Climbers on Mount Baker photographed a recent debris flow across Boulder Glacier on the volcano’s eastern flank in early June — but the barrage of ice and rock was more a geologic curiosity than a real threat to most people.
Such debris flows occur occasionally and are not a concern to anyone except mountaineers, a Western Washington University geologist said. But observers will notice what resembles a river of gray on the 10,781-foot summit that’s about 30 miles east of Bellingham.
“It’s not a threat, it’s a scientific curiosity, and it will be very visible,” said Dave Tucker, research associate in WWU’s Geology Department and a board member of the Mount Baker Volcano Research Center. “There will be a dark streak on the glacier until there’s snow.”
They happen every three, four, five years and some of them are very large. If they happen when climbers are on the mountain, it can be a problem.
Dave Tucker, Western Washington University
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A debris flow is like an avalanche that scours the mountainside, gathering ice and rock and volcanic deposits in a mad downhill rush of material that’s the consistency of wet concrete. They can be deadly, such as the one in 1985 that struck Armero, Colombia, killing an estimated 20,000 people.
“They happen every three, four, five years and some of them are very large,” Tucker said. “If they happen when climbers are on the mountain, it can be a problem.”
Tucker said a debris flow in 2006 narrowly missed a group of climbers who were roped together for safety during an ascent.
“They can be sizable and they move fairly quickly, according to a witness in 2006,” Tucker said. “And they are fairly quiet; there’s no cloud of snow like with an avalanche, making it difficult to see. There’s no way to predict them ... sometimes there’s a seismic signal.”
Tucker said it was unusual to see photographic evidence that was obtained so soon after a geologic event in a remote area. He said the debris flow was reported by Corey Vannoy of Bellingham, who summited with 10 mountaineers in two parties June 4-5. He emailed images that clearly show the point below Sherman Peak near the crater where snow and ice broke free and traveled downhill.
“It was massive, the size of this debris flow. We almost couldn’t believe it. We were dumbfounded,” said Vannoy, a chemical engineer at the BP refinery near Ferndale. “This is a ridiculous amount of debris.”
His party made their ascent via the east-facing Boulder Cleaver route because it is more challenging than the more popular approaches up Easton Glacier from the south or the Coleman-Deming glaciers from the west slope, where Vannoy first climbed Mount Baker.
Tucker said casual observers might be able to see the debris flow from the turnout at the bridge where Baker Lake Road crosses Boulder Creek, site of a sharp turn.
“But the best viewing will be from across Baker Lake, up Anderson Lake Road,” Tucker said. “That road has a very good view of the entire eastern flank. (The road) should be pretty much melted out by now.”
He said a review of seismic signals pinpointed the timing of the avalanche and debris flow to 2 p.m. May 25.
This article has been updated to note that the debris flow did have a seismic signature and to update the research center’s contact information.