The landslide was discovered when state workers in the area noticed cracks on a hillside road south of Highway 530.
A stretch of Highway 530 will remain closed through the Monday morning commute as geologists continue to evaluate a landslide south of the highway near Oso in rural Snohomish County.
Geologists from the state Department of Natural Resources (DNR) were investigating the landslide Friday and Saturday, trying to get a sense of how fast it could be moving.
Signs of a slide were first discovered Tuesday by state Department of Transportation workers, who noticed cracks on a hillside road. DNR workers investigated Friday and saw signs of movement.
Cracks in the roadway were about 6 inches wide Tuesday, but had spread to 2 feet wide by Saturday. The hillside has dropped about 4 feet vertically, officials said.
It is unclear if that shift occurred slowly or suddenly, state geologist Dave Norman said at a news conference Saturday.
DNR has placed monitors and sensors near the landslide and will continue to evaluate the readers over the weekend.
The slide is about 1.5 miles west of the massive 2014 landslide that killed 43 people in the Steelhead Haven neighborhood in Oso — and it’s on the opposite side of the highway.
The highway is closed from Oso Loop Road to C-Post Road as a precaution, a state Transportation Department spokeswoman said Saturday. The department will reassess the situation Monday, and if no more movement occurs between now and then, there’s a good chance the highway will reopen.
There is no debris from the landslide on the highway.
Officials recommended Friday night that people living nearby evacuate. Residents of eight homes did, while those in two homes decided to stay put, according to the Transportation Department. One house is on the same side of the highway as the slide, and the others are north of the roadway.
Geologists went to the area late Friday but ran out of daylight. They restarted their investigation early Saturday.
“It appears it didn’t move overnight, so that’s a good thing,” DNR spokesman Joe Smillie said.
Survivors of the 2014 slide settled a civil case last fall for $60 million. The plaintiffs alleged that the state and a timber company had taken actions that increased the risks of a slide.
Norman, the geologist, said a “limited amount of logging” had occurred in the 25-acre area of the slide.
After a “particularly wet winter” this year, the state is busy investigating slides across Washington, Smillie said. Geologists have investigated 100 slides in just the last month in the northeast corner of the state.
The slide near Oso is on privately owned land. DNR has access to the hillside road where cracks appeared.
It’s another reminder of the tragic slide of three years ago, Oso Assistant Fire Chief Toby Hyde said at a news conference Saturday.
“We just seem to keep ripping the scab off, and it keeps bringing up some tough stuff,” he said, but added: “This is a really resilient community.”