2 years later, Glacier Peak seismometers delayed again

GLACIER PEAK — Federal efforts to install additional seismometers around Glacier Peak have been delayed by ground conditions and logistical issues.

In remote wilderness, 20 miles as the crow flies east of Darrington, the U.S. Geological Survey classifies Glacier Peak as a “very high threat” volcano because of its close proximity to communities like Darrington, Concrete and Arlington, previous eruptions and air traffic.

A 2018 assessment from the Geological Survey gave “very high threat” rankings to Mount Rainier, Mount Baker and Mount St. Helens. Mount Adams is considered a “high” threat.

Glacier Peak is the 15th potentially deadliest volcano in the nation, out of 161, according to the assessment.

The Geological Survey plans to install seismometer and GPS units to measure for earthquakes and ground deformation. The technology would work in tandem, with the monitors sensing shaking or shifting, and the GPS noting the most minuscule movement in the actual ground where the monitors are placed.

The U.S. Forest Service green-lighted the addition of four monitors and an upgrade of the current monitor in July 2022, with plans to install the technology in the summer of 2023. But the installation has yet to happen.

Jon Major, the scientist in charge of the Cascades Volcano Observatory, explained a last-minute challenge bringing equipment to the field crews via helicopter postponed the work. But crews spent two days hiking to the planned sites to gather additional information. The delay turned out to be beneficial because the crew found unstable ground at some of the planned sites, Major wrote in an email.

“This new information has caused us to rethink what we need to do to actually install the instruments,” he added.

He said the crew found there was no solid ground at some sites to attach the GPS units.

“If they are not in stable rock, they can shift around (owing to snow loading, freeze/thaw movement of the soil, etc.) and that causes errors in the measurements — especially when we are trying to measure changes in the ground surface on the order of centimeters to perhaps a couple tens of centimeters,” he said.

The group is targeting to revisit Glacier Peak in the summer of 2026, giving engineers enough time to come up with solutions to make sure the monitors can function reliably in tough conditions, Major said.

Just because a Glacier Peak eruption would be dangerous doesn’t mean it’s likely to happen anytime soon, Major said.

Around 13,000 years ago, the volcano erupted in one of the biggest explosions the Cascades have experienced since the last Ice Age, and the mountain ejected five times as much rock as the Mount St. Helens eruption in 1980.

Eliza Aronson: 425-339-3434; eliza.aronson@heraldnet.com; X: @ElizaAronson. Eliza’s stories are supported by the Herald’s Environmental and Climate Reporting Fund.