Premium
Geotechnical in situ characterization of subaquatic slopes: The role of pore pressure transients versus frictional strength in landslide initiation
Author(s) -
Stegmann Sylvia,
Strasser Michael,
Anselmetti Flavio,
Kopf Achim
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl029122
Subject(s) - pore water pressure , geology , geotechnical engineering , submarine landslide , consolidation (business) , landslide , sedimentary rock , induced seismicity , slope stability , overpressure , shear (geology) , effective stress , slip (aerodynamics) , petrology , geomorphology , seismology , geochemistry , physics , accounting , business , thermodynamics
Mineralogical composition and pore fluid pressure are the crucial controls for mechanical stability of water‐saturated sediments. Their in situ measurements were undertaken in earthquake‐triggered slope deposits in Lake Lucerne (Switzerland) in addition to geophysical characterization and laboratory index properties, shear and consolidation experiments on core. Two lithological units were identified: A weak, lightly underconsolidated section of postglacial silty clays overlies overconsolidated fine‐grained glacial deposits with coarser components and excess fluid pressure (ca. 2.5× higher than in the hanging wall clay). In the event of an earthquake, hydrofracturing in the overconsolidated section facilitates an upward pore pressure pulse to the base of the softer, less stable unit. Here, excess pore pressure initiates sliding along a failure plane at the lithological boundary, causing the entire postglacial sedimentary section to slip downslope. We propose that many submarine landslides at active and passive continental margins may follow this mechanism of pore pressure‐induced failure.