Monday, September 13, 2010

Mount St Helens :: 30 Years Later

At 8:32 am on May 18th, 1980 a magnitude 5.1 earthquake “shook the ground beneath Mount St. Helens in Washington state, setting off one of the largest landslides in recorded history - the entire north slope of the volcano slid away. As the land moved, it exposed the superheated core of the volcano setting off gigantic explosions and eruptions of steam, ash and rock debris. The blast was heard hundreds of miles away, the pressure wave flattened entire forests, the heat melted glaciers and set off destructive mudflows, and 57 people lost their lives. The erupting ash column shot up 80,000 feet into the atmosphere for over 10 hours, depositing ash across Eastern Washington and 10 other states.” - - from The Big Picture which has a fantastic collection of photos of the volcano and its 1980 eruption.

The western side of Mount Saint Helens as seen from the Visitor Center at Silver Lake, 46 road-miles away.

From a viewpoint on the north-northwest side.

Clouds covered the upper half of the volcano for the entire afternoon with an occasional break, which briefly revealed the peaks. This, and the remaining photos were taken from the Johnston Ridge Observatory. Named for David A. Johnston, a volcanologist on duty nearby on that fateful day. His last words were “Vancouver, this is it!”

The lateral blast exploded to the north toward what is now Johnston Ridge and, quite literally, destroyed everything in its path.

The mountains and valleys were tall old-growth forest. Now all that remains are a few denuded logs lying about like pick-up-sticks.

A park service sign nearby tells a tale of the blast as “spoken” by this stump: “Step up and look at me carefully. Notice my shattered trunk, my missing top. I once stood 150 feet tall, surrounded by a beautiful forest of green and growing trees. When the blast exploded sideways out of the mountain, it plowed through the debris avalanche and swept across the landscape, picking up and carrying large chunks of rock, ice, and splintered wood.”

“Within a minute, I was struck and scoured by the stone-filled wind. My bark and branches were stripped and scattered toward the edge of the blast zone, 17 miles away. As trees that had stood for hundreds of years crashed around me, my upper trunk strained, then shattered in the nearly 700 mph winds. Only a small part of me remains as evidence of the blast's power.”

Down in the valley, the blast dumped 680 feet of debris, filling Spirit Lake to the east with logs and ash.

Johnston Ridge was completely denuded. Spirit Lake lies beneath the far ridge at left-center and St. Helens rises up from the valley on the right.

The early evening light emphasizes the ridges and the gulleys now being carved out by the flow of water.

Another view of cloud shrouded St. Helens from Johnston Ridge in the early evening. All photos were taken on Sunday, September 12th.

The Johnston Ridge Observatory, which is 5 ½ miles from the crater, has some really nice exhibits as well as a 16-minute movie about St. Helens. If you've never been there, it is well worth the 60-mile drive off of Interstate 5 on State Road 504.

A couple of the many websites about Mount St. Helens:

1 comment:

  1. We were at Mt. St. Helens a couple of years ago and just amazed at the power of the blast. I have so been enjoying your travels. Babs

    ReplyDelete

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