Showing papers by "Jacques Locat published in 2008"

A geomechanical approach for the genesis of sediment undulations on the Adriatic shelf

Abstract: [1] This study is among the first to examine the genesis of the seafloor and subsurface undulations on the Adriatic continental shelf by integrating stratigraphic information and in situ and laboratory geotechnical measurements. Interpretation of sediment behavior is based on a 32-m-long borehole crossing (1) a possible shear plane and (2) a silty clay layer at about 20 m below seafloor (mbsf) on which sediment undulations are rooted and could be interpreted as a potential weak layer succession. Our main results in terms of triggering mechanism for the observed undulations show that under an earthquake, liquefaction and/or failure of the silty-clay sediments (weak layer) leading to deformation of the upper more cohesive sediments is possible only when such a layer is buried by less than 5 m. For greater burial thicknesses, this silty clay becomes stable under the confining lithostatic pressure exerted by the overlying sediment. This work shows that the seafloor and subsurface undulations observed in the study area are most probably the result of an early deformation process of the seafloor followed by a depositional process.

Study of a lateral spread failure in an eastern Canada clay deposit in relation with progressive failure : the Saint Barnabé-Nord slide

Abstract: Study of a lateral spread failure in an eastern Canada clay deposit in relation with progressive failure : the Saint Barnabe-Nord slide

Terrestrial Lidar investigation of the 2004 rockslide along Petit Champlain Street, Québec City (Quebec, Canada)

Abstract: Au cours des 240 dernieres annees, 53 mouvements de versant se sont produits le long du promontoire de Quebec, causant la mort de 88 personnes principalement lors de chutes de blocs. En octobre 2004, un petit eboulement a atteint la route dans une zone proche de l'eboulement de 1889 qui a tue 35 personnes et blesse 30 autres. Une image 3D a ete creee par l'utilisation d'un scanner Lidar terrestre (SLT). Les sept familles de joints identifiees sont en accord avec les mesures effectuees dans de precedentes etudes. L'imagerie SLT a aussi permit d'estimer les volumes des instabilites passees et d'en analyser le mecanisme : un glissement rocheux qui affecte des blocs debites en parallelepipedes par d'autres familles de joints. De plus la zone etudiee montre qu'elle est favorable aux chutes de blocs.

Preliminary results of the U.S. Nuclear Regulatory Commission collaborative research program to assess tsunami hazard for nuclear power plants on the Atlantic and gulf coasts

Abstract: In response to the 2004 Indian Ocean Tsunami, the United States Nuclear Regulatory Commission (US NRC) initiated a long-term research program to improve understanding of tsunami hazard levels for nuclear facilities in the United States. For this effort, the US NRC organized a collaborative research program with the United States Geological Survey (USGS) and other key researchers for the purpose of assessing tsunami hazard on the Atlantic and Gulf Coasts of the United States. The initial phase of this work consisted principally of collection, interpretation, and analysis of available offshore data and information. Necessarily, the US NRC research program includes both seismicand landslide-based tsunamigenic sources in both the near and the far fields. The inclusion of tsunamigenic landslides, an important category of sources that impact tsunami hazard levels for the Atlantic and Gulf Coasts over the long time periods of interest to the US NRC is a key difference between this program and most other tsunami hazard assessment programs. Although only a few years old, this program is already producing results that both support current US NRC activities and look toward the long-term goal of probabilistic tsunami hazard assessment. This paper provides a summary of results from several areas of current research. An overview of the broader US NRC research program is provided in a companion paper in this conference.