Increased heat emission from Mount Baker, Washington

In late afternoon on March 10, 1975, Roy Ashe, operator of the Upper Baker Dam at the Baker Lake hydroelectric reservoir, reported than an unusually large dark gray plume of vapor was rising above the rim of the Sherman Crater near the top of Mount Baker, 21 km upstream. A flurry of aerial observations the following day noted distinct changes from previously known fumarolic activity in the ice‐covered crater. New fumaroles, ice pits, semicircular crevasses, and ponded water in the crater had appeared, as well as a thin dusting of gray debris 100 to 300 m outside the crater. The apparently sudden change in the thermal regime of Mount Baker was obvious as well as ominous.