Allegations: Oregon Not Forthcoming With Landslide Hazard Information
A massive rockslide closed a busy interstate route last week near the border between Tennessee and North Carolina in Pigeon River Gorge. This area has had landslide problems in the past. In 1997 a rockslide in the same area closed the freeway for approximately 3 months. (Photo from Landslides Under a Microscope Blog, original source not cited)
I have yet to see volume estimates, but The Charlotte Observer quoted a highway patrol officer who was at the scene:
He said the roadway is covered by a gigantic mound of debris, from pebbles up to house-sized boulders. The pile is 40 to 50 feet high, Williamson estimated, and hundreds of feet long.
More info and video after the break. […]
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Copyright © 2007-2020 by Randy Post
Clatskanie Landslide
Dear geo blogger,
My take on this slide is that the old railroad crossing or road crossing that held up the water for the Clatskanie Event on or about Jan 11, was not “put to bed”. The crossing should have been destroyed and the abutments pulled out of the channel. The slide volume and extent of travel of the subsequent debris flows would have been much smaller and shorter.
I served for a year as an ERFO Hydrologist at the Detroit Ranger Station, up the Santiam Canyon from Salem in 1997 and 1998. An about-to-retire civil engineer, Bill Day, used the “put to bed” term and practice. He also said something else that was useful, “it takes trees to be twenty years old or more before their root systems hold back natural landslides. The trees on the reforested property above the Clatskanie debris flow section were not that old.
I agree with Bill Burns and, to reinforce his statements, I like what he said about the recent spate of landslides.
John Rehm
Registered Geologist G1137
Salem, Oregon
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Note: This is a Opinion based on literature (Dryness, c. 1964), my MS Thesis published on the Rutgers University Geosciences website, and professional experience under registered engineer supervision by Bill Day (1997-1998 (just in case OSBGE is reading this)
Put to bed
Thanks for your insights John. I’ve never heard the term “put to bed” before, but I couldn’t agree with you more. And the factoid about tree root systems seems like a very useful rule of thumb. — Randy Post (aka Rockman)