When the Cascades Volcano Observatory was asked to help with the response to last month’s fatal landslide in Snohomish County, the Vancouver-based operation turned to familiar tools.
A small team of CVO scientists brought sophisticated ground-monitoring equipment capable of detecting the slightest movement. Among the most versatile are helicopter-deployed “spider” units, each equipped with motion-sensing GPS technology and sensitive geophones.
The CVO deployed four spiders to take measurements on and around the slide area, said hydrologist Rick LaHusen, who spent four days near Oso this week. The same technology was used to monitor Mount St. Helens during its last eruptive phase from 2004 to 2008, he said.
“The spiders are a great tool for rapid, temporary response,” LaHusen said. The CVO, which operates within the U.S. Geological Survey, has more than a dozen spiders available for use in the region.
Scientists are also using visual observations, terrestrial laser scanning, extensometers and conventional surveying equipment to monitor the slide area, LaHusen said.
After the initial slide that devastated the small community northeast of Seattle, the equipment so far hasn’t measured significant movement that would put searchers on the ground in danger, he said.
Workers and volunteers continue to comb through a sea of mud and debris left by a disaster that left dozens of people dead or missing.
The event has prompted state and federal emergency declarations amid a Herculean response effort.
LaHusen saw the aftermath for the first time this week.
“Words really can’t describe it,” LaHusen said. “It’s a pretty grim scene.”