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Debris-flow deposition: Effects of pore-fluid pressure and friction concentrated at flow margins

January 1, 1999

Measurements of pore-fluid pressure and total bed-normal stress at the base of several ∼10 m3 experimental debris flows provide new insight into the process of debris-flow deposition. Pore-fluid pressures nearly sufficient to cause liquefaction were developed and maintained during flow mobilization and acceleration, persisted in debris-flow interiors during flow deceleration and deposition, and dissipated significantly only during postdepositional sediment consolidation. In contrast, leading edges of debris flows exhibited little or no positive pore-fluid pressure. Deposition therefore resulted from grain-contact friction and bed friction concentrated at flow margins. This finding contradicts models that invoke widespread decay of excess pore-fluid pressure, uniform viscoplastic yield strength, or pervasive grain-collision stresses to explain debris-flow deposition. Furthermore, the finding demonstrates that deposit thickness cannot be used to infer the strength of flowing debris.

Publication Year 1999
Title Debris-flow deposition: Effects of pore-fluid pressure and friction concentrated at flow margins
DOI 10.1130/0016-7606(1999)111<1424:DFDEOP>2.3.CO;2
Authors J. J. Major, R. M. Iverson
Publication Type Article
Publication Subtype Journal Article
Series Title Geological Society of America Bulletin
Index ID 70021283
Record Source USGS Publications Warehouse
USGS Organization Cascades Volcano Observatory