Erosion of tephra from the 1980 eruption of Mount St. Helens

Research Article| July 01, 1986 Erosion of tephra from the 1980 eruption of Mount St. Helens BRIAN D. COLLINS; BRIAN D. COLLINS 1Department of Geological Sciences and Quaternary Research Center, University of Washington, Seattle, Washington 98195 Search for other works by this author on: GSW Google Scholar THOMAS DUNNE THOMAS DUNNE 1Department of Geological Sciences and Quaternary Research Center, University of Washington, Seattle, Washington 98195 Search for other works by this author on: GSW Google Scholar Author and Article Information BRIAN D. COLLINS 1Department of Geological Sciences and Quaternary Research Center, University of Washington, Seattle, Washington 98195 THOMAS DUNNE 1Department of Geological Sciences and Quaternary Research Center, University of Washington, Seattle, Washington 98195 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1986) 97 (7): 896–905. https://doi.org/10.1130/0016-7606(1986)972.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation BRIAN D. COLLINS, THOMAS DUNNE; Erosion of tephra from the 1980 eruption of Mount St. Helens. GSA Bulletin 1986;; 97 (7): 896–905. doi: https://doi.org/10.1130/0016-7606(1986)972.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Erosion of tephra on hillslopes north of Mount St. Helens was measured at intervals of several months between 1980 and 1983 using large arrays of stakes. Rill erosion was initially greater than sheetwash, but its importance decreased comparatively quickly. Both rill erosion and sheetwash decreased by one to two orders of magnitude over the three-year period, because a stable rill network developed and more permeable and less erodible substrates were created or exposed. The decrease occurred prior to recovery of plants. The causes for the rapid decline in erosion at Mount St. Helens explain patterns of erosion following several other recent tephra eruptions.Basin-wide annual rates of erosion were computed by mapping the surface cover, the hillslope gradient, and the texture and thickness of tephra and by using statistical relations developed between them and erosion rates. Annual erosion decreased from 26 mm between May 1980 and May 1981 to 1.8 mm between May 1982 and May 1983. Projecting this rate of decline into the future indicated that only about one-sixth of the tephra on hillslopes will be removed by water erosion before soil creep and other forms of mass wasting again dominate hillslope evolution. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.