HR: 11:15h
AN: C12A-04    [Abstracts]
TI: Triggering of Active-layer Detachment Landslides: Field Observation and Laboratory Modelling
AU: * Harris, C
EM: harrisc@cardiff.ac.uk
AF: School of Earth Ocean and Planetary Sciences, Cardiff University PO Box 914, Cardiff, CF103YE United Kingdom
AB: Permafrost degradation, resulting from Global Warming, is likely to increase the scale and frequency of thaw-related mass movements on slopes. Field studies of these processes present difficulties since prediction of where and when landslide events will occur is usually impossible, and long-term monitoring is necessary to collect substantial data sets. Shallow active-layer detachment slides in the polar desert environment of Ellesmere Island Canada, are described where triggering is apparently a response to unusually warm summer conditions, but landslide slope response is also apparently modulated by progressive reduction in shear strength over periods of one or two decades. An alternative approach to understanding such thaw-related slope failure mechanisms is through laboratory experiments in which model boundary conditions may be controlled. Since geotechnical centrifuge scaling laws show that time for both seepage force similarity and conductive heat transfer scale consistently, the centrifuge technique offers an ideal approach to the study of thaw consolidation processes in soils. Modelling experiments are described where the frozen model slopes were formed in silty clay. Models were thawed from the surface downwards at an acceleration of 20 gravities. Soil temperatures, pore water pressures during thaw and profiles of shear strain were recorded. Styles and mechanisms of failure are discussed in the context of the Ellesmere field study.
DE: 1823 Frozen ground
DE: 1824 Geomorphology (1625)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting