PORTLAND, Ore. (KOIN) — The heavy rains washing over the Pacific Northwest this week could cause landslides along steep hillsides and “debris flows” in areas burned by recent wildfires, the Oregon Department of Geology and Mineral Industries warns.
Areas most at risk of slides include Northwest Oregon’s Coast Range and Oregon’s North Coast. The National Weather Service has issued a flood watch for these areas that will remain in effect until late Tuesday night.
“Debris flows are rapidly moving, extremely destructive landslides,” the Oregon Department of Geology and Mineral Industries said. “They can contain boulders and logs transported in a fast-moving soil and water slurry down steep hillsides and through narrow canyons.”
Debris flows, the state agency said, can easily travel for more than a mile and move faster than a person can run. People living, working or traveling in at-risk areas are advised to track the ongoing weather conditions. State geologists are asking for people in affected areas to be on alert and listen for unusual sounds like snapping trees or knocking boulders, which could signal an oncoming slide.
“People, structures, and roads located below steep slopes in canyons and near the mouths of canyons may be at serious risk,” DOGAMI said.
If evacuations are ordered in connection to possible landslides, or there are signs that a landslide may occur, people are urged to leave immediately. Be advised: A trickle of mud or debris may be the beginning of a larger slide. Waterways may also be a way to foresee impending landslides.
“If water in a stream or creek suddenly turns muddy or the amount of water flowing suddenly decreases or increases, this is a warning that the flow has been affected upstream,” DOGAMI said. “You should immediately leave the area because a debris flow may soon be coming downstream.”
Travelers are asked to use extreme caution and assume that all roadways in the aforementioned areas are unsafe. Roadside embankments may also fail due to the extreme weather, dumping rock and debris into the road.