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Corinth Gulf Landslides 3HAZ Program WP5 T. Lebourg, S. El Bedoui, A. Deschamps and Y. Guglielmi 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 2 Participant of CNRS/Geoazur to the landslide project : Leader WP5 : Th. Lebourg (mdc) Tacheometry, topography S. El Bedoui (PhD student) S Lemeunier (engineer) Electrical tomography Th. Lebourg (mdc) Seismological recording on the landslide A. Deschamps (DR) InstrumentationField studies Geologie, geomorphology S. El Bedoui (PhD student) Th. Lebourg (mdc) Hydrogeology Y. Guglielmi (mdc) Cyclique and standard triaxial tests Th. Lebourg (mdc) M. Hernandez (PhD student) FLAC3D-TOUGH simulations Y. Guglielmi (mdc) Modelling In Process WP5a,c WP5c WP5d WP5b WP5a,c WP5f Slide 3 Landslides in Corinth Gulf Greece Gulf of Corinth Sergoula and Marathias landslides Panagopoula landslides High relation with tectonics faults 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 4 WP5: Documenting the Panagopoula landslide One photo (1971) and one paper in engineering geology and environment Impossibility to have available information on the previous study () Legend: Red : target in active area Yellow : target in intermediary area Green : target in inactive area Autoroute Patras Limit of the active part Limit of the landslide (paleolandslide) C1 C2 C5 C7 C4 C6 C8 C10 C3 C9 South North Lewis Project ??? 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 5 WP5.c: Panagopoula data analysis Sliding surface Mechanical behaviour of the material on the sliding surface Standard Triaxial tests Cohesion, angle of friction, elasticity modulus 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 6 Landslides map Topometric network: targets and stations WP5.b: Instrumentation of the Panagopoula landslide 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 7 Topometric survey: 6 months displacement Tectonic signal ? 16mm 5mm 13mm 12mm 18mm 3mm 12mm 13mm 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 8 Two components: 1. Long term slide (10-16mm/y) 2. Short term acceleration 2 different landslides A large scale movement, controlled by structural discontinuities A superficial creep mobilizing the more weathered formations Results from the one year survey Slide 9 Field study Cross section 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 10 Slide 11 Landslides map Landslides activity in deep ??? Electrical tomography 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 12 The geo-electrical tomography: Geological contact Tectonic Faults Failure surface In deep 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 13 Actual Landslide body Drained Faults ? Next Landslide body Weathered rock mass 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 14 Results from the correlation between field and geophysical investigations 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 15 Tectonic and gravitational correlations a clear link between E-W tectonic faults and gravitational scarps, movements measured is linking with superficial creep of soils,.. Mud and debris flow movements between topometric stations could be explain by extensional tectonic activity (Psathopyrgos normal fault) Instrumented area to study the tectonic control of landslide activity Conclusion on Panagopoula Landslide 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 16 Accomodation of deep processes at the surface by landsliding?? (P. Briolle) Large scale movements (GPS) Topometric survey Conglomrats Secteur dtude de Panagopoula (Flott) 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 17 North coast of Corinth Gulf Sergoula landslide No human activity located in the Marathias fault zone (E-W structures), near Trisonia Island (instrumented: GPS, tiltmeters, seismological survey), Collaboration with Koukouvela I & Gallousi X (U. Patras). 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 18 North South E-W normal fault Trisonia Island Electrical tomography Sergoula area On the foot of the landslide body and on the debris fan 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 19 Slide 20 Slide 21 Normal faulting is closed by river and gravitational deposits And tectonic activity controls Sergoulas sliding Landslides events 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 22 Slide 23 Datation landslides events with Dendrochronology Calcite and C14 On a fault scarp We hope to realise an instrumentation on and around the landslide with : Permanent geophysical prospecting, tiltmeters, seismological survey. 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 24 A1A1 A2A2 A3A3 A4A4 Rainfall event AnAn A n+1 - Research signal resistivity/fluid by temporal survey Slide 25 Slide 26 Conclusion the Panagopoula landsliding is a very little and slow landslide, field studies and geophysical survey are well correlated to produce a geological model, electrical tomography gives quantitative and qualitative data about structural boundaries, a clear link appears between tectonic and gravitational features. 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 27 Perspectives North and south coast of Corinth gulf are an appropriate area to study the tectonic control of landslides processes Thank you for your attention 3HAZ MEETING, 2-3 DECEMBER 2006, ATHENS Slide 28 NorthSouth Slide 29 WP5.d: Modelling of slip instability 2D Numerical analysis of Panagopoula type landslide Goal : Examining failure mechanisms and their relashionship To South Corinthe gulf coastal slopes characteristics FLAC3D-TOUGH simulations : - Static (seepage effects) - Dynamic (earthquake effects) (Martino et al., 2005) Slide 30 Topometric survey: results after 6 months gravitational movement, slow movements, principal movements are located in the paleo-landslide body, general increase of displacement between april and june. Pluviometry: january to june 2006