New study on the Bonneville landslide

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Don Nelsen
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New study on the Bonneville landslide

Post by Don Nelsen » June 27th, 2022, 2:49 pm

Interesting info about the slide that posits a quake at Mt. could have triggered the slide, not a subduction zone quake.

https://katu.com/news/local/new-researc ... gods-slide
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adamschneider
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Re: New study on the Bonneville landslide

Post by adamschneider » June 27th, 2022, 10:45 pm

Wow, that article is way better (and more detailed) than I'd expect from a TV news station.

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retired jerry
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Re: New study on the Bonneville landslide

Post by retired jerry » June 28th, 2022, 5:35 am

yeah, really. TV news usually just has some superficial stuff with some details wrong, like the name of a creek or mountain. That article is pretty good.

Has anyone seen the Gate Creek fault? Four to five feet high - that should be pretty easy

Image

It looks like the fault goes through the south defiance trailhead and the wyeth trail crosses the fault

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drm
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Re: New study on the Bonneville landslide

Post by drm » June 28th, 2022, 6:36 am

I had always thought that the slide that created the temporary bridge was dated to the 1700s. In our climate I didn't think that those trees would last that long, they should decompose before centuries go by. But this article says the slide is dated to t he 1400s.

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bobcat
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Re: New study on the Bonneville landslide

Post by bobcat » June 28th, 2022, 8:30 am

drm wrote:
June 28th, 2022, 6:36 am
In our climate I didn't think that those trees would last that long, they should decompose before centuries go by.
The natural agents that promote decay of woody material are not present underwater (lack of oxygen). Much of the city of Venice sits atop alder and oak pilings that are at least as old as the Bonneville drowned trees.

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drm
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Re: New study on the Bonneville landslide

Post by drm » June 28th, 2022, 11:11 am

bobcat wrote:
June 28th, 2022, 8:30 am
drm wrote:
June 28th, 2022, 6:36 am
In our climate I didn't think that those trees would last that long, they should decompose before centuries go by.
The natural agents that promote decay of woody material are not present underwater (lack of oxygen). Much of the city of Venice sits atop alder and oak pilings that are at least as old as the Bonneville drowned trees.
Why do you think there is no oxygen underwater? I found this online:
Rivers and streams tend to stay near or slightly above 100% air saturation due to relatively large surface areas, aeration from rapids, and groundwater discharge, which means that their dissolved oxygen concentrations will depend on the water temperature ¹
.

So maybe the dams have resulted in calm water that limits oxygen levels, but they are very recent in comparison to this event. I certainly have read of cases of sunken wooden boats surviving a long time in cold and deep water.

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Re: New study on the Bonneville landslide

Post by bobcat » June 28th, 2022, 1:39 pm

No oxygen for the fungi that break down the cellular material. When wood is submerged, all of the air it contains is expelled.

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Don Nelsen
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Re: New study on the Bonneville landslide

Post by Don Nelsen » June 29th, 2022, 11:26 am

bobcat wrote:
June 28th, 2022, 1:39 pm
No oxygen for the fungi that break down the cellular material. When wood is submerged, all of the air it contains is expelled.
I've kayaked on Clear Lake off of Hwy 26 south of Santiam Pass. It's amazing to see the trees sticking up from the bottom knowing they were inundated when the lake formed about 3000 years ago. Granted, clear lake has exceptionally pure water and is always cold, but, still, 3000 years and still not rotted away!
https://www.onlyinyourstate.com/oregon/ ... st-oregon/

dn
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retired jerry
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Re: New study on the Bonneville landslide

Post by retired jerry » June 29th, 2022, 11:36 am

That's like Spirit Lake pre eruption

The bottom was covered with big trees from the previous eruption

The water was pretty clean and cold

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