Slope stability analyses based on sediment cores of the Ligurian Margin, Southern France


Autoria(s): Ai, Fei; Förster, Annika; Stegmann, Sylvia; Kopf, Achim J
Cobertura

MEDIAN LATITUDE: 43.528531 * MEDIAN LONGITUDE: 7.386983 * SOUTH-BOUND LATITUDE: 43.510833 * WEST-BOUND LONGITUDE: 7.351833 * NORTH-BOUND LATITUDE: 43.541167 * EAST-BOUND LONGITUDE: 7.436667 * DATE/TIME START: 2007-08-03T08:09:00 * DATE/TIME END: 2007-08-07T07:57:00

Data(s)

06/11/2014

Resumo

Submarine slope failures of various types and sizes are common along the tectonic and seismically active Ligurian margin, northwestern Mediterranean Sea, primarily because of seismicity up to ~M6, rapid sediment deposition in the Var fluvial system, and steepness of the continental slope (average 11°). We present geophysical, sedimentological and geotechnical results of two distinct slides in water depth >1,500 m: one located on the flank of the Upper Var Valley called Western Slide (WS), another located at the base of continental slope called Eastern Slide (ES). WS is a superficial slide characterized by a slope angle of ~4.6° and shallow scar (~30 m) whereas ES is a deep-seated slide with a lower slope angle (~3°) and deep scar (~100 m). Both areas mainly comprise clayey silt with intermediate plasticity, low water content (30-75 %) and underconsolidation to strong overconsolidation. Upslope undeformed sediments have low undrained shear strength (0-20 kPa) increasing gradually with depth, whereas an abrupt increase in strength up to 200 kPa occurs at a depth of ~3.6 m in the headwall of WS and ~1.0 m in the headwall of ES. These boundaries are interpreted as earlier failure planes that have been covered by hemipelagite or talus from upslope after landslide emplacement. Infinite slope stability analyses indicate both sites are stable under static conditions; however, slope failure may occur in undrained earthquake condition. Peak earthquake acceleration from 0.09 g on WS and 0.12 g on ES, i.e. M5-5.3 earthquakes on the spot, would be required to induce slope instability. Different failure styles include rapid sedimentation on steep canyon flanks with undercutting causing superficial slides in the west and an earthquake on the adjacent Marcel fault to trigger a deep-seated slide in the east.

Formato

application/zip, 20 datasets

Identificador

https://doi.pangaea.de/10.1594/PANGAEA.837975

doi:10.1594/PANGAEA.837975

Idioma(s)

en

Publicador

PANGAEA

Direitos

CC-BY: Creative Commons Attribution 3.0 Unported

Access constraints: unrestricted

Fonte

Supplement to: Ai, Fei; Förster, Annika; Stegmann, Sylvia; Kopf, Achim J (2014): Geotechnical Characteristics and Slope Stability Analysis on the Deeper Slope of the Ligurian Margin, Southern France. In: Kyoji Sassa, Paolo Canuti, Yueping Yin (eds.), Landslide Science for a Safer Geoenvironment, Volume 3: Targeted Landslides. Springer International Publishing AG, Switzerland, 549-555, doi:10.1007/978-3-319-04996-0_84

Palavras-Chave #Calculated; Center for Marine Environmental Sciences; cu; CU; Density; Depth; DEPTH, sediment/rock; Direct shear apparatus (GIESA, Germany); Effective stress; Event; Fall cone penetration test; Magnetic susceptibility; MAGS; MARUM; Multi-Sensor Core Logger; Normal stress; Oedometer; p; Poros frac; Porosity, fractional; Ratio; Shear strength, undrained; Shear stress; Sigma; SigmaN; SigmaV ef; Tau; undained shear stress/vertical effective stress, cu/p; undraine shear stress with set value of cu/p=0.2; undraine shear stress with set value of cu/p=0.4; Vane shear apparatus; Vertical effective stress; Void ratio; Water content of wet mass; Water wm
Tipo

Dataset