May 09, 2009
May 27, 2010
The Mt. St. Helens National Monument was established in 1982 and visiting it reminds us of both the destructive and recuperative powers of Mother Nature. Some amazing facts we learned:- The eruption leveled 230 square miles of forest in less than 10 minutes
- The mountain lost 1300 feet of height and 0.6 cubic miles of total volume
- The eruption began with a massive landslide that buried 14 miles of river valley to a depth of 150 feet.
- Trapped magma and gas were released, producing a sideways explosion (lateral blast) of hot rock and ash, killing trees up to 17 miles north of the volcano.
- Ash erupted 15 miles high above the crater for nine hours.
Through film and interpretative displays at the Johnston Ridge Observatory (the primary Visitor Center that also serves as a volcanic monitoring station), we saw before-images of the previously beautiful mountain, the eruption and subsequent lateral blast, the resulting destruction, and harrowing stories of survival. But we also observed how nature is restoring the area – for example, with new lakes that formed, now clear and supporting both plant and fish life; reforestation; and natural resurgence of vegetation. Speaking of reforestation, we were surprised to learn of efforts by the Weyerhaeuser Company, which was the largest landowner in the area due to its forest acreage for logging, to reforest the area. Over a six-year period (1981-1987), 18 million seedlings were hand-planted over 45,500 acres. They also led a huge salvage effort of downed or seared trees. One of their signs indicated that they spent $9 million on this effort. Eventually, their effort will support logging again, but in the meantime, it was good to see young forests where there was once devastation.
Within the crater on the mountain, a lava dome built up from 2004-2008 due to ongoing eruptions and is now taller than the Empire State Building, replacing 7% of the former peak. Last year, the lava dome building stopped and it is considered dormant (for now!). Unfortunately, our weather luck had not held up and while we were here, it was cloudy and hazy. So, we were not able to get clear views of the crater and the lava dome. We've included some anyway so you can get the general idea..
Our next stop was another volcanic Cascade mountain, Mt. St. Helens. Mt. St. Helens erupted (more like exploded) on May 18, 1980, triggered by a 5.1 magnitude earthquake. I remembered the newspaper and TV coverage on the devastation that occurred, but of course not in detail. The effects were not felt in Tallahassee where I lived and like all big news events, the impact faded for those of us not directly impacted. Jim, however, had visited Mt. St. Helens the year after the eruption and remembers the bleakness of the landscape and the large scope of devastation.