300 miles?? Were you living in Washington then? Where? My grandparents farm was about 120 miles from Mt. St. Helens, in Oregon near a small town of St. Helens, Oregon. They both heard the explosion and saw the ash clouds rising up. The got so much ash that my grandfather had to climb the roof and shovel off the ash before it caused the roof to cave in. The ash was very, very heavy. On my next visit (I lived in CA at the time) they gave me a small round margarine tub of the ash--it must have weighed a couple of pounds--very heavy. Even at that distance they were cautioned to wear a mask when going outside. Inhaling that ash was a deadly thing to do.
I was in Montana, just east of the Idaho border. I actually checked the distance before my first post on my old "Roads And Trips" program that gives me the option to measure distance in a straight line. It is 300 miles. I remember on the news it was reported that the explosion was heard as far away as some Central Washington town, maybe Yakama (can't remember now), which would be like 60 miles away from St Helens. I felt like I wanted to call the News channel, and tell them I heard it and I was more than 4 times farther away. What a gyp. But of course I didn't bother.
I thought it was a mine about 20 miles from my house using dynamite, and I remember thinking they were probably dynamiting on a Sunday when the workers were gone. The blast was a long thunder like rumble that lasted maybe 30 seconds. Of course it was fairly well corrupted by the time the sound got to me.
Our ash, as you might guess was nowhere near as heavy as yours. A margarine tub would have weighed ounces. and our accumulated depth was more like a heavy dusting, but it was everywhere. It may have been a quarter of an inch in some places.
