Visitors again to be sitting on a volcano

SUMMIT OF MOUNT ST. HELENS — The view from the top of the crater offers a startling look at the forces that make, shape and blow apart the volcanoes of the Pacific Northwest.

Blue-white steam rises out of numerous vents.

A huge rock spine appears stationary but is slowly rising up from the center of the crater, propelled by magma rising to the surface in amounts equal to a pickup-truck load per second.

And there is a glacier, once shaped like a horseshoe, now chopped into two crevassed pieces by the forces of heat and uplift.

Mount St. Helens is indeed an active volcano, and for nearly two years the ash, projectiles and other hazards were deemed too risky to allow climbers to trek up to the summit. But the U.S. Forest Service is reopening the summit route July 21 and on Thursday offered journalists an early opportunity to make the climb and take a gander at the changes wrought by a new eruptive phase that began in September 2004.

"Our bent is to let people get as close as possible," said Claire Lavendel, forest supervisor for the Gifford Pinchot National Forest, who made the decision to reopen the mountain in consultation with the U.S. Geological Survey. "We don't want people to be afraid. We want them to be respectful of what is going on."

Geologists say that the volcano, which rises to more than 8,360 feet, appears to have settled down into a predictable pattern as magma continually moves to the surface. It is not venting large quantities of gas or unleashing larger earthquakes that could hint of an explosive eruption.

So the risks appear reasonable, say the U.S. Geological Survey scientists. And the mountain, which used to attract more than 11,000 climbers a year, will be open again after nearly two years.

The climb and descent typically take six to 12 hours. Though not technically difficult, some people run into trouble with strained muscles, sprained ankles, dehydration, uncontrolled descents and by veering off route.

In this active phase, there are other risks. Forest Service officials recommend that hikers bring dust masks and goggles to protect against ash clouds. They suggest a hard hat to protect against gravel-sized rock that could occasionally fall at the crater rim.

For those who have climbed this volcano over the past two decades, the route to the summit covers familiar ground. You hike through fir forests, move up a steep basalt ridgeline and finally trudge through fine-powdered gray ash that yields like snow to the soles of your hiking boots.

The central feature of the summit is still the vast crater, which stretches some two miles from rim to rim. It was formed by the epic blast of 1980, when a powerful explosion and history's largest recorded landslide reshaped the volcano.

By the mid-1980s, a lava dome had formed inside the crater, which became familiar to climbers who — beginning in 1986 — were allowed to make the ascent.

Now that old dome is barely visible, dwarfed by the lava rock that has surfaced since the new eruption began in 2004.

At first, this new lava dome grew in whaleback-like formations that built up and shattered into huge piles. On Thursday, some of those piles were being examined by a team of scientists who — from the crater ridge — looked like tiny dots of orange.

But most of the magma now appears to be building the new vertical spine, which rises to a height of about 720 feet, although it frequently splinters and crumbles. On Thursday, the spine — pockmarked with fumaroles around its midriff — was the site of frequent rockfalls that made a curious, almost metallic clinking sound.

It is unclear what is pushing this magma to the surface, since it lacks most of the gas normally associated with an eruption. One theory speculates there might be another, deeper pool of magma that is richer in gas and pushing this more shallow pool into the crater. If that theory is correct, this eruptive phase could eventually get more violent.

If there are any major changes in the volcano's activity, the Forest Service could opt to once again shut down the climbing route.

But for now, Lavendel says she is eager for people to share the volcano, the science and the views.

"This is what it's all about — it sparks something inside me," Lavendel said. She wants to see lots of young people climbing the mountain, some of whom may become the next generation of vulcanologists.

"We want that to happen."

Hal Bernton: 206-464-2581 or hbernton@seattletimes