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Five Years Later - The Oso (SR 530) Landslide in Washington

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  • Five Years Later - The Oso (SR 530) Landslide in Washington

    Five Years Later - The Oso (SR 530) Landslide in Washington

    https://www.usgs.gov/news/five-years...ience_products

    Scary pics, too...

    This was the one that killed ~43 folk and also flooded Steelhead Haven via debris dam...

    quote:
    USGS interviews with eyewitnesses and analyses with dynamic landslide models indicate the landslide’s average speed was about 40 miles per hour. New volume estimates of the landslide using lidar-derived maps collected after the landslide reveal that, by the time the event had ended, the landslide had moved about 19 million tons of sand and till, and had covered approximately one-half square mile. That amount of material would cover approximately 700 football fields 10 feet deep.

    The slide dammed the North Fork Stillaguamish River to a depth of as much as 25 feet, forming a temporary lake 2.5 miles long, which flooded houses and other structures in Steelhead Haven. In the 6-8 weeks after the landslide, and with some initial assistance from responders using a dredge, the river slowly eroded a channel through the landslide debris. This cut the river bed back to near its pre-landslide elevation and effectively drained the remaining excess water by the middle of May.
    /
    Be NOT There...
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