I was 2 years old when St Helens blew, having lived in Seattle for a majority of my life I've heard all about it. heres some quick facts copy and paste style
May 18th, 1980, 8:32 am (PDT). Eruption was triggered by a 5.1 earthquake centered beneath the mountain.
MSH was 9,677 feet before the eruption and 8,363 feet after. 1,314 feet was removed by the May 18th eruption.
The largest landslide in recorded history swept down the mountain at speeds of 70 to 150 miles per hour and buried the North Fork of the Toutle River under an average of 150 feet of debris. Some areas are covered by as much as 600 feet. In all, approximately 23 square miles of material was removed from the mountain.
The lateral blast swept out of the north side of MSH at 300 miles per hour creating a 230 square mile fan shaped area of devastation reaching a distance of 17 miles from the crater. With temperatures as high as 660 degrees F and the power of 24 megatons of thermal energy, it snapped 100 year old trees like toothpicks and stripped them of their bark.
The snow on MSH that was not instantly flashed to steam by the heat, melted and formed large mudflows that destroyed 27 bridges, 200 homes, 185 miles of roadway, and 15 miles of railway.
The massive ash cloud grew to 80,000 feet (18 kilometers) in 15 minutes and reached the east coast in 3 days. Although most of the ash fell within 300 miles of the mountain, finer ash circled the earth in 15 days and may continue to stay in the atmosphere for many years.
57 people were killed as a result of the eruption. Of these, 21 bodies were never recovered from the blast zone.
7,000 big game animals, 12 million Chinook and Coho salmon, and millions of birds and small mammals are believed to have died in the eruption.
The list goes on.....
Dan you are correct I have taken a quite a few flights on alaska air right over St helens and Mt Rainer which is considered to be the most dangerous volcano in the country.
Mt Rainer from alaska airlines window seat one morning