Cloaked in ice, Snohomish County’s volcano is a future danger

GLACIER PEAK — As the eruption of Hawaii’s Kilauea volcano has triggered evacuations on the Big Island and drawn international attention, Snohomish County’s own volcano slumbers in the wilderness east of Darrington.

Glacier Peak is considered a “very high threat” volcano by the U.S. Geological Survey, and the agency has labeled it a priority for improved monitoring. Threat levels are based on frequency of activity, types of eruptions, the hazards of those eruptions and how many people would be affected.

Glacier Peak doesn’t have the level of exposure Kilauea does, where fissures are opening in neighborhoods, said Seth Moran, scientist-in-charge of the USGS Cascades Volcano Observatory. But volcanic mudflows from a large eruption of Glacier Peak could reach communities in the Stillaguamish and Skagit valleys, and the volcano could spew ash as far as British Columbia.

It would be starkly different than what’s happening in Hawaii, Moran said.

An update from the Hawaiian Volcano Observatory on Monday described “lava fountaining, explosion of spatter more than 100 feet into the air, and an advancing lava flow.”

“The main thing that would be in common is that (Glacier Peak and Kilauea) are both volcanoes,” Moran said. “We wouldn’t see lava fountaining, we wouldn’t see fissures. The lava in Glacier Peak is much, much stickier than what’s in Kilauea.”

The two biggest hazards from Snohomish County’s volcano would be ash and lahars, or volcanic mudflows, which would be fed by glaciers melting on contact with hot volcanic rock. Mud, melt and debris roughly the consistency of wet cement would rush down the mountain.

“Lahars can go for a while and they can be very destructive,” Moran said.

Several communities, including Darrington, sit atop the remnants of such flows from millennia past.

Of Washington’s five active volcanoes, Glacier Peak is the most remote. The peak is named for more than a dozen glaciers that cling to its sides. It has produced some of the largest, most explosive eruptions in the continental U.S. and has erupted at least six times since the end of the last ice age, according to the USGS. Researchers estimate the most recent was less than 300 years ago.

More than a decade ago, an assessment by the National Volcano Early Warning System found that Glacier Peak needs better monitoring. A single seismometer, installed in September 2001, is the only station there.

The goal is to add four more monitoring stations. That project is in the permitting phase with the U.S. Forest Service, Moran said.

In 2014, researchers used Light Detection and Ranging, or LiDAR, to map Glacier Peak and hundreds of square miles around the volcano.

“It was a really successful survey,” Moran said. “Glacier Peak is a wilderness area with lots and lots of tall trees. It’s really hard to do field geology out there and see subtle land changes associated with volcanic activity. The LiDAR allows you to kind of strip away the trees and map the layers.”

The detailed elevation information on drainages coming off Glacier Peak allows researchers to better map the potential paths of lahars.

“Another episode could happen conceivably in our lifetimes,” Moran said. “One of our roles is to ensure that we’re ready when something happens at Glacier Peak, and to make sure that the community is ready.”

The monitoring station has tracked some small quakes, including a short-lived sequence around Thanksgiving of 2015, Moran said.

Mostly, though, Glacier Peak is quiet. More monitoring equipment would be needed to better pinpoint small quakes and determine their significance.

Moran urges people to know if they are within reach of Glacier Peak or other volcanoes, and to understand the type of eruption that could happen and what hazards might affect them. He also reminds them it could be a long time before Glacier Peak awakens.

“Part of being prepared is understanding what can happen, and the likelihood that it will happen,” Moran said. “Volcanoes have some mystique. They’re the tallest mountain we see on the horizon … Take them into account, keep them in mind, but don’t be running around thinking (an eruption) is something that could happen the next day.”

Kari Bray: 425-339-3439; kbray @heraldnet.com.