Thursday, July 4, 2013

Earthquake of 1959

Hilgard lodge fell into Hebgen Lake
About 35 miles northwest of West Yellowstone is the site of a huge landslide in Madison Canyon. The great earthquake of 1959, between 7.3 and 7.5 on the Richter scale, caused 80 million tons of rock and debris to break off one side and slide at a speed of 100 mph into, and across, the canyon in 20 seconds! The slide buried everything in its path and the hurricane force winds it caused tossed cars and campers around. The slide hit a campground burying 19 people and injuring many more. Further up the canyon other people were injured and killed from falling debris, collapsing roads, and literally being blown away by the wind.

Earthquake Lake natural dam
See slide area on left
The slide blocked the Madison River creating Earthquake Lake, or as they call it here, Quake Lake. The water backed up rapidly causing fear of what would happen to the Hebgen Lake dam upstream as well as what would happen to the slide area as pressure from the backed up water became greater. These fears forced one of the largest-ever mobilizations of the Army Corps of Engineers to quickly cut a spillway to release water in less than 3 weeks. 
Highway 287 fell into Hebgen Lake
Today, there are a number of interpretive signs and pullouts along highway 287 which runs along Hebgen Lake. There are still remains of buildings that fell into the lake and you can walk along the old highway to the point where sections of it also fell into the lake.  

Right on top of the slide that formed Quake Lake there is a visitor center, interpretive signs and lookouts where you can take in the magnitude of what happened.
From top of slide to other side where
it came from. Look in lower right corner
to see where the two large boulders in
the next picture came from

Quake lake from top of slide.
Two large boulders carried across at
100 mph now rest here
During our touring of Yellowstone National Park we have seen a number of references to thermal activity stopping or starting when this earthquake occurred.

Below are a couple of links that give a few more details.

See the right side of this sign for
a pictorial description of the slide

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