Trees and landslides

You know the Oso landslide? The collapse of a rain-sodden slope that buried a lot of houses, vehicles, animals, and people in a small town north of Seattle two weeks ago?

It’s been reported heavily in the local media, but as a natural disaster and human tragedy, not as something that had been predicted and warned about for decades. Well guess what – it was predicted and warned about decades ago.

Rain is the fuel for landslides in wet western Washington. The tall trees of the Evergreen State help hold the ground together, not just with their roots, but also by soaking up rain before it goes deep underground. That’s why the state essentially prohibits clearing of forests in places where groundwater can pool beneath a landslide zone.
Kennard: “The clearing just makes it much more vulnerable for when you have a wet winter like now.”
Kennard works at Mt. Rainier National Park now. But in the 1980s he worked for the Tulalip Tribes north of Seattle. Even back then, tribes and state officials knew the Oso site had a long history of landslides large and small. 26 years ago, Kennard helped the tribes stop a clearcut on the same slope that gave way last week. The tribes saw it as a victory for the salmon they depend on in the Stillaguamish River at the base of the muddy slope.
Kennard: “We considered it a victory because the Department of Natural Resources, who has say over these things, this was the first time to our knowledge that they actually prohibited clearcutting of trees because there seemed to be a connection with landslides.”

And they prohibited it on the Hazel slope, which is the slope that gave way and fell on Oso two weeks ago, killing a lot of people and animals. Gosh gee what a coincidence.

So, on the night of the latest slide, Kennard was surprised when he looked up the area on Google Earth. He saw an aerial photograph with a clearcut from 2005 right at the edge of the landslide zone.
Kennard: “I thought, whoa, that seems to be awfully close.”
Aerial photos taken of the Oso slide last week show a wall of exposed earth hundreds of feet high, almost directly below that 2005 clearcut.
State officials say the cut they approved was safe: it was just outside the no-logging area intended to keep groundwater from building up. But those aerial photos also show that the seven-acre clearcut crossed the line. Here’s Washington State Forester Aaron Everett.
Everett: “It appears, though we continue to investigate, that there’s been an intrusion into the no-harvest area.”
That intrusion apparently happened at the hands of the landowner, a small timber company called Grandy Lake Forest Associates. But the company has not responded to interview requests.

Brilliant, isn’t it? Grandy Lake Forest Associates got a few more trees and so a few more dollars – and a bunch of people in Oso got killed.

That 2005 clearcut? The state allowed it right on the boundary of a no-logging zone that didn’t reflect the latest scientific information. State-funded research from eight years before the clearcut showed the groundwater danger zone clearly overlapping with the area the state OK’d for clearcutting. Everett says the DNR is investigating what happened.
Everett: “The protections that the department puts in place to ensure that timber harvest do not contribute to landslide hazards are rigorous and are designed to protect public safety and natural resources. It’s a difficult thing to talk about in the face of a tragedy like this.”
Geologists say identifying where groundwater moves beneath a landslide zone is hard to do precisely.
Here’s geomorphologist Paul Kennard:
Kennard: “Perhaps what is sort of the legal definition of the groundwater recharge area is actually a small part of the real groundwater recharge area. All that area has been cut and it takes decades to recover.”
Kennard urges more cautious landuse anywhere near one of these deep-seated landslide zones.
But geologists also urge people not to jump to conclusions about the role of one small clearcut in 300-acre landslide. They say detailed study of this slide is needed before concluding how much of a role, if any, the recent clearcutting played.

Ok. Don’t jump to the conclusion that it was for sure logging that caused the landslide. Ok. But you know what? It seems like the kind of thing where you err on the side of caution, by a wide margin. You have what a geomorphologist considers a slide-prone hill right above a town. That seems like one stand of trees you just leave alone.



  1. mfd1946 says

    “You have what a geomorphologist considers a slide-prone hill right above a town. That seems like one stand of trees you just leave alone.”

    Irrefutable logic, it would seem. Then the chance for some person or entity to make really big money enters the scene, trumping any and all forms of logic.

    An old and still popular saying declares, “Money talks and bullshit walks.” It needs amending to “Money talks and everything else walks.” Because in too many sectors of our world, anything that isn’t money is bullshit. And so a few nobodies had to die. Anecdotal. Business as usual need never change. The true adults of the world have spoken.

  2. says

    geologists also urge people not to jump to conclusions about the role of one small clearcut in 300-acre landslide

    This geologist googled *oso before and after* and it caused me to jump to a conclusion.

  3. Seth says

    This reminds me of a conversation I had with a European friend of mine recently; she’s observed that, in Europe, the authorities tend to prohibit a chemical or a practice until it’s conclusively proven not to be harmful to humans. The North American practice is evidently that something is only banned when it is conclusively and irrefutably proven to be disastrously harmful, and even then companies can get around the exclusions almost willy-nilly. Which is why, e.g., Kraft Dinner uses turmeric and other spices in Europe, whereas in North America it gets its yellow colouring from a chemical that may well be carcinogenic.

    It all comes down to money. Money is the only kind of people the American government seems willing to protect.

  4. lpetrich says

    Skepticblog » Oso tragic, Oso foolish — great title.

    Among the victims of that landslide was likely a certain Thomas Satterlee, who objected to warnings about landslides as big-government nannying. He supported the Sovereign Citizen movement, in which one declares one independent of the Federal and state governments, and thus not subject to taxes or disliked laws. He wanted the region around Oso to have that status, but he lost in court.

  5. says

    Wow – there’s a bitter irony for you.

    I kind of figured that was the case – I figured many locals would see it as a matter of jobs. And the media coverage has – as far as I’ve seen – totally ignored the issue, preferring to treat it as a Tragedy that Just Happened Somehow.

  6. lpetrich says

    But did they have to live in the path of a likely landslide in order to have whatever jobs they had? I think that more people ought to do what the inhabitants of Valmeyer, IL had done and move out of the way of known hazards. Their infrastructure would have to move with them, and I have no objection to subsidizing such moves.

    Thomas Satterlee was one of the main opponents of a 2006 law limiting development in hazardous areas. Their reason was that governments ought not to “meddle in the private affairs of residents”. But the politicians may not want to play Russian Roulette with the infrastructure that they finance and manage.

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