So, the current weather alerts for Bellevue include a "Volcanic Activity statement" of "resuspended VA due to high winds," and at the end of the statement the assurance that no eruption is occurring.
"VA" turns out to be volcanic
ash, not activity. A bit of googling got me a similar report, based on satellite activity, from Alaska last year. That was ash from the
1912 eruption of Katmai:
http://cimss.ssec.wisc.edu/goes/blog/archives/13992. I'd sort of assumed that volcanic ash either washed away, was buried, or became cemented together within a few years. That's not the kind of thing you get in the basic "how a volcano works" explanations, which tend to focus on the time before, during, and right after the eruption. Or, with Mount Saint Helens, discussion of the gradual return of different plants, animals, and other life forms to the area around the volcano, and the formation of a new, small glacier on the mountain.
(Seattleites probably won't have seen that warning: the "cities affected" in this area are all on the East Side, including Renton, Bellevue, Redmond, Kirkland, Bothell, and Issaquah. Google found the same warning text for Ashland, Oregon, which is covered by a different National Weather Service office.)Seattle and other bits on that side of the lake too, as of Friday morning.