VANCOUVER, Wash. - Scientists with the U.S. Geological Survey’s Cascades Volcano Observatory have configured four “spiders” to watch over workers trying to recover victims from the Oso landslide.
“The sole purpose of putting this out on the landslide is to make sure that the workers who are there involved in the recovery operation are safe and not at risk from additional motions on that landslide,” said Rick LaHusen, who is responsible for the spider and remote sensing program.
What is a spider? It’s a stainless steel box that holds a computer, monitors like geophones that pick up sounds from the earth, earthquake seismometers and batteries. It all sits up a tripod of legs and can run unaided for a year.
They were developed primarily for monitoring volcanoes. You can drop them by helicopter into high hazard areas that would kill a scientist on the ground.
Inside a volcanoes crater, the spider can sniff for the chemical makeup of gasses – gasses that tell a lot about what’s going on during an eruption, but poisonous to people. At times, it seemed like they couldn’t make them fast enough as flying rocks and debris thrown up by the eruption flattened many of them back then.
Three are used on the Oso slide. One is on top of the scarp, the 200 foot tall sheer cliff that is where the slide broke free from. Another is on the larger pile of debris, and a third is along the side of the scarp. Instead of sniffing for gasses, these spiders are equipped to listen for cracks, vibrations or any movement that could signal that more debris could come down.
“We’re seeing small adjustments going on within the block,” said LaHusen, referring to normal settling of the slide debris. “And we’re seeing the little soil slips coming off the landslide scarp.”
So far, nothing dangerous.
LaHusen says the USGS is in talks with the Washington State Department of Transportation about continued monitoring for the eventual re-opening of State Route 530.