September 29, 2010

We made the 2-hour drive to the north side Mount St. Helens, and it was definitely worth the trip! We went to the Johnson Observatory, which is about 5 miles away from the mountain. It has a lot of information, as well as a spectacular view. The “before” photos of the area show a beautiful, classic cone-shaped mountain surrounded by old-growth forest. Oddly enough, before 1980 although most of the mountain was owned by the Forrest Reserve, the top of the mountain was owned by Burlington Northern. When the crazy seismic activity started in 1980 reporters and curiosity-seekers arrived in droves, so Burlington Northern turned control of the mountain top over to the Forest Reserve, who could better keep people out.

Mount St. Helens is really beautiful and impressive. The whole 5 miles of plains in front of it are covered by the landslide that was part of the 1980 eruption.



















In that eruption the top and most of the north side of the mountain were part of the massive landslide which moved about 90% of the mountain's mass. That triggered super-heated pyroclastic flows (powerful explosions of gas and rocks). The nearby trees didn't burn; there wasn't enough air around them during the eruption. The heat caused the trees to explode from the inside. Trees that were far enough away to avoid exploding (maybe between 5 and 15 miles) were snapped off and flattened by the tremendous force. In the picture below, Randy is on the road at the bottom of the frame.















After the pyroclastic flows came huge ash clouds. There was no big lava flow but the landslide was so hot that the ground became sterilized – nothing was left alive in those 5 miles. The area was designated as a National Monument to let it recover naturally and scientists are surprised how quickly it is recovering. The landslide area has significant ground cover now and a big herd of Roosevelt Elk have moved in.

Since the 1980 eruption, a big dome has been forming in the center of the crater. It’s completely surrounded by a glacier – probably the newest glacier in the world because it didn’t exist before 1980. The plains get 10-14 feet of snow each winter and the mountain probably gets more. The crater rim protects the glacier from melting, as do the rocks that crumble and fall onto it. Because it's covered in rocks, the glacier is almost completely black. I couldn't to get a clear picture, but the photo below is the crater with the new dome in its center, and lying across the front of the dome is the black glacier. With binoculars we could see that most of what looks like snow on the dome are active steam vents.