On May 18, 1980, in southwestern Washington, Mount St. Helens erupted, detroying more than 150 square miles of prime Northwest forest, Spirit Lake, etc. and sending ash several miles into the air. The ash cloud went eastward, blanketing Yakima (WA), turning 12:00 noon into nighttime conditions. The cloud moved across eastern Washington, Idaho, Montana, and beyond. I had firends from Billings tell me about the ash covering their lawns.
There are a number of Web sites about Mount St. Helens that can give people more information--more accurately--than I can. People can also access information from sites devoted to the state of Washington and to affected counties--Clark, Lewis, and Cowlitz. The US Geological Volcano Observatory is located in Vancouver, Washington, and has a Web site. Not only can people get information about past eruptions of Mount St. Helens, but they can find out about current conditions of the mountain (it is constantly being monitored). They can also find out about other volcanoes around the world.
The Mount St. Helens National Volcanic Monument is about an hour and half drive from Portland (about 2 hours from Seattle) and makes a pleasant, intriguing outing. The are several visitor's centers, each one dealing with a different aspect of the eruption. The one at Silver Lake (the one nearest to Interstate 5) has the most information about the eruption, mud flows, the aftermath, geological information, etc. The Coldwater Ridge Center concentrates on the recovery--how some animals and plants survived, the recovery of the area (trees, plants, animals are all growing and coming back at noticeable rates). Coldwater Lake has fish in it. There are numerous hiking trails. Everytime I go back, I see something different; things have grown back that much more.
The most exciting center, I think, is the one on Johnston Ridge: it has volcano monitoring equipment and one can look directly into the crater, which is only five miles distant. However, weather must be cooperative, which isn't always. After all, this is the Pacific Northwest, which rain is a constant, and the mountains themselves are known to create their own weather.
however, this is still interesting, and these weather conditions are also a part of the reshaping and revitalizing of Mount St, Helens and its environs.