Sedimentology and clast orientations of the 18 May 1980 southwest- flank lahars, Mount St. Helens, Washington
Three lahars that resulted from the flow transformation of an inflated pyroclastic surge caused by ejected lithic debris and hydrothermal water during the cataclysmic Mount St. Helens eruption of 18 May 1980 deposited about 1 x 106 m3 of massive, poorly sorted, poorly graded volcaniclastic sediment on the SW flank (SWF). Downflow changes in mean grain size and sorting occur only in the coarse fraction of the deposits larger than a critical diameter of about 4mm, and occur only in the basal portion of the deposits; both mean grain size and sorting coefficient increase slightly with distance. The deposits show weak inverse grading with respect to mean grain size and exhibit a weak trend of upwardly poorer sorting, but lahar clast fabric may be more complex and variable than previously suggested.
|Publication Subtype||Journal Article|
|Title||Sedimentology and clast orientations of the 18 May 1980 southwest- flank lahars, Mount St. Helens, Washington|
|Series title||Journal of Sedimentary Petrology|
|Publisher||Society for Sedimentary Geology|
|Other Geospatial||Mount St. Helens|
|Google Analytic Metrics||Metrics page|