Clayey landslide initiation and acceleration strongly modulated by soil swelling

Geophysical Research Letters
By: , and 

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Abstract

Largely unknown mechanisms restrain motion of clay-rich, slow-moving landslides that are widespread worldwide and rarely accelerate catastrophically. We studied a clayey, slow-moving landslide typical of thousands in northern California, USA, to decipher hydrologic-mechanical interactions that modulate landslide dynamics. Similar to some other studies, observed pore-water pressures correlated poorly with landslide reactivation and speed. In situ and laboratory measurements strongly suggested that variable pressure along the landslide's lateral shear boundaries resulting from seasonal soil expansion and contraction modulated its reactivation and speed. Slope-stability modeling suggested that the landslide's observed behavior could be predicted by including transient swell pressure as a resistance term, whereas modeling considering only transient hydrologic conditions predicted movement 5–6 months prior to when it was observed. All clayey soils swell to some degree; hence, our findings suggest that swell pressure likely modulates motion of many landslides and should be considered to improve forecasts of clayey landslide initiation and mobility.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Clayey landslide initiation and acceleration strongly modulated by soil swelling
Series title Geophysical Research Letters
DOI 10.1002/2017GL076807
Volume 45
Issue 4
Year Published 2018
Language English
Publisher American Geophysical Union
Contributing office(s) Geologic Hazards Science Center
Description 9 p.
First page 1888
Last page 1896
Country United States
State California