| Abstract: | A slope stability analysis on the South Fork Castle Creek debris avalanche blockage, near Mount St. Helens, Washington, was conducted to determine the likelihood of mass failure of the blockage and resultant breakout of South Fork Castle Creek Lake. On the basis of material properties, groundwater levels, and seismic history of the blockage, slope stability with and without earthquake-induced forces was determined. Results indicated that the blockage will not fail from gravitational forces at September 1983 groundwater levels. An increase of 25 feet or more in water levels could cause local failures, but massive failure of the blockage is improbable. Blockage slopes are potentially unstable for present and higher water levels if an earthquake with magnitude greater than 6.0 should occur. Retrogressive slope failures are possible, but lowering of the blockage crest below lake level and consequent lake breakout are considered remote. Significant earthquake shaking could cause cracks in the blockage that might facilitate piping. (USGS) |
| Genre: | USGS Numbered Series |
| ProdID: | 38516 |
| Citation Author: | Meyer, William; Sabol, M. A.; Glicken, H. X.; Voight, Barry |
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| Citation Language: | ENGLISH |
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| Citation Phsyical Description: | 42 p. |
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| Citation Series: | Professional Paper |
| Citation Series Code: | PP |
| Citation Series Number: | 1345 |
| Citation Search Results Text: | The effects of ground water, slope stability, and seismic hazards on the stability of the South Fork Castle Creek blockage in the Mount St. Helens area, Washington; 1985; PP; 1345; Meyer, William; Sabol, M. A.; Glicken, H. X.; Voight, Barry |
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| Citation Year: | 1985 |
| Type: | citation/reference |
| Text: | The effects of ground water, slope stability, and seismic hazards on the stability of the South Fork Castle Creek blockage in the Mount St. Helens area, Washington; 1985; PP; 1345; Meyer, William; Sabol, M. A.; Glicken, H. X.; Voight, Barry |
| URL (THUMBNAIL): | http://pubs.usgs.gov/pp/1345/report-thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/pp/1345/report.pdf |
| Date Other: | Sat, 1 Jan 1994 00:00 -0600 |
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http://pubs.er.usgs.gov/publication/ofr84624
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