{"id":43739,"date":"2023-05-25T07:07:09","date_gmt":"2023-05-25T07:07:09","guid":{"rendered":"https:\/\/blogs.agu.org\/landslideblog\/?p=43739"},"modified":"2023-05-25T07:07:09","modified_gmt":"2023-05-25T07:07:09","slug":"mount-saint-helens-1","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2023\/05\/25\/mount-saint-helens-1\/","title":{"rendered":"The 14 May 2023 debris flow at Johnston Ridge Observatory Access Road, Mount Saint Helens"},"content":{"rendered":"

The 14 May 2023 debris flow at Johnston Ridge Observatory Access Road, Mount Saint Helens<\/strong><\/p>\n

Guest post by loyal reader Funkenbeachin<\/h4>\n

On the evening of 14 May 2023, rapid snowmelt in response to unusually warm weather contributed to the occurrence of a large debris slide [46.2807, -122.1906] and debris flow that damaged the access road, State Route 504 [46.2822, -122.1952], to the Johnston Ridge Observatory at Mount Saint Helens in Washington, USA.\u00a0 Twelve people and a dog were evacuated by helicopter the following day.<\/p>\n

King 5 Seattle television provided helicopter views of the debris slide and damage in the channel of South Coldwater Creek, tributary to the Toutle River: \u00a0https:\/\/www.youtube.com\/watch?v=aSX1Z1KBN54<\/a><\/p>\n

The author has put together a video of the topography of the site using Lidar and aerial imagery, which also includes meteorological data at the end: \u00a0https:\/\/youtu.be\/uRPwXvy-uOI<\/a><\/p>\n

The debris-slide overlies the Spirit Lake Outlet Tunnel, designed to control overflow of Spirit Lake.\u00a0 The 12 meter diameter tunnel was drilled from the SR-504 bridge crossing [46.2822, -122.1952] to a 12 meter deep shaft on the shore of the lake [46.276447, -122.162624].<\/p>\n

There is a gallery of images of the landslide, which includes the source area, on the WSDOT Flickr page<\/a>:-<\/p>\n

\"The

The source area of the Mount Saint Helens landslide on 14 May 2023. Image by WSDOT via Flickr<\/a>.<\/em><\/p><\/div>\n

.<\/p>\n

Whilst this image shows the damage to the road:<\/p>\n

\"Damage

Damage to the road after the Mount Saint Helens landslide on 14 May 2023. Image by WSDOT via Flickr<\/a>.<\/em><\/p><\/div>\n

.<\/p>\n

Useful references<\/h4>\n

Grant, G., Major, J., Lewis, S., 2017, The Geologic, Geomorphic, and Hydrologic Context Underlying Options for Long-Term Management of the Spirit Lake Outlet Near Mount St. Helens, Washington. Pacific Northwest Research Station General Technical Report, PNW-GTR-954. \u00a0https:\/\/www.fs.usda.gov\/pnw\/pubs\/pnw_gtr954.pdf<\/a><\/p>\n

Watts, A., 2019, The Spirit Lake dilemma: Engineering a solution for a lake with a problematic outlet. Science Findings, Issue 218, Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station.
\nhttps:\/\/www.fs.usda.gov\/pnw\/sciencef\/scifi218.pdf<\/a><\/p>\n

.<\/p>\n

Acknowledgement<\/strong><\/h4>\n

Many thanks to Ken for pulling this together at a very busy time for me, and to others for contacting me about it.<\/p>\n","protected":false},"excerpt":{"rendered":"

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