Wednesday, July 18, 2012

Massive Landslide Covers Glacier in Alaska

The Johns Hopkins Glacier in Glacier Bay National Park, Alaska

On June 11 a massive amount of rock and ice was let loose from Lituya Peak in Glacier National Park, Alaska. The resulting run out on the landslide went 5.5 miles down valley and covered the Johns Hopkins Glacier. The slide even registered as a 3.4 magnitude earthquake event on nearby seismographs. You can read a news story about this event here:

I also received a pdf composed by Martin Geertsema, PhD, with photo's taken by pilot Drake Olsen. These are included below.

 Here are the seismograph readings from three nearby Canadian stations on June 11

Cartoon from Google Earth showing the shource area of the slide and the extent of the resulting run out

Photograph by pilot Drake Olsen taken in July. I have traveled in Glacier Bay a lot and can attest to the fact that one rarely gets a view this good of the surrounding mountains. That is why the event was not recorded visually until July.

 Closer view of the source area on Lituya Peak

The width of the slope failure is over 600 feet with lots of ice from the shoulder of the mountain mixed in with the rock and boulders

A view down valley of the resulting debris field. Note that the air column in front of the slide pushed fine debris (sand and silt) up onto the nearby ice field.

This air blast took debris over 1,500 feet up the slope! To read about another exciting geologic event from this area in 1958, see the link here and another one here.

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