Mount St. Helens, site of a cataclysmic eruption almost 20 years ago.

October 21, 1999|By M. Dion Thompson | M. Dion Thompson,SUN STAFF

MOUNT ST. HELENS, Wash. -- The season's first snows are falling. The land is going to sleep. And another year's renewal is at an end.

Nature is working wonders here, reclaiming a landscape scarred by volcanic eruptions, turning the mountain and its surrounding valleys into an outdoor laboratory.

None of this could have been expected the morning of May 18, 1980. That was when David A. Johnston, a U.S. Geological Survey scientist, radioed to his home base: "Vancouver! Vancouver! This is it!"

A 5.1-magnitude earthquake shook the mountain. Seconds later, the entire north slope collapsed, unleashing the largest landslide in recorded history. Then came the eruption, a 10-megaton explosion -- 500 times the power of the atomic bomb dropped on Hiroshima.

The destruction was immediate and devastating: millions of trees knocked down and thousands left standing but dead, the blast having sucked the life out of them; raging rivers swollen with mud, ash and debris. In three minutes, 156 square miles of old-growth forest was destroyed. It will take an estimated 200 years to restore it. Fifty-seven people, including Johnston, died.

Events are being planned to commemorate the 20th anniversary. People will remember those who lost their lives and those who worked to save lives and repair the mountain. And they will consider what nature has done.

"It quickly became very obvious that what [the eruption] leaves behind is a lot of living and dead biological material. It's not a clean slate," says Peter Frenzen, monument scientist for Mount St. Helens National Volcanic Monument. "What is left behind is almost like a lifeboat for life returning to the area."

Frenzen and other scientists find something new each time they explore the monument's 150 square miles. Early on, just seeing a spider web in the blast zone brought joy. It meant life was fighting back. Then plants started to appear, followed by birds and elk. A decade later, trout were swimming in a lake ruined by the blast.

This rebirth has occurred many times at Mount St. Helens. The mountain is a mere 40,000 years old, a baby in geologic time. It is part of the Cascade Range, a rugged, 1,000-mile-long chain of volcanic veterans born from the grinding collision of the North American and Juan de Fuca tectonic plates.

Long before white men gave the mountain a name, Native Americans of the Pacific Northwest knew it as Law-We-Lat-Klah, "Smoker," or Loo-wit. Numerous eruptions tore it apart and gouged its sides, leaving it a snow-capped gem of startling beauty. Before the 1980 eruption, its summit stood 9,677 feet above sea level. It is now barely 8,300 feet.

The tree line, once thousands of feet up the mountain, has vanished, replaced by a gray, barren plain of pumice hundreds of feet deep. Slowly, though, life is returning to the shattered landscape.

"I guess the lesson is, life is very tenacious," says Frenzen.

In 1981, he and other scientists began plotting the recovery, mapping out areas. He says that in many of those areas "we didn't find one plant. Zero. Nada. So, what you see out there today is a huge amount of plant growth."

There are huckleberry and fireweed and waist-high fir trees. Northern pocket gophers, ground squirrels and deer mouse dart for cover. In one sense, life got lucky. Things would be much different had the volcano erupted later in the season. In mid-May, there was still a protective layer of snow.

"A lot of the animals weren't very active, the animals that live in burrows. They weren't actively hibernating, but in a sort of torpor, hanging out," says Frenzen. "Those that were underground and covered survived the blast."

Larger animals and birds did not escape the cataclysm. Some estimate that 1,500 Roosevelt elk and 5,000 black-tailed deer perished, along with thousands of other creatures. Now, more than 2,000 elk, among the largest herds in the state, are living around the mountain.

An entire forest is working to heal itself. Seeds blown in on the wind take root. Plants buried under snow and ash emerge, some appearing three years after the blast. Once the brush grew large enough, birds found nesting places and in turn left behind seeds picked up along the way. Some plants seem tailor-made for the mountain's pumice plain. The bacteria in the roots of alder and lupine help them pull nitrogen from the air.

At Spirit Lake, rainbow trout swim through cool waters. Before the eruption, Spirit Lake could have modeled for a postcard touting this breathtaking land of sky-blue waters. The lake's temperature averaged 42 degrees.

The explosion and landslide turned it into a boiling, roiling soup. The water temperature approached 100 degrees. Tons of vaporized or otherwise demolished trees, mud and rock slammed into the lake, sending a huge wave up the surrounding ridge. All that muck then slid back into the lake, raising Spirit Lake's floor 200 feet.

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