Reid, Mark E.; LaHusen, Richard G.; Iverson, Richard M. 1997. Debris-flow initiation experiments using diverse hydrologic triggers. In: Chen, Cheng-lung, ed. Debris-flow hazards mitigation: mechanics, prediction, and assessment: Proceedings of first international conference; 1997 August 7-9; San Francisco, CA. New York, NY: American Society of Civil Engineers: 1-11.
Controlled debris-flow initiation experiments focused on three hydrologicconditions that can trigger slope failure: localized ground-water inflow; prolongedmoderate-intensity rainfall; and high-intensity rainfall. Detailed monitoring of slopehydrology and deformation provided exceptionally complete data on conditionspreceding and accompanying slope failure and debris-flow mobilization. Ground-water inflow and high-intensity sprinkling led to abrupt, complete failure whereasmoderate-intensity sprinkling led to retrogressive, block-by-block failure. Failureduring ground-water inflow and during moderate-intensity sprinkling occurred with arising water table and positive pore pressures. Failure during high-intensitysprinkling occurred without widespread positive pore pressures. In all three cases,pore pressures in most locations increased dramatically (within 2-3 seconds) duringfailure. In some places, pressures in unsaturated materials rapidly "flashed" fromzero to elevated positive values. Transiently elevated pore pressures and partiallyliquefied soil enhanced debris-flow mobilization.